Nonmigratory internal plasticization of poly(vinyl chloride) via pendant triazoles bearing alkyl or polyether esters

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ORIGINAL ARTICLE

Nonmigratory Internal Plasticization of Poly(Vinyl Chloride) via Pendant

Triazoles Bearing Alkyl or Polyether Esters

1

2

1

Chad M. Higa , Andy T. Tek, Rudy J. Wojtecki , Rebecca Braslau

1

Department of Chemistry and Biochemistry, University of California, Santa Cruz, 1156 High Street, Santa Cruz, California 95064, US

IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, US

2

Correspondence to: R. Braslau (E-mail: rbraslau@ucsc.edu)

Received 11 July 2018; Accepted 24 July 2018

DOI: 10.1002/pola.29205

ABSTRACT

to generate additional space between the triazole-phthalate mimic

and the polymer backbone. Miscibility of these triazole-plasticizers

in PVC is important: variation of the ester moieties on the triazole

possessing alkyl and/or poly(ethylene oxide) chains produced a

Branched and linear nonmigratory internal plasticizers attached to

PVC by a pendant triazole linkage were synthesized and investi-

gated. Copper-free azide-alkyne thermal cycloaddition was

employed to covalently bind triazole-based phthalate mimics to

PVC. To systematically investigate the effect of plasticizer struc-

ture on glass transition temperature, several architectural motifs

were explored. Free volume theory was considered when design-

ing many of these internal plasticizers: hexyl-tethers were utilized

wide range of glass transition temperatures (T

g

): from anti-

ꢀ

plasticizing 96 C, to highly efﬁcient plasticized materials exhibit-

ꢀ

ing T

g

J. Polym. Sci., Part A: Polym. Chem. 2018

9–15

INTRODUCTION

organs,

and act as potent endocrine disrupting chemicals

that cause deleterious pre- and postnatal developmental effects,

Poly(vinyl chloride) (PVC) is one of the most utilized thermo-

1

6–19

notably in males.

Bans of DEHP by the European

plastics, with worldwide demand reaching 41.5 million tons in

2

0–23

24

Union

spurred the development of less-toxic PVC plasticizer

and the United States in children’s articles has

1

2

016. However, PVC by itself is brittle and not readily pro-

cessable. This material reached the success of its worldwide

demand because of phthalates, a cost-effective additive (emol-

lient) that imparts ﬂexibility and resistivity toward weather-

ing, temperature extremes, and electrical conductivity. The use

of phthalates as plastic emollients is widespread, representing

4

,25–31

alternatives.

A strategy known as tethering involves cova-

lently bonding a plasticizer to PVC. This prevents leaching and

migration, leading to internally plasticized materials.

Recent efforts have explored internal plasticizers via thioether

78% of global plasticizer demand in 2012, with applications

3

2

tethering: Michel described 2-ethylhexyl esters of thiosalicy-

late and thioglycolate as plasticizing agents via nucleophilic

ranging from industrial to consumer products such as coatings

for electrical materials, building supplies, car interiors, ﬂoor-

3

2

substitution of the chlorine atoms in PVC. Reinecke utilized

-ethylhexyl-mercapto-phthalates as internal plasticizers for

ing, sealants, cosmetics, and personal care products.

2

PVC. Subsequently, aliphatic nonphthalate analogs containing

ester/amide, carbonate/carbamate, and sulfonyl-ester/amide

groups to functionalize the thiophenols with alkyl chains were

The pervasive utilization of low molecular weight blended

phthalates as emollients inevitably leads to leaching and con-

tamination of the environment. Human exposure is widespread

and unavoidable. Routes of exposure come in many forms:

ingestion, inhalation, dermal absorption, and intravenous leach-

3

4

developed. Recently, a one-pot approach using thiolated tri-

3

4–36

chlorotriazines (TCTA) gave self-plasticized PVC.

These

3

ing. Ingestion has been shown to be the primary source of

strategies are summarized graphically in Supporting Informa-

tion, Figure S1(a).

phthalate exposure in the general population through dietary

3

3–8

intake of contaminated food. Medical devices also introduce

phthalate, most notably di-(2-ethylhexyl) phthalate, DEHP 1a

Natural product-derived inexpensive internal plasticizers have

3

7–39

37

(

Fig. 1) into hospital patients via containers holding blood,

also been developed.

Zhou functionalized PVC with

nutritional formulas, and respiratory gases. Phthalates and their

metabolites have displayed negative effects on various

aminated tung oil, exploiting the nucleophilic nature of an

amine generated by trans-amidation to displace the chlorides

Additional supporting information may be found in the online version of this article.

2018 Wiley Periodicals, Inc.

©

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FIGURE

1 Di-(2-ethylhexyl) phthalate (DEHP) 1a and di-

(2-ethylhexyl) triazole phthalate mimic 1b.

3

8

on PVC. This approach was also applied to waste cooking oil

and cardanol [Supporting Information, Fig. S1(b)].

3

9

The copper-mediated azide-alkyne cycloaddition (CuAAC) has

become a popular strategy to covalently attach plasticizing

4

0–44

moieties.

All these polymers suffer from residual copper

4

0–44

40

contamination in the plasticized PVC. Both Yang and

Zhou utilized CuAAC to functionalize PVC-azide with carda-

nol and commercially available triethyl citrate. Kwak

FIGURE 2 “Type” designation of triazole-plasticizers.

4

3

4

0

43

42

ꢀ

240 mL of THF at 50 C. This solution was allowed to cool to

also used this method to graft a hexyl ester-terminated hyper-

branched polyglycerol plasticizer onto PVC-azide. Tasdelen

and Demirici grafted poly(ε-caprolactone) in a similar fash-

room temperature and precipitated in 800 mL of methanol.

The mother liquor was ﬁltered and the dissolution–

precipitation process was repeated two more times. Tetrahy-

drofuran was supplied by Fisher Scientiﬁc and was dried over

sodium and benzophenone, under argon when anhydrous con-

ditions were required. Silica gel (Grade 60, 230–400 mesh,

40–63 μm particle size) was supplied by Sorbent Technologies

and was utilized for column chromatography. Hexanes (4.2%

methylpentanes), ethyl acetate, dichloromethane (stabilized

HPLC grade, submicron ﬁltered), methanol, ethanol (absolute,

200 proof, molecular biology grade), acetonitrile (Optima™,

LC/MS grade), tetrahydrofuran (HPLC grade, submicron ﬁl-

tered, uninhibited), toluene (HPLC grade), acetone (HPLC

grade), dimethylformamide (sequencing grade), pentanes

(HPLC grade, submicron ﬁltered), diethyl ether (BHT stabi-

lized), sodium chloride (crystalline), sodium bromide (granu-

lar), sodium bicarbonate (granular powder), potassium

hydroxide (pellets), magnesium sulfate (anhydrous, powder),

sodium sulfate (anhydrous, granular), concentrated hydro-

chloric acid (36.9%), concentrated sulfuric acid, bromine, zinc

powder (99.2%), n-butanol (HPLC grade), and Celite™ 545 -

ﬁltering aid (non-acid-washed) were supplied by Fisher

Scientiﬁc and used as delivered without additional puri-

ﬁcation. Dimethylsulfoxide (≥99.9%), carbon tetrachloride

(anhydrous, ≥99.5%), 3-pentanone (≥99%), phosphorous pen-

tachloride (≥98.0%, purum p.a.), pyridine (anhydrous, 99.8%),

iodine (≥99.99% trace metals basis), tri(ethylene glycol)

monomethyl ether (95%), poly(ethylene glycol) monomethyl

ether 350, and poly(ethylene glycol) monomethyl ether

550 were supplied by Sigma-Aldrich and used as delivered

without additional puriﬁcation. 6-Chlorohexanol (>96%),

poly(ethylene glycol) monomethyl ether 1000, poly(ethylene

glycol) monomethyl ether 2000, acetylenedicarboxylate mono-

potassium salt (>95%), tetrabutylammonium hydrogensulfate

4

1

ion [Supporting Information, Fig. S1(c)].

In a departure from the commonplace copper-catalyzed cycliza-

4

4,45

tions, Braslau and Earla

employed mild copper-free thermal

azide-alkyne cycloadditions to attach acetylenedicarboxylate

esters bearing alkyl groups, with the intended purpose of creating

triazole-based phthalate analogues along the backbone to furnish

internally plasticized PVC [Supporting Information, Fig. S1(c)].

In this current study, nonmigratory plasticizers attached to

pendant triazole linkages were investigated. Copper-free ther-

mal azide-alkyne cycloadditions were employed to functionalize

PVC with an array of triazole-based phthalate mimics 1b.

Design rules for internal plasticizers on PVC have not yet been

ﬁrmly established: this study aims to systematically investigate

the effect of plasticizer structure on glass transition tempera-

ture. Factors such as branching, plasticizing group composition,

and miscibility were explored. The concept of free volume the-

4

6

ory led to introduction of a ﬂexible hexyl tether to generate

increased volume between the internal plasticizer and the poly-

mer backbone. Three architectural types of triazole-plasticizers

were developed (Fig. 2): “Type 0” has no tether, “Type 1” con-

tains a single tether, and “Type 2” possesses two tethers. The

“D” or “M” designation after Type 0 derivatives represents di-

substituted or mono-substituted ester triazoles. The solubility

of the triazole anchored plasticizers is important for both alkyl

and poly(ethylene oxide) (PEO) derivatives. A range of glass

g

transition temperatures (T ) were obtained, from an anti-

ꢀ

plasticizing 96 C, to highly efﬁcient internally plasticized PVC

ꢀ

with a T

g

of −42 C.

(

3

>98%), vinyl chloroacetate (>99%, MEHQ stabilizer), and

-pentanone (>98.0%) were supplied by Tokyo Chemical

EXPERIMENTAL

Materials

Industries (TCI) and used as delivered without additional

puriﬁcation. Sodium azide (99%, extra pure), acetylenedicar-

boxylic acid (98%), propiolic acid (98%), p-toluenesulfonic

PVC (M : 43,000 g/mol, PDI: 1.95) was supplied by Sigma-

w

Aldrich and puriﬁed by dissolution of 20.00 g of PVC in

2

JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2018

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ORIGINAL ARTICLE

acid monohydrate (99%, extra pure), pyridine (99%), and

potassium bromide were supplied by Acros Organics and used

as delivered without additional puriﬁcation. Dimethyl acetyle-

nedicarboxylate (98%), 2-ethyl-1-hexanol (99%), propiolic

acid (>98%), and n-hexane (95% HPLC distilled in glass) were

supplied by Alfa Aesar and used as delivered without addi-

tional puriﬁcation. Dioctyl phthalate (CAS: 117–81-7) and

sodium bisulﬁte (granular, F.C.C.) were supplied by Spectrum

and used as delivered without additional puriﬁcation.

Chloroform-d (D, 99.8%) and benzene-d₆(D, 99.5%) were

supplied by Cambridge Isotope Laboratories and used as

delivered without additional puriﬁcation.

Warning on Organic Azides

Organic azides can be dangerous in nature: low molecular

weight organic azides have propensity to violently

decompose. A formula to determine if an organic azide is

a

4

7

safe to handle has been created:

(NCarbon + NOxygen)/

N

Azide Nitrogen ≥ 3, where N = number of atoms. While

6-azidohexanol and PVC-azide did not show signs of violent

decomposition, it should be noted that extreme caution

should be taken at all times when synthesizing or handling

organic azides.

Syntheses of Triazole Plasticized PVC

Representative experimentals have been selected for each

triazole (TRZ) plasticizer type due to the large total amount of

molecules and polymers synthesized for the study. Experi-

mentals for all samples are given in the Supporting

Information.

