Temperature sensitive supramolecular self assembly of per-6-PEO-β-cyclodextrin and α,ω-di-(adamantylethyl)poly(N-isopropylacrylamide) in water

Article abstract of DOI:10.1039/c5sm01293g

The host/guest interactions in water of a star polymer consisting of a β-cyclodextrin (β-CD) core bearing six poly(ethylene oxide) arms linked to the C₆ positions of β-CD (β-CD-PEO₇, M_n 5000 g mol^-1) and α,ω-di-(adamantylethyl)poly(N-isopropylacrylamide) (Ad-PNIPAM-12K, M_n 12 000 g mol^-1) were studied by 1D and 2D ¹H and ¹³C NMR spectroscopy, isothermal calorimetry (ITC), and light scattering (LS). In cold water (T < 26°C) supramolecular "dumbbell" assemblies, consisting of PNIPAM chains with β-CD/Ad inclusion complexes at each end, formed via β-CD-insertion of the terminal Ads through the β-CD secondary face. Light scattering, microcalorimetry (DSC), and DOSY NMR studies indicated that mixed aqueous solutions of β-CD-PEO₇ and Ad-PNIPAM-12K undergo a reversible heat-induced phase transition at ～32°C, accompanied by a release of a fraction of the Ad-bound β-CD-PEO₇ into bulk solution and the formation of aggregated Ad-PNIPAM-12K stabilized by a β-CD-PEO₇ shell.

Full text of DOI:10.1039/c5sm01293g

View Article Online
View Journal
Soft Matter
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: V. Bennevault, C.
Huin, P. Guegan, E. Korchagiva, X. Qiu and F. M. Winnik, Soft Matter, 2015, DOI: 10.1039/C5SM01293G.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/softmatter

Page 1 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
Temperature Sensitive Supramolecular Self Assembly of per-6-PEO-β-
cyclodextrin and α,ω-Di-(adamantylethyl)poly(N-isopropylacrylamide) in Water
abc
V. Bennevault , C. Huin , P. Guégan , E. V. Korchagina , X.-P. Qiu and F. M.
d
bc*
e
e
efg*
Winnik
a
Université d'Evry Val d'Essonne, 91025 Evry Cedex, France
b
Sorbonne Universités, UPMC Université Paris 06, UMR8232, IPCM, Chimie des
Polymères, 75005 Paris, France
c
CNRS, UMR8232, IPCM, Chimie des Polymères, 75005 Paris, France
d
Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement,
UMR8587 UEVE-CNRS-CEA, 91025 Evry Cedex, France
e
Department of Chemistry and Faculty of Pharmacy, University of Montreal, CP
6
128 Succursale Centre Ville, Montreal, QC, H3C3J7, Canada
f
WPI International Center for Materials Nanoarchitectonics (MANA), National
Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 Japan
g
Department of Chemistry and Faculty of Pharmacy, University of Helsinki, Helsinki
FI 00014
Abstract
The host/guest interactions in water of a star polymer consisting of a β-cyclodextrin
(
β-CD) core bearing six poly(polyethylene oxide) arms linked to the C positions of
6
-
1
β-CD (β-CD-PEO
7
, M
n
5,000 g.mol ) and α,ω-di-(adamantylethyl)poly(N-
-1
n
isopropylacrylamide (Ad-PNIPAM-12K, M 12,000 g.mol ) were studied by 1D and
1 13
D H and C NMR spectroscopy, isothermal calorimetry (ITC), and light scattering
2
o
LS). In cold water (T < 26 C) supramolecular “dumbbell” assemblies, consisting of
(
1

Soft Matter
Page 2 of 37
View Article Online
DOI: 10.1039/C5SM01293G
PNIPAM chains with β-CD/Ad inclusion complexes at each end, formed via β-CD-
insertion of the terminal Ads through the β-CDs secondary face. Light scattering,
microcalorimetry (DSC), and DOSY NMR studies indicated that mixed aqueous
solutions of β-CD-PEO and Ad-PNIPAM-12 undergo a reversible heat-induced
7
o
phase transition at ~ 32 C, accompanied by a release of a fraction of the Ad-bound β-
CD-PEO
7
into bulk solution and the formation of aggregated Ad-PNIPAM-12K
shell.
stabilized by a β-CD-PEO
7
1
. Introduction
The creation of polymeric supramolecular assemblies is a fertile field of current
1
research, generating a realm of structures, such as polymeric micelles ,
,2
3
polymersomes , polyrotaxanes , hydrogels , nanotubes
4,5
6,7
8,9,10
. Applications in drug
1
1
12
delivery , nanoreactors , or nanopores, to name but a few,
13,14
have been reported
and opened new areas for materials development. Formation of reversible assemblies
15,16 17,18
, metal coordination , arene-
has been achieved through hydrogen bonding
1
9
20
21
arene (π-π), ionic, and hydrophobic interactions . Cyclodextrins-based inclusion
complexes are used often to construct functional supramolecular assemblies through
2
hydrophobic interactions . Cyclodextrins are cyclic oligosaccharides consisting of 6,
2
7
, or 8 glucopyranose units linked by 1,4-α-glycosidic bonds named, respectively, α,
β, or γ-CD. They have a truncated conical shape with a hydrophilic outer part and a
hydrophobic cavity that enables the formation of host-guest inclusion complexes that
can be dissociated by application of stimuli, such as heat, addition of competitive
guests or dilution.
The development of well-defined functional polymers bearing CD units, such as star
2
3,24,25 26,27
, linear polymers end-capped by CD unit(s) , or polymers with CD
polymers
2