Measurements

Nuclear magnetic resonance (NMR) spectra were recorded

with a Bruker Avance III HD 4 channel 500 MHz Oxford Mag-

net NMR Spectrometer with Automation, Varian Unity Plus

5

00 MHz Oxford Magnet NMR Spectrometer, or Bruker

1

Avance III HD 800 MHz NMR Spectrometer. H-NMR spectra

taken in deuterated chloroform (CDCl ) used the CHCl signal

δ 7.26 ppm) as an internal standard, and the CDCl triplet (δ

7.27 ppm) for C-NMR. H-NMR spectra taken in benzene-

PVC-Azide Synthesis

Preparation of 15% PVC-Azide

4

4,45,48

3

(

7

3

Puriﬁed poly(vinyl chloride) (2.000 g, 21.68 mmol) was added

to a 100 mL round-bottom ﬂask and dissolved in 20 mL of

1

3

1

ꢀ

d utilized the C H (δ 7.15 ppm) as an internal standard, and

dimethylformamide at 62 C. Sodium azide (2.000 g,

6

6 6

1

3

the C D triplet (δ 127.68 ppm) for C-NMR. Fourier trans-

30.76 mmol) was subsequently added and stirred for 2 h. The

reaction was immediately ﬁltered through a large Buchner

funnel with a Whatman™ grade 1 qualitative ﬁlter paper into

a vacuum ﬂask. The reaction solution was slowly precipitated

into 200 mL of MeOH then ﬁltered through a Buchner funnel

and Whatman™ grade 1 qualitative ﬁlter paper into a vacuum

ﬂask. The polymer was dried for 15 min under house vacuum

and dissolved in 20 mL of THF. The dissolved polymer was

slowly precipitated into 100 mL of MeOH then ﬁltered

through a Buchner funnel and Whatman™ grade 1 qualitative

ﬁlter paper into a vacuum ﬂask. This process was repeated

once more with MeOH. The dissolved PVC was dissolved into

10 mL of THF and slowly precipitated in 100 mL of a 3:1 mix-

6

form infrared spectroscopy (FTIR) was recorded with a

Perkin-Elmer Spectrum One Spectrometer, with sodium chlo-

ride (NaCl) plates. Liquids were measured neat. Polymers

were measured as dried thin ﬁlms. Solid molecules were com-

bined, ground, and pressed into potassium bromide (KBr)

plates using a Carver press. High-resolution mass spectros-

copy (HRMS) was recorded with a Thermo Scientiﬁc LTQ-

Orbitrap Velos Pro MS. HRMS was taken with samples dis-

3

solved in acetonitrile (CH CN). Elemental analysis was per-

formed by MHW Laboratories. Modulated differential

scanning calorimetry (MDSC) was performed on each polymer

using a TA Instruments DSC Q2000 with a heat-cool-heat pro-

tocol. The general scanning ranges of MDSC analyses ranged

ture of MeOH:H O, ﬁltered, and dried for 15 min under house

2

ꢀ

−1

from −90 to 200 C, with a heating rate of 10 C min . Deriv-

ative thermogravimetry (DTG) and thermal gravimetric ana-

lyses (TGA) were performed with a TA Instruments TGA

Q500. TGA was performed within a scanning range of 30 to

vacuum then dissolved in 20 mL of THF. The ﬁnal precipita-

tion was performed in MeOH. The isolated polymer was dried

under house vacuum for 5 days via Buchner funnel to give

1.206 g of the title compound as a ﬂocculent white solid. H

NMR (500 MHz, CDCl , δ, ppm): 4.68–4.26 (br m, Cl-C-H), 4.20

1

ꢀ

−1

5

00 C, with a heating rate of 10 C min in air or nitrogen.

3

(

br s, N-C-H), 4.09 (br s, N-C-H), 2.51–2.02 (br m, Cl-C-CH -C-

2

1

3

Plasticizer Migration Study

Cl), 1.98–1.77 (br m, Cl-C-CH -C-N and N -C-CH -C-N ).

C

2

3

2

3

The degree of plasticizer migration was determined by a pro-

cess derived from an ASTM International standard test

method (ASTM-D5227). Samples were extracted as square

ﬁlms (~15 × 15 mm ), dried by high vacuum overnight and

weighed. A Berzelius beaker (150 mL) with a stir bar

NMR (125 MHz, CDCl

56.1–55.7 (CH hetero), 55.1–54.9 (CH iso), 47.3–44.8 (family

3

, δ, ppm): 57.0–56.9 (CH syndio),

−

1

of CH

2 2

peaks), 44.0–42.8 (N-C-CH ). IR (NaCl, neat, cm ):

2

2975 (m, alkane CH), 2911 (m, alkane CH), 2114 (s, N

3

), 1435

ꢀ

(m, methylene stretch CH

), 615 (w, C–Cl). DSC (T

2

): 78 C.

g

(

25 mm × 8 mm diameter) was utilized as the extraction

ꢀ

apparatus. 50 mL of n-hexane was preheated at 50 C for

Alkyl Type 0D Syntheses

Preparation of 1,4-bis(2-Ethylhexyl) but-2-Ynedioate

(2c)

But-2-ynedioic acid (3.422 g, 30.00 mmol) was added to

a 100 mL round-bottom ﬂask. 2-Ethylhexan-1-ol (8.595 g,

66.00 mmol) was then added along with 4-methylbenzenesul-

fonic acid (0.342 g, 1.800 mmol) and 42 mL of dry toluene.

Using a Dean-Stark apparatus, the reaction was heated and

1

5 min prior to placing the polymer in the beaker. A stir rate

4

4,45

of 100 revolutions per minute was used for all extractions.

Each sample was extracted for 2 h at 50 C. After the extrac-

tion, the solvent was decanted. The polymer was placed in a

ꢀ

20 mL scintillation vial and dried under high vacuum at room

temperature overnight. The mass of each sample postextrac-

tion was determined.

JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2018

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stirred at reﬂux for 1 h. The organic layer was concentrated in

vacuo to give a crude brown oil. Puriﬁcation via ﬂash chroma-

tography using 95:5 hexanes:ethyl acetate afforded 9.211 g

yield) of the title compound as a colorless oil. R

f

: 0.53 (SiO

2

,

1

CH Cl :MeOH, 95:5). H NMR (500 MHz, CDCl , δ, ppm):

2

3

4.39–4.31 (m, 4H), 3.74–3.70 (m, 4H), 3.65–3.60 (m, 12H),

1

3

(

27.21 mmol, 73.69% yield) of a colorless oil, as a mixture of

3.56–3.49 (m, 4H), 3.37–3.33 (m, 6H). C NMR (125 MHz,

1

ꢀ

diastereomers. R

NMR (500 MHz, CDCl

m, 2H), 1.42–1.36 (m, 4H), 1.35–1.25 (m, 12H), 0.91 (t, 12H).

f

: 0.80 (SiO

2

, hexanes:ethyl acetate, 95:5). H

CDCl

3

, δ, ppm): 151.6 (C O), 74.7 (alkyne 4 ), 71.9 (CH

2

),

3

, δ, ppm): 4.19–4.13 (m, 4H), 1.66–1.61

70.7 (CH

2

), 70.6 (CH

2

), 68.4 (CH

2

), 65.8 (CH

2

), 58.9 (CH

3

). IR

−

1

(

(NaCl, neat, cm ): 2879 (s, alkane CH), 1725 (s, ester C O),

1

3

ꢀ

C NMR (125 MHz, CDCl , δ, ppm): 152.0 (C O), 74.7 (4 ),

1259 (s, ester stretch C–O), 1110 (s, ether stretch C–O). HRMS

3

6

2

9.2 (O-CH ), 38.6 (CH), 30.1 (CH ), 28.8 (CH ), 23.5 (CH ),

(m/z):

407.1895 [M + H] .

calcd

for

C H O

18 30 10

407.1912;

found,

2

−

1

+

2.9 (CH ), 14.0 (CH ), 10.8 (CH ). IR (NaCl, neat, cm ): 2962

2

3

(

s, alkane CH), 2932 (s, alkane CH), 2875 (s, alkane CH), 2862

s, alkane CH), 1725 (s, ester C O), 1464 (s, methylene bend-

Preparation of 15% PVC-TRZ-DiPEO164Me (3d)

ing CH

2

), 1255 (s, ester stretch C–O). HRMS (m/z): calcd for

Poly(vinyl chloride) 15% azide (1.000 g, 16.00 mmol) was

+

C

20

H

35

O

4

339.2529; found, 339.2525 [M + H] .

added to a 100 mL round-bottom ﬂask and dissolved in

ꢀ

2

0 mL of 3-pentanone at 90 C. 1,4-Bis({2-[2-(2-methox-

Preparation of 15% PVC-TRZ-DiEH (3c)

Poly(vinyl chloride) 15% azide (1.000 g, 16.00 mmol) was

yethoxy)ethoxy]ethyl})but-2-ynedioate (2.424 g, 6.000 mmol)

was added to the PVC solution and stirred for 72 h. The reac-

tion was concentrated to approximately half its volume in

vacuo, then precipitated in 80 mL of MeOH, three times each.

The isolated polymer was dried under house vacuum for

added to a 100 mL round-bottom ﬂask and dissolved in

ꢀ

2

0 mL of 3-pentanone at 90 C. 1,4-Bis(2ethylhexyl) but-

-ynedioate (2.437 g, 7.200 mmol) was added to the PVC solu-

ꢀ

tion and stirred for 24 h. The reaction was precipitated in

0 mL of MeOH, three times each. The isolated polymer was

dried under house vacuum for 2 days to yield 0.930 g of a

1 day, then in a vacuum oven at 40 C for 3 days to yield

1

8

1.330 g of a white solid. H NMR (500 MHz, CDCl , δ, ppm):

3

5.66–5.44 (br m, C-CH-triazole), 4.63–4.54 (br s, Cl-C-H),

1

ﬂocculent white solid. H NMR (500 MHz, CDCl

3

, δ, ppm):

.65–5.40 (br m, C-CH-triazole), 4.67–4.40 (br m, Cl-C-H),

.39–4.10 (br m, Cl-C-H and O-CH -C), 2.92–2.81 (br t, Cl-C-

4.54–4.39 (br s, Cl-C-H and triazole-O-CH

Cl-C-H), 3.87–3.79 (br m, triazole-O-C-CH -O), 3.76–3.68 (br m,

triazole-O-C-C-O-CH -CH -O-CH -C), 3.58–3.53 (br m, C-CH -O-

CH ), 3.40–3.36 (br s, O-CH ), 2.92–2.81 (br m, Cl-C-CH -C-tria-

2

), 4.36–4.24 (br m,

5

4

2

CH -C-triazole and triazole-C-CH -C-triazole), 2.81–2.67 (br m,

2

3

2

Cl-C-CH -C-triazole and triazole-C-CH -C-triazole), 2.50–1.85

zole and triazole-C-CH -C-triazole), 2.80–2.66 (br m, Cl-C-CH -

2 2

2

(

0

(

br m, Cl-C-CH -C-Cl), 1.80–1.60 (br m, O-C-CH-C), 1.52–1.36

C-triazole and triazole-C-CH -C-triazole), 2.50–1.95 (br m, Cl-C-

2

1

3

br m, O-C-C-CH

2

), 1.35–1.26 (br s, O-C-C-C-CH

2

-CH

, δ, ppm): 160.1

C O), 158.7 (C O), 139.5 (4 ), 132.6 (4 ), 70.0 (O-CH ), 69.9

O-CH ), 68.5 (O-CH ), 57.0–56.9 (CH syndio), 56.4 (CH-

2

),

CH

158.3 (C O), 138.6 (4 ), 131.7 (4 ), 71.9 (CH

70.62 (CH ), 70.57 (CH ), 68.7 (CH ), 68.4 (CH

64.9 (CH ), 59.0 (CH

(CH hetero), 55.2–54.9 (CH iso), 47.3–44.8 (family of CH

2 3

-C-Cl). C NMR (125 MHz, CDCl , δ, ppm): 159.7 (C O),

1

3

ꢀ

.97–0.85 (m, CH

3

). C NMR (125 MHz, CDCl

3

2

), 70.67 (CH

), 66.2 (CH

2

),

ꢀ

2

3

), 57.0–56.9 (CH syndio), 56.1–55.9

triazole syndio), 56.1–55.9 (CH hetero), 55.2–54.9 (CH iso),

2

−

1

4

3

2

7.3–44.8 (family of CH₂PVC peaks), 38.7 (CH), 38.6 (CH),

peaks). IR (NaCl, thin ﬁlm, cm ): 2879 (s, alkane CH), 1734

0.2 (CH ), 30.1 (CH ), 28.9 (CH ), 28.8 (CH2), 23.6 (CH ),

(s, ester C O), 1549 (s, triazole C C), 1452 (s, methylene

stretch CH ), 1259 (s, ester stretch C–O), 1200 (s, ester

2

3.5 (CH

2

), 23.0 (CH

2

), 14.1 (CH

3

), 10.9 (CH

3

). IR (NaCl, thin

−

1

ﬁlm, cm ): 2961 (s, alkane CH), 2932 (s, alkane CH), 2874 (s,

alkane CH), 2862 (s, alkane CH), 1721 (s, ester C O), 1555

stretch C–O), 1107 (s, ether stretch C–O), 611 (w, C–Cl). DSC

ꢀ

(T

g

): 42 C.

(

w, triazole C C), 1463 (m, methylene stretch CH ), 1255 (s,

2

ꢀ

ester stretch C–O), 616 (w, C–Cl). DSC (T ): 57 C.

Alkyl Type 1 Syntheses

Preparation of 6-Azidohexan-1-ol (4)

g

4

9

PEO Type 0D Syntheses

6-chlorohexan-1-ol (1.500 g, 10.98 mmol) was added to a

Preparation of 1,4-bis({2-[2-(2-Methoxyethoxy)Ethoxy]

Ethyl})but-2-Ynedioate (2d)

But-2-ynedioic acid (1.000 g, 8.767 mmol) was added to a

100 mL round-bottom ﬂask with 20 mL of dimethyl sulfoxide.

NaN (1.071 g, 16.47 mmol) was carefully added to the reac-

3

ꢀ

tion ﬂask and stirred for 24 h at 50 C. After 24 h, 40 mL of

5

0 mL round-bottom ﬂask. Triethylene glycol monomethyl

water was poured into the round-bottom ﬂask. The reaction

was extracted ﬁve times using 30 mL each of ethyl acetate.

The organic layers were washed with brine four times using

20 mL each, and then dried with Na SO . The volatiles were

ether (3.167 g, 19.29 mmol) was then added along with

4

1

-methylbenzenesulfonic acid (0.167 g, 0.876 mmol) and

3 mL of dry toluene. Using a Dean-Stark apparatus, the reac-

2

4

tion was heated and stirred at reﬂux for 5 h. The reaction was

evaporated in vacuo affording 1.572 g (10.98 mmol, quantita-

transferred to a 150 mL separatory funnel and diluted with

tive yield) of the title compound as a colorless oil. R : 0.46

f

1

40 mL of toluene and washed with 20 mL of saturated

(SiO

2

, hexanes:ethyl acetate, 3:2). H NMR (500 MHz, CDCl

3

, δ,

NaHCO three times each. The aqueous layer was extracted

with 60 mL of ethyl acetate, three times each. The combined

3

ppm): 3.60 (t, J = 6.6 Hz, 2H), 3.24 (t, J = 6.9 Hz, 2H),

1

3

1.61–1.52 (m, 4H), 1.41–1.31 (m, 4H). C NMR (125 MHz,

CDCl , δ, ppm): 62.7 (CH -OH), 51.4 (CH -N ), 32.5 (CH ), 28.8

organic layers were dried with MgSO , ﬁltered, and concen-

4

3

2

3

2

−

1

trated in vacuo. Puriﬁcation via ﬂash chromatography using

(CH ), 26.5 (CH ), 25.3 (CH ). IR (NaCl, neat, cm ): 3351 (s,

2 2 2

9

5:5 CH Cl :MeOH afforded 2.673 g (6.576 mmol, 75.02%

OH), 2937 (s, alkane CH), 2862 (s, alkane CH), 2097 (s, N₃),

2

4

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ORIGINAL ARTICLE

ꢀ

1

457 (m, methylene bending CH

2

), 1056 (s, 1 alcohol stretch

Preparation of 15% PVC-TRZ-Hexyl-TRZ-DiEH (7c)

C–O). HRMS (m/z): calcd for C H N O 144.1131; found,

Poly(vinyl chloride) 15% azide (1.000 g, 16.00 mmol) was

6

13 3

+

144.9812 [M + H] .

added to a 100 mL round-bottom ﬂask and dissolved in

ꢀ

2

1

0 mL of 3-pentanone at 90 C. 4,5-Bis(2-ethylhexyl)-

-[6-(prop-2-ynoyloxy)hexyl]-1H-1,2,3-triazole-4,5-dicarboxylate

Preparation of 4,5-bis(2-Ethylhexyl) 1-(6-Hydroxyhexyl)-

(3.843 g, 7.200 mmol) was added to the PVC solution and stir-

1

6

1

H-1,2,3-Triazole-4,5-Dicarboxylate (5c)

-Azidohexan-1-ol (1.570 g, 10.98 mmol) was added to a

00 mL round-bottom ﬂask with 35 mL of CHCl . 1,4-Bis

red for 24 h. The reaction was precipitated in 80 mL of MeOH,

three times each. The isolated polymer was dried under house

3

ꢀ

vacuum for 1 day, then in a vacuum oven at 40 C for 2 days to

(

2-ethylhexyl) but-2-ynedioate (4.830 g, 14.27 mmol) was

1

yield 1.110 g of an off-white solid. H NMR (500 MHz, CDCl , δ,

ꢀ

3

added to the reaction ﬂask and stirred at 50 C for 24 h. The

volatiles were evaporated in vacuo affording a colorless crude

oil. Puriﬁcation via ﬂash chromatography using 7:3 hexanes:

ethyl acetate afforded 5.264 g (10.93 mmol, 99.53% yield) of

a colorless oil, as a mixture of diastereomers. R : 0.29 (SiO ,

ppm): 8.25–8.20 (br m, PVC-triazole-H), 8.19–8.07 (br m,

PVC-triazole-H), 5.26–5.10 (br m, C-CH-triazole), 4.65–4.52 (br m,

Cl-C-H and PVC-linker-C-CH

.40–4.22 (br m, Cl-C-H and PVC-triazole-O-CH

inker-triazole-O-CH ), 2.87–2.79 (br m, Cl-C-CH -C-triazole and

2

-triazole), 4.45 (br s, Cl-C-H),

4

2

-linker and PVC-l

f

2

1

2

hexanes:ethyl acetate, 7:3). H NMR (500 MHz, CDCl

3

, δ, ppm):

triazole-C-CH -C-triazole), 2.78–2.69 (br s, Cl-C-CH -C-triazole and

2

4.58 (t, J = 7.3 Hz, 2H), 4.33–4.22 (m, 4H), 3.63 (t, J = 6.5 Hz,

triazole-C-CH

2

-C-triazole), 2.68–2.51 (br m, Cl-C-CH

2

-C-triazole

-C-Cl),

-C-triazole), 1.85–1.77 (br s,

-linker), 1.76–1.65 (br m, PVC-linker-triazol

e-O-C-CH-C), 1.55–1.25 (br m, linker CH ’s and linker-triazol

2

H), 1.91 (p, J = 7.5 Hz, 2H), 1.77–1.64 (m, 2H), 1.55 (p,

and triazole-C-CH

.98–1.86 (br s, PVC-linker-CH

PVC-triazole-O-C-CH

2 2

-C-triazole), 2.50–1.99 (br m, Cl-C-CH

1

3

J = 6.6 Hz, 2H), 1.44–1.26 (m, 21H), 0.97–0.80 (m, 12H).

C

1

2

NMR (125 MHz, CDCl , δ, ppm): 160.5 (C O), 158.8 (C O),

3

ꢀ ꢀ

40.4 (4 ), 129.7 (4 ), 69.1 (CH ), 68.3 (CH ), 62.5 (CH ), 50.4

2 2 2

2

1

2

(

CH ), 38.7 (CH), 38.7 (CH), 32.4 (CH ), 30.2 (CH ), 28.9

2

13

e-O-C-C-CH -CH -CH -C), 0.97–0.86 (br m, CH₃).

C

NMR

2

CH

), 26.1 (CH

), 14.0 (CH

2

), 25.1 (CH

2 2 2

), 23.6 (CH ), 23.5 (CH ), 22.9

(

125 MHz, CDCl , δ, ppm): 160.6 (C O), 158.8 (C O), 140.4

−

1

3

), 10.9 (CH ). IR (NaCl, neat, cm ): 3436 (s,

3

ꢀ

(

4 ), 129.6 (4 ), 69.2 (O-CH

7.1–56.9 (CH syndio), 56.1–55.9 (CH hetero), 55.0–54.9

CH iso), 50.4 (CH ), 47.3–44.8 (family of CH PVC peaks), 38.72

CH), 38.69 (CH), 30.19 (CH ), 30.16 (CH ), 30.1 (CH ), 28.88

2 2 2

), 68.4 (O-CH ), 65.2 (O-CH ),

OH), 2959 (s, alkane CH), 2932 (s, alkane CH), 2861 (s, alkane

CH), 1733 (s, ester C O), 1555 (m, triazole C C), 1466 (s,

5

(

2

methylene bending CH ), 1279 (m, ester stretch C–O), 1060

2

ꢀ

2

(

4

1

alcohol stretch C–O). HRMS (m/z): calcd for C H N O

6 47 3 5

2

(

CH ), 28.86 (CH ), 28.4 (CH ), 26.0 (CH ), 25.4 (CH ), 23.6

+

2 2 2 2 2

82.3588; found, 482.3588 [M + H] .

(

CH ), 23.5 (CH ), 22.96 (CH ), 22.94 (CH ), 14.1 (CH ), 10.9

2 2 2 2 3

−1

3

(CH ). IR (NaCl, thin ﬁlm, cm ): 3139 (w, triazole CH), 2960

Preparation of 4,5-bis(2-Ethylhexyl)-1-[6-(Prop-2-Ynoyloxy)

Hexyl]-1H-1,2,3-Triazole-4,5-Dicarboxylate (6c)

(s, alkane CH), 2932 (s, alkane CH), 2861 (s, alkane CH), 1733

(s, ester C O), 1552 (m, triazole C C), 1465 (m, methylene

Propiolic acid (0.500 g, 7.138 mmol) was added to a 25 mL

round-bottom ﬂask with 7 mL of toluene. 4,5-Bis(2-ethyl-

hexyl) 1-(6-hydroxyhexyl)-1H-1,2,3-triazole-4,5-dicarboxylate

stretch CH

C–O), 616 (w, C–Cl). DSC (T

2

), 1436 (m, methyl stretch CH), 1202 (s, ester stretch

ꢀ

): 41 C.

g

(

4.126 g, 8.565 mmol) and 4-methylbenzenesulfonic acid

0.082 g, 0.428 mmol) was added to the reaction ﬂask and

PEO Type 1 Syntheses

Preparation of 4,5-bis({2-[2-(2-Methoxyethoxy)Ethoxy]