Page 3 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
28
29
pendant groups, has lead to a library of new supramolecular architectures with
reversible topology through host/guest chemistry. Polymeric building blocks AB
2
with one adamantyl and two CD moieties at the chain ends led to the formation of
3
hyperbranched polymers , while CD-based star polymers led to the formation of
0
3
1,32
23,33
34
mikto-star , dumbbell
groups were used to generate comb polymers
Polymers end-capped with CD were employed to form block copolymers
and H-shaped copolymers. Polymers with CD pendant
2
8,35
36,37
and reversible networks
.
26,38
and
3
cyclic polymers . The use of responsive polymers to construct the supramolecular
9
structures offers new opportunities to design multi-stimulable materials as intelligent
4
0
38,41 42
, magnetic field ,
switches. The stimuli commonly used include pH , light
4
chemical and temperature
3
23,36
. Temperature-sensitive assemblies take advantage of
polymer/water systems that exhibit a lower critical solution temperature (LCST) in
their phase diagram.
Poly(N-isopropylacrylamide) (PNIPAM) is very soluble in cold water up to a
o
temperature around 32 C. At this temperature aqueous PNIPAM solutions undergo a
phase transition observed macroscopically by a change of the solution appearance
from clear to turbid. The phase transition is a consequence of the dehydration,
collapse, and aggregation of PNIPAM chains. This process is accompanied by release
of bound water into bulk, which is detected by an endotherm (ꢀH ~ 1.4 kcal/NIPAM
o
44
unit) with a maximum T
m
~ 32 C. This temperature may be raised or lowered via
introduction of hydrophobic/hydrophilic groups along the chain or on the chain
26
ends . Tunability of the LCST of PNIPAM is well documented and various
4
5,46,47
strategies were reported to tune the LCST of PNIPAM between 26 and 34°C
.
Heating an aqueous solution of PNIPAM leads to the formation of rigid
mesoglobules, with a hydrodynamic radius of 50 to 200 nm, that resists macroscopic
3

Soft Matter
Page 4 of 37
View Article Online
DOI: 10.1039/C5SM01293G
48
phase separation . The control of the mesoglobule size is achieved by control of
4
9
physicochemical conditions, such as heating rate and polymer concentration . To the
best of our knowledge, reduction of the mesoglobule size through chemical
modification has not been reported yet.
We report here the construction of supramolecular structures formed by interaction of
CD-based star polymers and α,ω-di(adamantylethyl)-PNIPAM in aqueous solution.
The star polymer was synthesized by “click” ligation of linear α-methoxy-ω-
propargylpolyethylene oxide to per-6-deoxy-6-azido-β-cyclodextrin. The α,ω-
di(adamantylethyl)-PNIPAM was synthesized by end-modification of α,ω-dithiol-
PNIPAM obtained by RAFT polymerization of NIPAM. Supramolecular assemblies
of the two polymers were constructed in aqueous solution and studied as a function of
temperature and concentration by isothermal titration calorimetry (ITC), differential
scanning calorimetry (DSC), dynamic and static light scattering (DLS and SLS), and
multinuclei NMR spectroscopy. Remarkably the assemblies, which are stable at room
temperature, underwent dynamic release/reinsertion of the β-CD-PEO /Ad-PNIPAM
7
o
motif as a result of heating and cooling, respectively, within the 25 C to 50 C
o
temperature range.
2
. Experimental Section
2
.1 Materials. All chemicals were purchased from Sigma-Aldrich chemicals Co.
unless otherwise specified. Azobisisobutyronitrile (AIBN, 98%) was recrystallized
from methanol prior to use. N-Isopropylacrylamide (NIPAM, 99%) was obtained
from Acros Organics and recrystallized from an acetone/hexane (4/6, v/v) mixture. 1-
Adamantaneethanol (98%), methanesulfonyl chloride (99%), sodium azide (99.5%),
triphenylphosphine (98.5%), tetrabromomethane (99%), hydrated copper sulfate
4