Ethyl}) 1-(6-Hydroxyhexyl)-1H-1,2,3-Triazole-

4,5-Dicarboxylate (5d)

stirred at reﬂux for 2 h. The volatiles were evaporated in

vacuo, affording a light-brown crude oil. Puriﬁcation via ﬂash

chromatography using 4:1 hexanes:ethyl acetate afforded

6-Azidohexan-1-ol (1.000 g, 6.983 mmol) was added

2

.7286 g (5.1126 mmol, 71.64% yield) of a colorless oil, as a

mixture of diastereomers. R : 0.56 (SiO , hexanes:ethyl acetate,

:1). H NMR (500 MHz, CDCl , δ, ppm): 4.59 (t, J = 7.3 Hz,

3

to a 100 mL round-bottom ﬂask with 30 mL of CHCl . 1,4-

Bis({2-[2-(2-methoxyethoxy)ethoxy]ethyl})but-2-ynedioate

f

2

1

4

2

1

0

(3.406 g, 8.381 mmol) was added to the reaction ﬂask and

3

ꢀ

H), 4.35–4.23 (m, 4H), 4.19 (t, J = 6.6 Hz, 2H), 2.90 (s, 1H),

.93 (p, J = 7.3 Hz, 2H), 1.71 (m, 4H), 1.50–1.27 (m, 20H),

.96–0.87 (m, 12H). C NMR (125 MHz, CDCl

stirred at 50 C for 24 h. The volatiles were evaporated in

vacuo affording a colorless crude oil. Puriﬁcation via ﬂash

1

3

, δ, ppm): 160.5

chromatography using 95:5 CH

2 2

Cl :MeOH afforded 2.853 g

ꢀ

(

C O), 158.8 (C O), 152.7 (C O), 140.5 (4 ), 129.6 (4 ), 74.7

(5.191 mmol, 74.34% yield) of the title compound as a colorless

ꢀ

1

alkyne 4 ), 74.6 (alkyne CH), 69.2 (CH

2

), 68.4 (CH

), 38.73 (CH), 38.70 (CH), 30.20 (CH

CH ), 30.1 (CH ), 28.9 (CH ), 28.9 (CH ), 28.1 (CH ), 26.0

2

), 66.0

f 2 2 2 3

oil. R : 0.48 (SiO , CH Cl :MeOH, 95:5). H NMR (500 MHz, CDCl ,

CH

2

), 50.3 (CH

2

), 30.15

δ, ppm): 4.60 (t, J = 7.2 Hz, 2H), 4.55 (t, J = 4.5, 2H), 4.51

(t, J = 4.9 Hz, 2H), 3.82 (overlapping t, J = 4.8 Hz, 4H), 3.72–3.60

(m, 14H), 3.56–3.53 (m, 4H), 3.37–3.36 (m, 6H), 1.93 (p, J

2

CH ), 25.3 (CH ), 23.6 (CH ), 23.5 (CH ), 22.94 (CH ), 22.93

CH ), 14.0 (CH ), 10.88 (CH ), 10.87 (CH ). IR (NaCl, neat,

2

= 7.2 Hz, 2H), 1.69 (s, 1H), 1.56 (p, J = 6.7 Hz, 2H), 1.47–1.30 (m,

2

3

−

1

13

cm ): 3255 (s, alkyne CH), 2960 (s, alkane CH), 2931 (s,

alkane CH), 2862 (s, alkane CH), 2117 (s, alkyne CC), 1717 (s,

ester C O), 1555 (m, triazole C C), 1465 (s, methylene bend-

ing CH ), 1268 (s, ester stretch C–O), 1220 (s, ester stretch C–

O). HRMS (m/z): calcd for C H N O 534.3538; found,

4H). C NMR (125 MHz, CDCl

3

, δ, ppm): 160.1 (C O), 158.5

), 70.7 (CH ), 70.6 (CH ),

), 68.8 (CH ), 68.5 (CH ), 65.6

(CH ), 64.8 (CH ), 62.5 (CH ), 59.0 (CH ), 50.5 (CH ), 32.4 (CH ),

ꢀ

(C O), 140.0 (4 ), 130.1 (4 ), 71.9 (CH

70.6 (CH ), 70.6 (CH ), 70.5 (CH

2

3

2

−1

30.1 (CH ), 26.0 (CH ), 25.1 (CH ). IR (NaCl, neat, cm ): 3472

2 2 2

2

9

47

3

6

+

5

34.3521 [M + H] .

(s, OH), 2930 (s, alkane CH), 2874 (s, alkane CH), 1733 (s, ester

JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2018

5

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C O), 1552 (m, triazole C C), 1468 (s, methylene bending CH

2

),

C-triazole), 2.51–2.00 (br m, Cl-C-CH

2

-C-Cl), 1.86–1.72 (br m,

1

281 (s, ester stretch C–O), 1247 (s, ether stretch C–O), 1111 (s,

PVC-linker-CH -C-triazole), 1.72–1.62 (br s, PVC-triazole-O-C-

2

ꢀ

13

ether stretch C–O), 1067 (s, 1 alcohol stretch C–O). HRMS (m/z):

calcd for C24

CH -linker), 1.56–1.33 (br m, linker CH ’s).

C NMR

2

+

H

43

N

3

O

11 550.2970; found, 550.2948 [M + H] .

(125 MHz, CDCl

3

, δ, ppm): 160.2 (C O), 158.4 (C O), 71.9

), 70.61 (CH ), 70.57 (CH ), 68.8 (CH ), 68.5

), 65.7 (CH ), 64.8 (CH ), 59.0 (CH ), 57.0–56.9

), 47.3–44.8 (family of CH peaks), 30.0

), 26.0 (CH ), 25.4 (CH ). IR (NaCl, thin ﬁlm,

(

CH

2

), 70.67 (CH

2

Preparation of 4,5-bis({2-[2-(2-Methoxyethoxy)Ethoxy]

Ethyl})-1-[6-(Prop-2-Ynoyloxy)Hexyl]-1H-1,2,3-Triazole-

4

Propiolic acid (1.000 g, 14.276 mmol) was added to a 50 mL

round-bottom ﬂask with 14 mL of toluene. 4,5-Bis

(CH

2

3

(CH syndio), 50.5 (CH

(CH ), 28.4 (CH

2

,5-Dicarboxylate (6d)

2

−

1

cm ): 3137 (w, triazole CH), 2936 (s, alkane CH), 2874 (s,

alkane CH), 1733 (s, ester C O), 1551 (m, triazole C C),

(

1

{2-[2-(2-methoxyethoxy)ethoxy]ethyl})-1-(6-hydroxyhexyl)-

H-1,2,3-triazole-4,5-dicarboxylate (9.415 g, 17.131 mmol)

2

1466 (s, methylene stretch CH ), 1438 (s, methyl stretch CH),

1247 (s, ester stretch C–O), 1203 (s, ester stretch C–O), 1121

ꢀ

and 4-methylbenzenesulfonic acid (0.272 g, 1.428 mmol) was

added to the reaction ﬂask and stirred at reﬂux for 3 h. The

volatiles were evaporated in vacuo, affording a light-brown

crude oil. Puriﬁcation via ﬂash chromatography using 95:5

CH Cl :MeOH afforded 6.612 g (10.990 mmol, 76.98% yield)

of the title compound as a colorless oil. R : 0.50 (SiO , CH Cl :

MeOH, 95:5). H NMR (500 MHz, CDCl

J = 7.2 Hz, 2H), 4.54 (t, J = 4.8, 2H), 4.50 (t, J = 4.9 Hz, 2H),

4

3

2

1

(

(s, ether stretch C–O), 615 (w, C–Cl). DSC (T

g

): 18 C.

Alkyl Type 2 Syntheses

Preparation of Dibromofumaric Acid (8)

5

0

2

Acetylenedicarboxylic acid monopotassium salt (5.522 g,

36.30 mmol) was added to a 500 mL round-bottom ﬂask and

dissolved into ~20 mL of 2 M aqueous KOH solution while stir-

ring. NaBr (102.89 g, 26.149 mmol) was dissolved in 80 mL of

H O via sonication. Br (6.381 g, 39.93 mmol) was quickly added

f

2

1

3

, δ, ppm): 4.59 (t,

.18 (t, J = 6.5 Hz, 2H), 3.82 (overlapping t, J = 4.9 Hz, 4H),

.72–3.60 (m, 12H), 3.57–3.49 (m, 4H), 3.37 (s, 3H), 3.36 (s,

H), 2.93 (s, 1H), 1.93 (p, J = 7.2 Hz, 2H), 1.68 (p, J = 6.5 Hz,

2

to the NaBr aqueous solution. The resulting orange NaBr/Br₂

solution was subsequently added to the acetylenedicarboxylate

solution. Stirring was ceased for the remainder of the reaction to

1

3

H), 1.45–1.34 (m, 4H). C NMR (125 MHz, CDCl , δ, ppm):

3

ꢀ

60.1 (C O), 158.4 (C O), 152.7 (C O), 140.0 (4 ), 129.6

4 ), 74.7 (alkyne 4 ), 74.6 (alkyne CH), 71.9 (CH

prevent Br degradation. The reaction ﬂask was covered in alu-

2

ꢀ

2

), 70.7

minum foil, and an additional 50 mL of H O was added to bring

2

CH

2

), 70.60 (CH

), 65.6 (CH

2

), 70.56 (CH

2

), 68.8 (CH

2

), 68.5 (CH ), 66.0

2

), 50.4 (CH ), 30.0

2

the total volume to 150 mL, and was left for 24 h at room tem-

perature. After 24 h, a transparent colorless solution was

observed. To the reaction ﬂask, 3 mL of saturated aqueous

NaHSO solution was added to quench the excess Br while stir-

2

), 64.8 (CH ), 59.0 (CH

2

3

CH ), 28.1 (CH ), 25.9 (CH ), 25.2 (CH ). IR (NaCl, neat,

2

−

1

cm ): 3220 (m, alkyne CH), 2874 (s, alkane CH), 2114 (s,

alkyne CC), 1732 (s, ester C O), 1715 (s, ester C O), 1552

(

stretch C–O), 1235 (s, ester stretch C–O), 1108 (s, ether

stretch C–O). HRMS (m/z): calcd for C27

3

2

ring. The reaction was saturated with NaCl and acidiﬁed with

12 mL of concentrated HCl and extracted with 50 mL of ethyl

acetate each four times. The organic layers were dried with

Na SO . The volatiles were evaporated in vacuo to afford a white

triazole C C), 1469 (methylene bending CH

2

), 1271 (m, ester

H

43

N

3

O12 602.2920;

2

4

+

found, 602.2917 [M + H] .

solid. After recrystallization in chloroform, 8.000 g (29.21 mmol,

0.47% yield) of the title compound was recovered as colorless

8

ꢀ

needles. mp 239–240 C. C NMR (125 MHz, d -Acetone, δ,

6

13

Preparation of 15% PVC-TRZ-Hexyl-TRZ-DiPEO₁₆₄Me (7d)

Poly(vinyl chloride) 15% azide (1.000 g, 16.00 mmol) was

added to a 100 mL round-bottom ﬂask and dissolved in

3

−1

ppm): 162.8 (C O), 111.7 (C–Br). IR (KBr pellet, cm ): 3013 (s,

OH stretch), 1699 (s, carboxylic acid C O), 1405 (m, alcohol

bending OH), 686 (m, C–Br).

ꢀ

0 mL of 3-pentanone at 90 C. 4,5-Bis({2-[2-(2-methox-

yethoxy)ethoxy]ethyl})-1-[6-(prop-2-ynoyloxy)hexyl]-1H-1,2,3-

triazole-4,5-dicarboxylate (3.610 g, 6.000 mmol) was added to

the PVC solution and stirred for 24 h. The reaction was con-

centrated to approximately half its volume in vacuo, then pre-

cipitated in 80 mL of MeOH, three times each. The isolated

polymer was dried under house vacuum for 1 day, then in a

Preparation of 4,5-bis(2-Ethylhexyl) 1-(6-{[(2E)-

4-({6-[4,5-bis({[(2-Ethylhexyl)Oxy]Carbonyl})-1H-

1,2,3-Triazol-1-Yl]Hexyl}Oxy)-2,3-Dibromo-4-Oxobut-

2-Enoyl]Oxy}Hexyl)-1H-1,2,3-Triazole-

4,5-Dicarboxylate (10c)

Dibromofumaric acid (1.520 g, 5.550 mmol) and PCl

5

ꢀ

vacuum oven at 40 C for 2 days to yield in a vacuum oven at

ꢀ

1

4

(

5

0 C for 3 days to yield 1.920 g of a white solid. H NMR

500 MHz, CDCl , δ, ppm): 8.35–8.05 (br m, PVC-triazole-H),

.32–5.12 (br m, C-CH-triazole), 4.70–4.59 (br m, Cl-C-H and

(2.427 g, 11.655 mmol) were added to a 25 mL round-bottom

ﬂask with 5 mL of pentane. The reaction was reﬂuxed for 2 h

while stirring. Reaction completeness was determined by

observing the dissolution of solids into a clear yellow solution.

After the dissolution of solids was noted, the reaction was

immediately diluted with 5 mL of pentane. The diluted reac-

tion was added slowly to a 150 mL beaker of crescent-cube

ice, and was allowed to stand for 10 min with occasional swir-

ling. The quenched reaction solution was transferred to a

150 mL separatory funnel. The organic layer was collected

and dried with Na SO . The volatiles were evaporated in

3

PVC-linker-C-CH -triazole), 4.58–4.54 (br s, Cl-C-H and tria-

2

zole-O-CH -C-O), 4.54–4.50 (br m, Cl-C-H and triazole-O-CH -C-

2

O), 4.49–4.42 (br s, Cl-C-H), 4.41–4.26 (br m, Cl-C-H and PVC-

triazole-O-CH -linker), 3.90–3.81 (br m, triazole-O-C-CH -O),

.73–3.62 (br m, triazole-O-C-C-O-CH -CH -O-CH -C), 3.58–3.53

br m, C-CH -O-CH ), 3.39 (br s, O-CH ), 3.38 (br s, O-CH ),

2

3

2

(

2

3

2

.87–2.79 (br s, Cl-C-CH -C-triazole and triazole-C-CH -C-tria-

2

zole), 2.78–2.61 (br m, Cl-C-CH -C-triazole and triazole-C-CH -

2

4

6

JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2018

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ORIGINAL ARTICLE

vacuo, affording a clear yellow oil (1.656 g, 5.329 mmol,

6.02% yield) of (2E)-dibromobut-2-enedioyl dichloride. The

acid chloride was immediately diluted with 30 mL of CCl₄

under N in a 250 mL pear ﬂask. Next, 4,5-bis(2-ethylhexyl)

-(6-hydroxyhexyl)-1H-1,2,3-triazole-4,5-dicarboxylate (5.392 g,

1.193 mmol) and pyridine (0.885 g, 11.193 mmol) were

4H), 1.74–1.63 (m, 8H), 1.48–1.28 (m, 40H), 0.91–0.87 (m, 24H).

13

9

C NMR (125 MHz, CDCl , δ, ppm): 160.6 (C O), 158.8 (C O),

3

ꢀ

151.8 (C O), 140.5 (4 ), 129.6 (4 ), 74.7 (alkyne 4 ), 69.2 (CH ),

2

68.4 (CH

(CH ), 30.0 (CH

23.6 (CH ), 23.6 (CH

(NaCl, neat, cm ): 2959 (s, alkane CH), 2932 (s, alkane CH),

2872 (s, alkane CH), 2862 (s, alkane CH), 1727 (s, ester C O),

2

), 66.7 (CH

), 28.9 (CH

), 23.0 (CH

2

), 50.3 (CH

), 28.1 (CH

), 14.1 (CH

2

), 38.7 (CH), 30.2 (CH

), 25.9 (CH ), 25.2 (CH

), 10.9 (CH ). IR

2

), 30.2

1

2

),

2

3

−

1

added to a 250 mL round-bottom ﬂask with 60 mL of CCl

4

ꢀ

and cooled to 0 C under N with stirring. The acid chloride

2

solution was slowly added via syringe over 10 min, noting an

orange–brown color and the formation of pyridine salts in

solution. After the addition of the acid chloride, the reaction

1554 (m, triazole C C), 1466 (s, methylene bending CH ), 1256

2

(s, ester stretch C–O), 1215 (s, ester stretch C–O). HRMS (m/z):

+

calcd for C56

H

92

N

6

O

12 1041.6846; found 1041.6843, [M + H] .

ꢀ

was allowed to stir at 0 C for 30 min, then at room tempera-

ture for an additional 2 h. The reaction was poured into a

Preparation of 15% PVC-TRZ-DiHexyl-TRZ-DiEH (12c)

Poly(vinyl chloride) 15% azide (1.000 g, 16.00 mmol) was

added to a 100 mL round-bottom ﬂask and dissolved in

500 mL separatory funnel and washed with 20 mL of 5%

aqueous HCl, two times each. The organic layer was collected,

ꢀ

dried with MgSO , and ﬁltered. The volatiles were then evapo-

20 mL of 3-pentanone at 90 C. 4,5-Bis(2-ethylhexyl)

4

rated in vacuo, affording a dark-red oil. Puriﬁcation via ﬂash

chromatography using 7:3 hexanes:ethyl acetate was per-

formed, affording 5.146 g (4.284 mmol, 80.38% yield) of a col-

1-(6-{[4-({6-[4,5-bis({[(2-ethylhexyl)oxy]carbonyl})-1H-1,2,3-tria-

zol-1-yl]hexyl}oxy)-4-oxobut-2-ynoyl]oxy}hexyl)-1H-1,2,3-tria-

zole-4,5-dicarboxylate (7.498 g, 7.200 mmol) was added to

the PVC solution and stirred for 28 h. The reaction was

concentrated to approximately half its volume in vacuo and

precipitated in 80 mL of MeOH, four times each. The poly-

mer was dried under house vacuum for 1 day, then in a

orless oil, as a mixture of diastereomers. R

hexanes:ethyl acetate, 7:3). H NMR (500 MHz, CDCl , δ, ppm):

f

: 0.64 (SiO

2

,

1

3

4

.55 (t, J = 7.3 Hz, 4H), 4.30–4.19 (m, 12H), 1.89 (p, J = 7.4 Hz,

H), 1.73–1.62 (m, 8H), 1.47–1.21 (m, 40H), 0.93–0.79

1

3

ꢀ

(

1

(

m, 24H). C NMR (125 MHz, CDCl

60.6 (C O), 158.8 (C O), 140.5 (4 ), 129.6 (4 ), 112.7

C-Br), 69.1 (CH ), 68.4 (CH ), 66.9 (CH ), 50.3 (CH ), 38.7

CH), 30.2 (CH ), 30.2 (CH ), 30.1 (CH ), 28.9 (CH ), 28.1 (CH ),

3

, δ, ppm): 162.2 (C O),

vacuum oven at 40 C for 3 days to yield 2.397 g of a ﬂexi-

ꢀ

1

ble pale yellow solid. H NMR (500 MHz, CDCl

3

, δ, ppm):

5.63–5.34 (br m, C-CH-triazole), 4.67–4.52 (br m, Cl-C-H

and PVC-linker-C-CH -triazole), 4.51–4.38 (br m, Cl-C-H and

PVC-triazole-O-CH -linker and PVC-linker-triazole-O-CH -C),

4.38–4.15 (br m, Cl-C-H), 2.92–2.80 (br s, Cl-C-CH -C-tria-

zole and triazole-C-CH -C-triazole), 2.80–2.66 (br s, Cl-C-

CH -C-triazole and triazole-C-CH -C-triazole), 2.50–1.98

(br m, Cl-C-CH -C-Cl), 1.98–1.87 (br s, PVC-linker-CH -C-

triazole), 1.84–1.64 (br m, PVC-triazole-O-C-CH -linker and

PVC-linker-triazole-O-C-CH-C), 1.54–1.24 (br m, linker CH ’s

and linker-triazole-O-C-C-CH -CH -CH -C), 0.98–0.83 (br m,

CH₃). C NMR (125 MHz, CDCl , δ, ppm): 160.6 (C O),

2

5.9 (CH ), 25.2 (CH ), 23.6 (CH ), 23.5 (CH ), 22.9 (CH ), 14.0

2

−1

(

CH ), 10.9 (CH ). IR (NaCl, neat, cm ): 2959 (s, alkane CH),

2

3

2

1

932 (s, alkane CH), 2872 (s, alkane CH), 2861 (s, alkane CH),

736 (s, ester C O), 1554 (m, triazole C C), 1466 (s, methy-

2

lene bending CH ), 1267 (s, ester stretch C–O), 1235 (s, ester

2

stretch C–O), 758 (m, alkene bending C C). HRMS (m/z): calcd

2

+

for C H Br N O 1199.5213; found, 1199.5212 [M + H] .

2

5

6

92

2 6 12

+

(Br isotopes): 1201.5193, 1203.5179, 1204.5198 [M + H] .

2

1

3

ꢀ

Preparation of 4,5-bis(2-Ethylhexyl) 1-(6-{[4-({6-[4,5-bis

{[(2-Ethylhexyl)Oxy]Carbonyl})-1H-1,2,3-Triazol-1-Yl]Hexyl}

Oxy)-4-Oxobut-2-Ynoyl]Oxy}Hexyl)-1H-1,2,3-Triazole-

,5-Dicarboxylate (11c)

To 250 mL round-bottom ﬂask, 4,5-bis(2-ethylhexyl)

158.8 (C O), 140.5 (4 ), 129.6 (4 ), 69.1 (O-CH

CH ), 66.4 (O-CH ), 65.7 (O-CH ), 57.0–56.9 (CH syndio),

56.1–55.9 (CH hetero), 50.4 (CH ), 47.3–45.2 (family of

CH PVC peaks), 38.72 (CH), 38.68 (CH), 30.2 (CH ), 30.14

(CH ), 30.1 (CH ), 28.87 (CH ), 28.85 (CH ), 28.4 (CH

28.1 (CH ), 26.1 (CH ), 26.0 (CH ), 25.3 (CH ), 25.2 (CH

25.16 (CH ), 23.6 (CH ), 23.5 (CH ), 22.95 (CH

(CH ), 14.0 (CH ), 10.90 (CH ), 10.88 (CH ). IR (NaCl, thin

2

), 68.3 (O-

(

2

4

2

a

2

),

1

-(6-{[(2E)-4-({6-[4,5-bis({[(2-ethylhexyl)oxy]carbonyl})-1H-

,2,3-triazol-1-yl]hexyl}oxy)-2,3-dibromo-4-oxobut-2-enoyl]

2

), 22.93

oxy}hexyl)-1H-1,2,3-triazole-4,5-dicarboxylate (7.207 g, 6.000

mmol) was added to 60 mL of anhydrous THF. Subsequently, Zn

2

3

−

1

ﬁlm, cm ): 2960 (s, alkane CH), 2932 (s, alkane CH), 2861

metal (2.353 g, 36.00 mmol) and I

added and stirred at reﬂux for 5 h under N

2

(0.183 g, 0.721 mmol) were

(s, alkane CH), 1729 (s, ester C O), 1553 (s, triazole C C),

1465 (s, methylene stretch CH ), 1437 (m, methyl stretch

2

. The reaction was

cooled and ﬁltered through Celite™. The reaction was concen-

trated in vacuo and diluted with 80 mL of ethyl acetate. The solu-

tion was poured into a 500 mL separatory funnel and washed

CH), 1260 (s, ester stretch C–O), 1204 (s, ester stretch C–

ꢀ

O), 616 (w, C–Cl). DSC (T

): −6 C.

g

with 20 mL of 10% aqueous NaHSO , two times each. The

PEO Type 2 Syntheses

3

organic layer was collected and dried with MgSO . The volatiles

were then evaporated in vacuo, and immediately puriﬁed via

ﬂash chromatography using 7:3 hexanes:ethyl acetate, affording

Preparation of 4,5-bis({2-[2-(2-Methoxyethoxy)Ethoxy]

Ethyl}) 1-(6-{[(2E)-4-({6-[bis(2,5,8,11-Tetraoxadodecanoyl)-

1H-1,2,3-Triazol-1-Yl]Hexyl}Oxy)-2,3-Dibromo-4-Oxobut-

2-Enoyl]Oxy}Hexyl)-1H-1,2,3-Triazole-

4

5.322 g (5.111 mmol, 85.18% yield) of a colorless oil, as a mix-

ture of diastereomers. R : 0.63 (SiO , hexanes:ethyl acetate, 7:3).