Page 5 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
(99%, Fluka), sodium ascorbate (99%, Fluka) and ammonium hydroxide solution
(5M, Fluka) were used as received. Propargyl bromide was received in solution
(80 wt. % in toluene) and was used without further purification. The β-cyclodextrin
(98%) was purified before use. An aqueous saturated solution of β-CD was prepared
at 80°C, then slowly cooled down to room temperature and let at 0°C for one night.
The crystallized β-CD was then filtered and dried under vacuum at 80°C over one
night. α-Methoxypolyethylene oxide was purchased from Acros Organics. 1,4-
Dioxane, N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) were purified
by a solvent purification system with two packed columns of activated alumina
provided by Innovative Technology Inc. All other solvents were of reagent grade and
used as received. Water was deionized using a Millipore MilliQ system.
2
1
1
.2 Synthesis of adamantane derivatives and polymers
-Adamantaneethyl Iodide
-Adamantaneethanol (1.8 g, 10 mmol) and methanesulfonyl chloride (1.7 g, 15
mmol) were dissolved in 20 mL of THF. A solution of triethylamine (1.5 g, 15 mmol)
in THF (5.0 mL) was added dropwise to the stirred solution cooled in an ice-bath. At
the end of the addition, the reaction solution was allowed to warm to room
temperature and stirred for 5 hours. Subsequently, the solvent was removed by rotary
evaporation under vacuum. The remaining light yellow liquid was dissolved in
2 2
CH Cl (5.0 mL), washed in sequence with aqueous HCl (0.5 M) solution, saturated
NaHCO solution, brine, and water. The organic phase was separated and dried over
3
anhydrous Na SO overnight. CH Cl was removed by rotary evaporation. The
2
4
2
2
remaining light yellow liquid was dissolved in acetone (40 mL). Sodium iodide (7.5 g,
0 mmol) was added to the solution. The mixture was stirred in the dark under N
5
2
5

Soft Matter
Page 6 of 37
View Article Online
DOI: 10.1039/C5SM01293G
atmosphere at room temperature for 2 days. Subsequently, the insoluble salt was
removed by filtration. The solvent was evaporated in vacuum. The remaining solid
was dissolved in a small amount of CH
2
Cl
2
and purified by flash chromatography of
1
silica gel using CH Cl /hexane (1:1 v:v) as eluent. Yield 2.2 g, 76%. H NMR
2
2
(
CDCl
CH -CH-CH
CH-), 3.18-3.22 (m, 2H, I-CH
3
) ppm, δ 1.52 (d, 6H, adamantane C-CH
-), 1.80-1.84 (m, 2H, I-CH -CH -), 1.98 (s, 3H, adamantane C-CH
-CH -) (Figure S1).
2
-), 1.60-1.70 (q, 6H, adamantane C-
2
2
2
2
2
-
2
2
α, ω-Di(adamantine)ethyl poly(N-isopropylacrylamide) (Ad-PNIPAM-12K,
Scheme 1)
The precursor polymer, α,ω-dithiol poly(N-isopropylacrylamide) ( Mn = 12,000 g/mol,
as determined by GPC using DMF as eluent) was prepared by RAFT polymerization
using diethylene glycol di(2-(1-isobutyl)sulfanylthiocarbonylsulfanyl-2-methyl
propionate) as the chain transfer agent and subsequent aminolysis to convert the 2-(1-
5
isobutyl)sulfanylthiocarbonylsulfanyl into thiol, as reported previously. The reaction
0
of α,ω-dithiol poly(N-isopropylacrylamide) with 1-adamantaneethyl iodide was
51
carried out according to a previously reported procedure . Briefly, α,ω-dithiol
poly(N-isopropylacrylamide) (0.60 g, 0.05 mmol) and 1-adamantaneethyl iodide (44.0
mg, 0.150 mmol) were dissolved in 5 – 10 mL of DMF. A catalytic amount of the
reducing agent triphenylphosphine was added to prevent the formation of disulfide
bonds during reaction. The reaction mixture was stirred at room temperature under N
2
atmosphere overnight. The product was recovered by precipitation into diethyl ether
and purified by two consecutive precipitations from THF into diethyl ether.
1
H NMR (CDCl
3
) ppm, δ 1.02 (d, -CH
2 3 2 3 2
C(CH ) ), 1.16 (s, -NHCH(CH ) ), 1.20-2.40
(multiplet, polymer backbone protons), 1.50 (s, C-CH - (adamantane)), 1.60-1.70 (s,
2
6