4,5-Dicarboxylate (10d)

Dibromofumaric acid (1.500 g, 5.477 mmol) and PCl (2.394 g,

f

2

1

H NMR (500 MHz, CDCl , δ, ppm): 4.56 (t, J = 7.2 Hz, 4H),

3

5

4.31–4.22 (m, 8H), 4.19 (t, J = 6.6 Hz, 4H), 1.90 (p, J = 7.2 Hz,

11.501 mmol) were added to a 25 mL round-bottom ﬂask with

JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2018

7

JOURNAL OF

POLYMER SCIENCE

ORIGINAL ARTICLE

WWW.POLYMERCHEMISTRY.ORG

5

mL of pentane. The reaction was reﬂuxed for 2 h while stir-

was concentrated in vacuo and diluted with 80 mL of ethyl ace-

ring. Reaction completeness was determined by observing the

dissolution of solids into a clear yellow solution. After the disso-

lution of solids was noted, the reaction was immediately diluted

with 5 mL of pentane. The diluted reaction was added slowly to

a 150 mL beaker of crescent-cube ice, and was allowed to stand

for 10 min with occasional swirling. The quenched reaction solu-

tion was transferred to a 150 mL separatory funnel. The organic

layer was collected and dried with Na SO . The volatiles were

tate. The solution was poured into a 500 mL separatory funnel

and washed with 10 mL of 10% aqueous NaHSO , two times

3

each. The organic layer was collected and dried with MgSO

volatiles were then evaporated in vacuo, and immediately puriﬁed

via ﬂash chromatography using 95:5 CH Cl :MeOH, affording

4

. The

2

3.852 g (3.272 mmol, 83.79% yield) of the title compound as a

1

pale yellow oil. R : 0.47 (SiO , CH Cl :MeOH, 95:5). H NMR

f

2

2 2

(500 MHz, Benzene-d , δ, ppm): 4.36 (t, J = 4.9 Hz, 4H), 4.31 (t,

2

4

6

evaporated in vacuo affording a clear yellow oil (1.701 g,

.477 mmol, quantitative yield) of (2E)-dibromobut-2-enedioyl

dichloride. The acid chloride was immediately diluted with

0 mL of CCl under N in a 250 mL pear ﬂask. Next, 4,5-bis

{2-[2-(2-methoxyethoxy)ethoxy]ethyl})-1-(6-hydroxyhexyl)-1H-

,2,3-triazole-4,5-dicarboxylate (6.321 g, 11.501 mmol) and pyri-

J = 4.8 Hz, 4H), 4.09 (t, J = 7.3 Hz, 4H), 3.76 (t, J = 6.6 Hz, 4H),

3.47 (t, J = 4.9 Hz, 8H), 3.45–3.39 (m, 24H), 3.35–3.30 (m, 8H),

3.13 (s, 6H), 3.12 (s, 6H), 1.45 (p, J = 7.2 Hz, 4H), 1.10 (p,

5

13

3

(

1

4

2

J = 6.7 Hz, 4H), 0.87–0.80 (m, 8H). C NMR (125 MHz,

Benzene-d , δ, ppm): 160.6 (C O), 158.5 (C O), 151.6 (C O),

6

ꢀ ꢀ ꢀ

140.9 (4 ), 129.5 (4 ), 74.9 (alkyne 4 ), 72.0 (CH ), 70.6 (CH ),

2 2

dine (0.910 g, 11.501 mmol) were added to a 250 mL round-

70.6 (CH ), 70.49 (CH ), 70.48 (CH ), 70.46 (CH ), 68.7 (CH ),

2

ꢀ

bottom ﬂask with 60 mL of CCl

4

and cooled to 0 C under N

2

68.3 (CH

(CH ), 29.6 (CH

neat, cm ): 2874 (s, alkane CH), 1727 (s, ester C O), 1552 (m,

triazole C C), 1469 (s, methylene bending CH ), 1259 (s, ester

2

), 66.3 (CH

2

), 65.3 (CH

2

), 64.7 (CH

2

), 58.3 (CH

3

), 49.7

with stirring. The acid chloride solution was slowly added via

syringe over 10 min, noting a light-yellow color and the forma-

tion of pyridine salts in solution. After the addition of the acid

2

), 27.7 (CH

2

), 25.5 (CH

2

), 24.7 (CH ). IR (NaCl,

2

−1

2

ꢀ

chloride, the reaction was allowed to stir at 0 C for 2 h, then at

stretch C–O), 1110 (s, ether stretch C–O). HRMS (m/z): calcd for

+

room temperature for an additional 22 h. The reaction was

poured into a 500 mL separatory funnel and washed with

C H N O 1177.5610; found, 1177.5616 [M + H] .

5

2 84 6 24

2

0 mL 5% aqueous HCl two times each. The organic layer was

Preparation of 15% PVC-TRZ-DiHexyl-TRZ-

DiPEO164Me (12d)

collected, dried with MgSO , and ﬁltered. The volatiles were

4

then evaporated in vacuo. Puriﬁcation via ﬂash chromatography

Poly(vinyl chloride) 15% azide (1.000 g, 16.00 mmol) was

added to a 100 mL round-bottom ﬂask and dissolved in

30 mL of 3-pentanone at 90 C. 4,5-Bis({2-[2-(2-methox-

using 95:5 CH Cl :MeOH was performed, affording 5.262 g

2

ꢀ

(

3.935 mmol, 71.85% yield) of the title compound as a colorless

1

oil. R : 0.47 (SiO , CH Cl :MeOH, 95:5). H NMR (500 MHz,

yethoxy)ethoxy]ethyl}) 1-(6-{[4-({6-[bis(2,5,8,11-tetraoxadodeca

noyl)-1H-1,2,3-triazol-1-yl]hexyl}oxy)-4-oxobut-2-ynoyl]oxy}hexy

l)-1H-1,2,3-triazole-4,5-dicarboxylate (7.064 g, 6.000 mmol) was

added to the PVC solution and stirred for 24 h. The reaction was

concentrated to approximately one-third its volume in vacuo. To

a 250 mL beaker, 100 mL of MeOH was added and then placed

in a dry ice-acetone bath for 2 min. The polymer was precipi-

tated by dropwise addition of the reaction solution in 2 mL

increments into the cooled MeOH. After the addition of reaction

solution, the mother liquor was decanted and replaced with

f

2

6

Benzene-d , δ, ppm): 4.36 (t, J = 4.9, 4H), 4.30 (t, 4H), 4.11 (t,

J = 7.3 Hz, 4H), 3.91 (t, J = 6.5 Hz, 4H), 3.50–3.45 (m, 8H),

3

1

8

1

7

6

.45–3.39 (m, 24H), 3.36–3.30 (m, 8H), 3.13 (s, 6H), 3.12 (s, 6H),

.49 (p, J = 7.4 Hz, 4H), 1.22 (p, J = 6.6 Hz, 4H), 1.00–0.84 (m,

1

3

H). C NMR (125 MHz, Benzene-d , δ, ppm): 162.0 (C O),

6

ꢀ

60.6 (C O), 158.5 (C O), 141.0 (4 ), 129.5 (4 ), 112.9 (C-Br),

2.0 (CH ), 71.98 (CH ), 70.63 (CH ), 70.59 (CH ), 70.51 (CH ),

0.50 (CH

5.3 (CH

CH ), 25.5 (CH

alkane CH), 1733 (s, ester C O), 1552 (m, triazole C C), 1468

2

), 70.47 (CH

2

), 68.7 (CH

2

), 68.3 (CH

2

), 66.7 (CH

),

2

), 64.7 (CH

2

), 58.3 (CH

3

), 49.7 (CH

2

), 29.6 (CH

2

), 27.8

−1

ꢀ

(

2

), 24.9 (CH

2

). IR (NaCl, neat, cm ): 2874 (s,

100 mL of fresh MeOH. The beaker was cooled to −78 C for

2 min, upon which another 2 mL of reaction solution was added

dropwise. This process was repeated until the entire polymer

was precipitated. When all the reaction solution was precipi-

tated, the last volume of mother liquor was decanted. Subse-

(

methylene bending CH ), 1270 (s, ester stretch C–O), 1242 (s,

2

ester stretch C–O), 1111 (s, ether stretch C–O), 755 (m, alkene

bending C C). HRMS (m/z): calcd for

52 2 6 24

C H84Br N O

+

ꢀ

1335.3976; found, 1335.3981 [M + H] .

quently, the neat polymer was cooled to −78 C and washed

with 50 mL of MeOH four times each. The isolated polymer was

Preparation of 4,5-bis({2-[2-(2-Methoxyethoxy)Ethoxy]

Ethyl}) 1-(6-{[4-({6-[bis(2,5,8,11-Tetraoxadodecanoyl)-1H-

dried under house vacuum for 1 day, then in a vacuum oven at

ꢀ

40 C for 3 days to yield 3.382 g of a ﬂexible pale yellow solid.

1

,2,3-Triazol-1-Yl]Hexyl}Oxy)-4-Oxobut-2-Ynoyl]Oxy}Hexyl)-

H-1,2,3-Triazole-4,5-Dicarboxylate (11d)

H NMR (500 MHz, CDCl , δ, ppm): 5.65–5.35 (br m, C-CH-tria-

3

zole), 4.67–4.58 (br s, Cl-C-H and PVC-linker-C-CH -triazole),

2

To a 250 mL round-bottom ﬂask, 4,5-bis({2-[2-(2-methox-

yethoxy)ethoxy]ethyl}) 1-(6-{[(2E)-4-({6-[bis(2,5,8,11-tetraoxa-

dodecanoyl)-1H-1,2,3-triazol-1-yl]hexyl}oxy)-2,3-dibromo-4-oxo-

but-2-enoyl]oxy}hexyl)-1H-1,2,3-triazole-4,5-dicarboxylate (5.221

g, 3.905 mmol) was added to 40 mL of anhydrous THF. Subse-

4.58–4.54 (br s, Cl-C-H and triazole-O-CH -C-O), 4.54–4.48 (br m,

2

Cl-C-H and triazole-O-CH

PVC-triazole-O-CH -linker), 3.88–3.78 (br m, triazole-O-C-CH

3.75–3.60 (br m, triazole-O-C-C-O-CH -CH -O-CH -C), 3.59–3.48

(br m, C-CH -O-CH ), 3.43–3.31 (br s, O-CH ), 2.90–2.80 (br s,

2

-C-O), 4.39–4.24 (br m, Cl-C-H and

2

-O),

2

3

quently, Zn metal (1.532 g, 23.432 mmol) and I (0.047 g, 0.1

Cl-C-CH -C-triazole and triazole-C-CH -C-triazole), 2.80–2.53

2 2

2

8

5 mmol) were added and stirred at reﬂux for 5 h under N . The

(br m, Cl-C-CH -C-triazole and triazole-C-CH -C-triazole),

2

reaction was cooled and ﬁltered through Celite™. The reaction

2

2.50–1.90 (br m, Cl-C-CH -C-Cl), 1.89–1.60 (br m,

8

JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2018

JOURNAL OF

POLYMER SCIENCE

WWW.POLYMERCHEMISTRY.ORG

ORIGINAL ARTICLE

PVC-linker-CH

2

-C-triazole

and

PVC-triazole-O-C-CH

2

-linker),

the last volume of mother liquor was decanted. Subsequently,

the neat polymer was cooled to −78 C and washed with

50 mL of MeOH four times each. The isolated polymer was

1

3

ꢀ

1.57–1.30 (br m, linker CH ’s). C NMR (200 MHz, CDCl , δ,

2

3

ꢀ

ppm): 160.1 (C O), 158.4 (C O), 140.0 (4 ), 129.9 (4 ), 129.5

ꢀ

(

4 ), 71.9 (CH

2

), 70.67 (CH

), 66.2 (CH ), 65.6 (CH

6.9 (CH syndio), 55.9 (CH hetero), 55.0–54.9 (CH iso), 50.5

), 47.3–44.8 (family of CH peaks), 30.0 (CH ), 29.7 (CH ),

8.4 (CH ), 28.1 (CH ), 26.04 (CH ), 25.96 (CH ), 25.3 (CH ),

2

), 70.60 (CH

2

), 70.56 (CH

2

), 68.8

dried under house vacuum for 1 day, then in a vacuum oven

ꢀ

(

5

CH

2

), 68.5 (CH

2

), 64.8 (CH

2

), 59.0 (CH

3

),

at 40 C for 3 days to yield 2.926 g of a ﬂexible transparent

1

yellow solid. H NMR (500 MHz, CDCl

3

, δ, ppm): 8.40–8.15

(CH

2

(br m, PVC-triazole-H), 5.35–5.05 (br m, C-CH-triazole),

4.65–4.55 (br s, Cl-C-H), 4.55–4.36 (br m, Cl-C-H and triazole-

2

−

1

5.2 (CH ). IR (NaCl, thin ﬁlm, cm ): 2928 (s, alkane CH), 2874

O-CH ), 4.36–4.15 (br m, Cl-C-H), 3.95–3.40 (br s, triazole-O-C-

2

(s, alkane CH), 1733 (s, ester C O), 1552 (m, triazole C C),

CH -O and triazole-O-C-C-O-CH -CH -O- and C-CH -O-CH ), 3.38

2

3

1

464 (s, methylene stretch CH

2

), 1279 (s, ester stretch C–O),

(br s, O-CH

Cl). C NMR (125 MHz, CDCl

3

), 3.36 (br s, O-CH

3

), 2.50–1.75 (br m, Cl-C-CH

, δ, ppm): 161.0 (C O), 72.5

), 68.9 (CH ), 63.0 (CH ), 61.7

), 57.0 (CH syndio), 55.9 (CH hetero), 54.9

peaks). IR (NaCl, thin ﬁlm,

2

-C-

1

3

1202 (s, ester stretch C–O), 1111 (s, ether stretch C–O), 615 (w,

ꢀ

C–Cl). DSC (T

g

): −17 C.

(CH

CH

2

), 71.9 (CH

), 59.0 (CH

2

), 70.6 (CH

2

(

2

3

Type 0M Syntheses

Preparation of Methoxy Poly(Ethylene Glycol) 2000 Prop-

2

(CH iso), 47.3–44.8 (family of CH

2

−

1

cm ): 3120 (w, triazole CH), 2871 (s, alkane CH), 1726 (m,

ester C O), 1544 (w, triazole C C), 1455 (m, methylene

-Ynoate (13b)

Propiolic acid (2.100 g, 30.00 mmol) was added to a 250 mL

round-bottom ﬂask with 40 mL of toluene. Methoxy

poly(ethylene glycol) 2000 (20.000 g, 10.00 mmol) and

stretch CH

stretch C–O), 615 (w, C–Cl). DSC (T

2

), 1251 (s, ester stretch C–O), 1111 (s, ether

ꢀ

g

): −42 C.

2 4

0.2 mL H SO was added to the reaction ﬂask and stirred at

reﬂux for 2 h. The reaction was concentrated in vacuo, and

diluted with 100 mL ethyl acetate. The solution was trans-

ferred to a 500 mL separatory funnel and washed with 10 mL

RESULTS AND DISCUSSION

Thermal azide-alkyne cycloaddition efﬁcacy is determined by

the energy gap between the highest occupied molecular

orbital (HOMO) of the alkyl azide and the lowest unoccupied

molecular orbital (LUMO) of the alkyne. Enhanced reactivity

is achieved by lowering the LUMO of the alkyne via adjacent

of saturated NaHCO three times each. The aqueous layer was

3

extracted with 100 mL ethyl acetate two times each. The

5

1

organic layers were combined and dried with MgSO

and concentrated in vacuo, affording 11.514 g (5.611 mmol,

6.11% gravimetric yield) of the title compound as a white

waxy solid of varying chain lengths. R : 0.45 (SiO , CH Cl :

4

, ﬁltered,

5

1–53

5

electron-withdrawing groups.

Selection of electron-

deﬁcient alkynes with functionalizable electron-poor esters

enabled cycloadditions to occur with PVC-azide under ther-

mal, copper-free conditions.

f

2

1

MeOH, 93:7). H NMR (500 MHz, CDCl , δ, ppm): 4.41–4.33

3

(

m, 2H), 3.84–3.78 (m, 1H), 3.77–3.73 (m, 2H), 3.73–3.61 (m,

1

2

76H), 3.59–3.54 (m, 2H), 3.54–3.47 (m, 1H), 3.42–3.35 (m,

1

3

45

H), 2.99 (s, 1H). C NMR (125 MHz, CDCl

3

, δ, ppm): 153.4

), 70.6

), 58.9

CH ). IR (NaCl, neat, cm ): 3216 (w, alkyne CH), 2876 (s,

Alkyne diesters were synthesized via Fischer esteriﬁcation

ꢀ

(

C O), 75.4 (alkyne 4 ), 74.7 (alkyne CH), 71.8 (CH

CH ), 70.5 (CH ), 68.5 (CH ), 65.1 (CH ), 60.3 (CH

2

followed by thermal dipolar cycloaddition to directly functio-

nalize PVC with a triazole-based phthalate mimic (Sch. 1).

Acetylenedicarboxylic acid was treated with either alkyl alco-

hols (n-butanol or 2-ethylhexyl alcohol) or monomethyl ethers

of polyethylene oxide (PEO) with n = 3, n ﬃ 7, and n ﬃ 11

polyether repeat units. Acid catalyst (p-toluenesulfonic acid,

for alkyl derivatives or sulfuric acid, for polyether derivatives)

was utilized in combination with toluene in a Dean-Stark

2

−

1

3

alkane CH), 2112 (m, alkyne CC), 1715 (m, ester C O), 1244

m, ester stretch C–O), 1111 (s, ether stretch C–O). HRMS (m/

z): calcd for (n 40) 42 1868.0589; found,

(

=

84 164

C H O

+

1

868.0557 [M + H] .

Preparation of 15% PVC-TRZ-PEO₂₀₀₀Me (14b)

apparatus. After 1–2 h under reﬂux, di(n-butyl) 2b,

Poly(vinyl chloride) 15% azide (1.000 g, 16.00 mmol) was

di(2-ethylhexyl) 2c, and three di(methoxy polyethylene oxide)

acetylenedicarboxylates 2d–f were obtained in satisfactory

yields. PVC-azide (azide displacement of chloride at either

5 or 15 mol %) was thermally cyclized with the alkyne dies-

ters. 3-Pentanone was the optimized solvent for these thermal

dipolar cycloadditions due to its relatively high boiling point,

yet has the ability to be evaporated in vacuo during workup.

added to a 100 mL round-bottom ﬂask and dissolved in

ꢀ

2

5 mL of 3-pentanone at 90 C. Methoxy poly(ethylene glycol)

000-prop-2-ynoate (7.387 g, 3.600 mmol) was added to the

PVC solution and stirred for 72 h. The reaction was concen-

trated to approximately half its volume in vacuo. To a 250 mL

beaker, 100 mL of MeOH was added and then placed in a dry

ice-acetone bath for 2 min. The polymer was precipitated by

dropwise addition of the reaction solution in 2 mL increments

into the cooled MeOH. After the addition of reaction solution,

the mother liquor was decanted and replaced with 100 mL of

ꢀ

Reactions were carried out at 90 C for 24 h, with 2.5–3.0

equivalents of electron-deﬁcient alkyne to each molar equiva-

lent of azide. Cycloadditions were monitored via FTIR, noting

−

1

the disappearance of the azide stretch at ~2110 cm and the

ꢀ

2

fresh MeOH. The beaker was cooled to −78 C for 2 min, upon

appearance of the triazole sp carbon–carbon stretch at

−

1

which another 2 mL of reaction solution was added dropwise.

This process was repeated until the entire polymer was pre-

cipitated. When all of the reaction solution was precipitated,

~1550 cm . After puriﬁcation, the ester carbonyl stretch at

−

1

~1730 cm was also indicative of the successful formation of

“Type 0D” triazole-phthalate mimics on PVC 3a–f.

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SCHEME 1 Synthesis of Type 0D triazole-phthalate mimics

attached to PVC.

Thermal measurements were obtained for each internally

plasticized polymer. Glass transition temperatures (T ) were

g

measured using differential scanning calorimetry (DSC) with

heat-cool-heat cycling to erase sample thermal history. Unmo-

ꢀ

diﬁed PVC exhibits a T

5 mol % gave T

g

of 81 C, while PVC-azide at 5 and

ꢀ

1

g

values of 83 and 78 C. Glass transition

temperatures of selected internally plasticized PVC samples

are given in Figure 3(a). T versus plasticizer weight percent

of these triazole plasticized polymers is illustrated in

Figure 3(b).

g

FIGURE 3 (a) Glass transition temperatures of selected triazole-

phthalate mimics. (b) Glass transition temperatures versus wt %

plasticizer.

Glass transition temperatures of all Type 0D alkyl functiona-

lized PVC samples are given in Supporting Information,

Figure S2(a). T_gversus plasticizer weight percent of these

covalently-bound triazole plasticized polymers is depicted in

Figure S2(b). Most alkyl functionalized Type 0D derivatives

that a tether between the triazole attachment to PVC (primary

triazole) and a triazole-phthalate mimic (secondary triazole)

would boost plasticizing efﬁciency by distancing the emollient

from the PVC main chain. This extension would maintain a

covalent attachment to PVC, while generating additional space

and mobility between the secondary triazole and the polymer.

The facile thermal azide-alkyne cycloaddition remained the

method of attachment to PVC for Type 1 and Type 2 triazole-

plasticizers.

3

g

b,c displayed moderate T depressions. However, 3a (PVC-

TRZ-DiMe) containing only methyl ester triazoles demonstrate

substantial anti-plasticization at 5 and 15 mol % internal plas-

ꢀ

ticizer (T 5 mol % = 88 C, T 15 mol % = 96 C, Fig. 3). This

g g

is likely due to the rigid aromatic nature of the triazole

anchor: π–π stacking of these triazole rings in the three-

dimensional matrix of PVC can impart crystallinity and stiff-

ness to the modiﬁed polymer. DSC data gathered from PVC

samples containing Type 0D alkyl emollients implies that plas-

ticization occurs, albeit inefﬁciently, due to the inability of the

triazole to move within the polymeric matrix, stemming from

anchoring the short alkyl triazole motif directly to PVC.

Selection of the tether was guided by synthetic accessibility

and structural simplicity (Sch. 2): the inexpensive hexyl tether

was chosen. Synthesis of the hexyl tether began with

6-chlorohexan-1-ol via an S 2 reaction using sodium azide in

N

ꢀ

49

DMSO at 50 C for 24 h. This led to 6-azidohexan-1-ol 4 in

quantitative yield, with no need for chromatographic puriﬁca-

tion. The azide 4 was combined with acetylenedicarboxylates

ꢀ

To compensate for anti-plasticization engendered by the

direct attachment of the rigid triazole, space was introduced

to enhance the ﬂexibility of the plasticizer. It was envisioned

2a–e in chloroform at 50 C for 24 h to give alcohols 5a–e

tethered to pendant triazole-phthalate mimics. High yields

(74%–99%) were achieved after column chromatography.

1

0

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SCHEME 2 Synthesis of alcohol tether with pendant triazole-

phthalate mimics.

Fischer esteriﬁcations were performed to obtain Type

1

electron-deﬁcient alkynes (Sch. 3). Propiolic acid was

combined with alcohols 5a–e, catalytic pTSA or H SO , and

2

4

toluene reﬂux in a Dean-Stark apparatus. The reactions

were complete after 2–3 h to form 6a–e, with yields rang-

ing from 60% to 77% after puriﬁcation. PVC-azide was

treated with propiolate esters 6a–e in 3-pentaone at

ꢀ

9

0

C. To monitor the process by FTIR, aliquots of the

reaction mixture were taken at 12 h intervals, and then

precipitated three times in methanol to remove the

unreacted propiolate ester. Cycloadditions with PVC-azide

were complete after 24 h, affording Type 1 internally plas-

ticized PVC 7a–e.

Alkyl functionalized Type 1 PVC 7a–c demonstrated moderate

glass transition temperature depressions [Supporting Informa-

tion, Fig. S3(a)]. T

g

versus plasticizer weight percent of Type

SCHEME 3 Synthesis of Type 1 and Type 0M triazole-phthalate

mimics attached to PVC.

1

PVC is given in [Supporting Information, Fig. S3(b)]. When

PEO164Me 7d and PEO350Me 7e were incorporated in the sec-

ondary triazole, both samples give T values similar to their

g

5

6

Type 1 alkyl relatives at 5 mol %. Miscibility of the internal

plasticizer in PVC plays a crucial role in effectively imparting

trivial task: Fischer esteriﬁcations, triazine,

carbodiimide

and

couplings were unsuccessful, largely due to

competing intramolecular Michael additions to the activated

5

7–59

5

4,55

ﬂexibility to the polymer.

Introduction of the hexyl tether

5

8,59

with 5 mol % PEO functionalized triazole esters in 7d,e does

acetylenedicarboxylate intermediates.

synthetic strategy

Modiﬁcation of a

involving the protection of the electron-

ꢀ

60,61

result in decreased T

g

values (7d T

g

= 57 C, 7e T

g

= 71 C)

compared to unmodiﬁed PVC [Supporting Information, Fig. S3

poor alkyne and subsequent acid chloride formation proved

successful in furnishing Type 2 alkynes (Sch. 4). Acetylenedi-

carboxylate monopotassium salt was protected by bromina-

tion. The acid chloride was obtained by treating

(

a)]. At 15 mol %, substantially lower T values of Type 1 PEO

g

ꢀ

triazole-plasticizers were observed: 7d (T = 18 C) and 7e

g

ꢀ

(T

g

= −1 C, Fig. 3).

dibromofumaric acid 8 with PCl . After workup on ice, dibro-

5

It was envisaged that one could further increase the weight

percentage of covalently bound plasticizer by synthesizing an

alkyne functionalized with two hexyl tethered triazoles. This

would further depress glass transition temperatures by intro-

ducing increased molecular weight and an additional branch

point compared to Type 1 plasticizers. Synthesis of Type

mofumaryl chloride 9 and alcohols 5a–d were combined to

afford the dibromofumarate esters 10a–d in 72%–86% yield.

Deprotection of 10a–d was accomplished by Zn/I , producing

2

Type 2 acetylenedicarboxylates 11a–d (80%–88%). According

to FTIR, cycloadditions between PVC-azide and 11a–d

ꢀ

required 24–36 h at 90 C, furnishing Type 2 internally plasti-

2

electron-deﬁcient acetylenedicarboxylates 11a–d was not a

cized PVC 12a–d.

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ꢀ

g

(T = −6 C) of any alkyl-based triazole internal plasticizer.

PEO functionalized 12d (PVC-TRZ-DiHexyl-TRZ-DiPEO₁₆₄Me)

displays diminished T values relative to the alkyl-based Type

g

ꢀ

2

derivatives (T

g

15 mol % = −17 C). As seen in Figure 3, this

also holds true against Type 1 7e containing PEO triazole

esters at both mole percentages.

These encouraging results prompted an investigation into

Type 0D PEO-functionalized triazoles as internal plasticizers

[

Supporting Information, Fig. S5(a,b)]. PEO chains signiﬁcantly

enhance T depressions with increasing length: 3d containing

triethylene oxide monomethyl ether (PEO164Me) displays only

a slight reduction in T compared to 3c [PVC-TRZ-DiEH; Sup-

porting Information, Fig. S2(a)]. Incorporation of longer PEO

g

−

1

chains with average molecular weights of 350 g mol in 3e

−

1

and 550 g mol in 3f exhibit striking glass transition temper-

ꢀ

ature depressions; most notably 3f (T

5 mol % (Fig. 3).

g

= −29 C) at

1

In a quest to minimize the number of synthetic steps to obtain

internally plasticized PVC, while further decreasing T values,

g

propiolates of large PEO monomethyl ethers were synthesized

(

Sch. 3). Fischer esteriﬁcation of propiolic acid and PEO (aver-

age molecular weight of 1000 or 2000 g/mol) gave PEO pro-

piolates 13a,b with yields of 56% and 77%. Cycloadditions to

PVC-azide were carried out with 13a,b, affording Type 0M

internally plasticized PVC 14a,b, as mixtures of major and

minor regioisomers.

Glass transition temperatures of Type 0M PEO plasticized PVC

are depicted in Figure 3(a), while T versus plasticizer weight

g

percent are given in Figure 3(b). Detailed thermal data of

Type 0M plasticized samples are illustrated in the Supporting

Information, Figure S6. Polymers 14a,b exhibit impressively

ꢀ

low T_gvalues at 15 mol %: 14a (T_g= −35 C) and 14b

ꢀ

(

T = −42 C).

g

Plasticization Efﬁciency

Plasticizing efﬁciencies of these new triazole internal plasti-

cizers were determined relative to the traditional DEHP-PVC

5

4

system utilized industrially. Plasticizer efﬁciency values

EΔT_g) were modiﬁed for this investigation using the

equation:

(

À

Á

EΔTg ¼ ΔTgTRZ=ΔTgDEHP × 100

ð1Þ

EΔT

g

corresponds to the difference in glass transition temper-

SCHEME

4 Synthesis of Type 2 triazole-phthalate mimics

ature between unmodiﬁed PVC and triazole-plasticized PVC

attached to PVC.

(

ΔT TRZ), divided by the T difference between unperturbed

g

PVC and an analogous weight percentage of DEHP plasticizer

This strategy was effective at enhancing glass transition tem-

perature depressions relative to alkyl-based Type 0D and

Type 1 internally plasticized PVC [Supporting Information,

Fig. S4(a,b)]. Type 2 alkyl triazole-plasticizers 12a–c give

lower glass transition temperatures compared to their Type

in traditional PVC blends (ΔT DEHP). Typical values for EΔT

g

range from 0 to 100; however, negative values indicate anti-

plasticization, while values above 100 belong to internal plas-

ticizers more efﬁcient than DEHP. EΔT_gvalues grouped by

mole percent and Type are illustrated in Figure 4 (exact EΔT_g

and T_gvalues of all internally plasticized PVC samples are

given in the Supporting Information Table S1, Table S2).

1

7a–c and Type 0D 3a–c analogs. At 15 mol %, 12c (PVC-

TRZ-DiHexyl-TRZ-DiEH) displays the only sub-zero

T

g

1

2

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For Type 0D methyl esters 3a, negative efﬁciency values are

observed at both percentages of substitution, corresponding

to anti-plasticization. Long or branched chains are necessary

to obtain lower glass transition temperatures. This is apparent

in Type 0D 3c containing 2-ethylhexyl triazole esters and the

n-butyl congener 3b. Type 0D triazoles 3d–f possessing PEO

chains exhibit signiﬁcant improvements. Longer PEO chains

enhance plasticization efﬁcacy, which is further ampliﬁed with

higher mole percentages of covalently bound emollient.

Type 1 internal plasticizers containing a single hexyl tether with

alkyl triazole esters generally demonstrated enhanced plasticiza-

tion capabilities over the Type 0D relatives (Fig. 4). This is likely

due to the space created between PVC and the secondary tria-

zole, maximizing the mobility of the plasticizer in the polymeric

matrix. Derivative 7c incorporating the hexyl tether and

2-ethylhexyl triazole esters exhibited the highest efﬁciency

values compared to the Type 1 n-butyl 7b and methyl 7a rela-

tives. In addition, 7c displays an improvement in plasticization

efﬁciency over its Type 0D predecessor 3c, notably at 15 mol %.

The anti-plasticization effect of the rigid primary triazole directly

on PVC is compensated by the addition of the ﬂexible hexyl

tether. Efﬁciencies of Type 1 PEO triazole-plasticizers 7d,e at

15 mol % exceed that of 2-ethylhexyl (2-EH) 7c.

Type 2 triazole-plasticizers exhibit superior EΔT

g

values com-

pared to the Type 1 system (Fig. 4). Extended branching and

longer alkyl chains in both the primary and secondary tria-

zoles are imperative for improved plasticizing efﬁciency when

utilizing alkyl esters. For PEO esters, architectural branching

FIGURE 4 (a) Efﬁciency values (EΔT

g

) of 5 mol % triazole

does not always confer lower T

g

values. For example, 15 mol %

g

internal plasticizers. (b) Efﬁciency values (EΔT ) of 15 mol %

triazole internal plasticizers.

Type 2 12d (PVC-TRZ-DiHexyl-TRZ-DiPEO164Me) contains the

same weight percentage of plasticizer as Type 0D PEO 3f

and EΔT = 42.6. In contrast, at 15 mol %, 14a and 14b give

g

ꢀ

(

PVC-TRZ-DiPEO₅₅₀Me), yet gives a T of −17 C, compared to

g

nearly identical EΔT values.

g

ꢀ

3

f with a T of −29 C. Type 0M PEO samples 14a,b exhibit

g

the two best EΔT values [Fig. 4(b)]. At 15 mol % of cova-

g

lently bound plasticizer, factors such as branching and sec-

ondary triazole spacing become less important than the use of

long PEO chains.

Thermogravimetric Analysis

Thermogravimetric analysis (TGA) and derivative thermogravi-

metry (DTG) were measured to quantitatively determine degra-

dation properties (details in Supporting Information, Tables S3–

S7). DTG of unmodiﬁed PVC reveals two peaks, indicative of a

The highest overall EΔT values at 5 mol % plasticizer belong

g

to Type 2 PEO 12d, Type 0D PEO 3f, and Type 0M PEO 14b

multistage decomposition process with an initial decrease in

ꢀ

[

Fig. 4(a)]. A signiﬁcant increase in plasticizer efﬁciency is

mass at the ﬁrst derivative peak (T

loss (T_d_,_P_V_C₂) at 442 C when measured in air. T

) of 289 C and a second

d,PVC1

ꢀ

noted amongst these top three polymers compared to the next

most efﬁcient samples: Type 2 alkyl 12b,c. These alkyl emol-

lients possess the same three triazole branch points as 12d,

with the only critical difference being the composition of the

secondary triazole ester chains. This illustrates the necessity

of multiple branch points and the incorporation of long PEO

segments for maximal internal plasticizer efﬁcacy, particularly

at low mole percentages.

signiﬁes

d,PVC1

the dehydrochlorination of PVC with concomitant loss of hydro-

chloric acid, formation of various cyclic aromatic compounds,

62

and vinyl chloride. T_d_,_P_V_C₂is indicative of the loss of higher

molecular weight hydrocarbon fragments due to chain scission

of the carbonaceous backbone.

DTG events of internally plasticized samples occurring at

ꢀ

~

430 C are indicative of triazole hydrolysis to alcohol and

Due to the reduced amount of anchoring points at 5 mol %,

aspects such as branching, spacing, and miscibility have an

carboxylic acid. Interestingly, methyl triazoles cause a notable

decrease in T_d_,_P_V_C₁, particularly at 15 mol %. This may stem

from the relative ease of methyl ester hydrolysis, compared to

congeners with larger alkyl esters, which exhibit progressively

elevated T_d_,_P_V_C₁temperatures as the size of the carbon chain

increases (Supporting Information, Tables S4–S6). Broad DTG

augmented effect on EΔT compared to the 15 mol % analogs.

g

A large disparity in T

mol % plasticizer was observed: T

with concomitant plasticizer efﬁciency values of EΔT

g

values for Type 0M 14a and 14b at

ꢀ

5

g

= 65 C versus T

g

= 22 C,

= 13.9

g

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lowering T

g

values. Attachment of two hexyl tethered second-

ary triazoles (Type 2) follows this trend by enforcing another

branch point and increasing molecular weight. Utilization of

PEO esters in all architectural Types signiﬁcantly enhances T

g

depressions, with longer PEO chains exhibiting remarkable

results. It will be interesting to evaluate if unmodiﬁed PVC

can be blended with these PEO functionalized polymers to

ﬁne tune the desired plasticity of the material. Single PEO

ester triazoles (Type 0M) easily prepared from propiolic

esters using low-cost, commercially available materials com-

bine excellent plasticization with straightforward synthesis,

making these nonmigratory internal plasticizers potentially

attractive for industrial applications.

ACKNOWLEDGMENT

The authors gratefully acknowledge research funding from

the National Science Foundation (DMR-1404550).

FIGURE 5 Degree of plasticizer migration of DEHP-PVC blend

and PVC internally plasticized by triazole-phthalate mimics.

REFERENCES AND NOTES

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JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2018

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Article Doi

Nonmigratory internal plasticization of poly(vinyl chloride) via pendant triazoles bearing alkyl or polyether esters

DOI: 10.1002/pola.29205

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Full text of DOI:10.1002/pola.29205

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