Page 7 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
C-CH
.66 (s, -OCH
Figure S2).
2
-CH-CH
2
- (adamantane)), 1.98 (s, C-CH
2
-CH- (adamantane)), 3.28 (s, -SCH
2
),
3
2
), 4.02 (s, -NHCH), 4.22 (s, -C(=O)OCH
2
), 6.40 (bs, -C(=O)NH)
(
Heptakis(6-deoxy-6-azido)β-CD (β-CD-N
Sodium azide (6.81g, 88 mmol) was added to a solution of β-cyclodextrin (1.0 g, 0.88
mmol) in dry DMF (90 mL). The resulting suspension was stirred at 80 °C under N
for 2 hr. The reaction mixture was cooled to room temperature and treated with PPh3
3
)
2
(6.91 g, 26.4 mmol). A freshly prepared solution of CBr (8.76 g, 26.4 mmol) in DMF
4
(10 mL) was rapidly added to the mixture. The orange-yellow solution was stirred at
2
room temperature under N for 48 hr. Methanol (5 mL) was added to quench the
reaction. The product was precipitated by addition of ethanol (300 mL). It was
separated by filtration and washed with ethanol followed by a 7:3 ethanol/water
solution. The product was dried at 60 °C under high vacuum to yield a white powder
5
1.03 g, 90%) .
2
(
1
H NMR (DMSO-d6) ppm, δ:3.20 – 3.52 (m, 21H), 3.52 – 3.71 (m, 14H), 3.71 – 3.98
(
(
(
m, 14H), 4.95 (d, J = 3 Hz, 7H), 5.81 (d, J = 2 Hz, 7H), 5.96 (d, J = 7 Hz, 7H)
13
Figure S3). C NMR (DMSO-d6) ppm, δ: 52.33, 71.34, 73.00, 73.59, 84.20, 103.05
-1
-1
Figure S4). IR spectrum : νOH= 3356 cm , νN3= 2104 cm (Figure S5).
-1
α-Methoxy-ω-propargyl poly(ethylene oxide) ( Mn = 550 g.mol )
A solution of propargyl bromide (80 wt. % in toluene) in excess was added dropwise
to a mixture of α-methoxy polyethylene oxide (10 g, 18 mmol) and sodium hydroxide
(1.44 g 36 mmol). The solution was stirred at 65 °C for 24 hr under N
2
. It was cooled
to room temperature and the solvent was evaporated. CH Cl (100 mL) was added to
2
2
the residue. The solution was washed with water (3 × 50 mL) until the pH of the
7

Soft Matter
Page 8 of 37
View Article Online
DOI: 10.1039/C5SM01293G
aqueous phase became neutral. The organic layer was retained and evaporated. The
1
product obtained was dried under vacuum. H NMR (CDCl3) ppm, δ: 2,51 (s, 1H),
1
,32 (s, 3H), 3,85 (m, 47H) 3,91 (s, 2H) (Figure S6); C NMR (CDCl
3
3
3
) ppm, δ:
5
7.03, 58.22, 63.22, 71.32, 72.32.
Heptakis[6-deoxy-6-(1,2,3-triazole-ω-methoxy poly(ethylene oxide)]-β-
cyclodextrin (Scheme 2) (β-CD-PEO -5K)
7
Heptakis(6-deoxy-6-azido)β-CD (0.52 mmol) and hydrated copper sulfate (4.00
mmol) wee added to a solution of α-methoxy-ω-propargyl polyethylene oxide (4.00
mmol) in DMSO (20 mL). A freshly prepared solution of sodium ascorbate (8.2
mmol) in water was added dropwise to the solution and the resulting solution was
stirred for 48 hr at room temperature. The crude product obtained after evaporation of
the solvent was dissolved in CH Cl . The solution was treated with an ammonium
2
2
4
hydroxide solution (NH OH, 5M) overnight before purification by a small silica gel
53
column. The solvent was removed and the desired product was dried under vacuum .
1
H NMR (
D
2
O) ppm, δ: 3.39 (s, 21H), 3.42 (m, 7H), 3.64 (m, 7H), 3.71 (m, 308H),
3
8
1
.95 (m,7H), 4.16 (m, 7H), 4.29 (m,7H), 4.42 (m, 7H), 4.48 (m,14H), 5.18 (d, 7H),
13
.05 (s, 7H) (Figure 1); C NMR (DMSO) ppm, δ: 51.20, 59.69, 64.76, 71.36, 84.29,
03.21, 127.28, 145.37 (Figure S7).
2
.3 Instruments and methods
NMR Spectroscopy
1
H NMR spectra were recorded on a Bruker AMX-400 (400 MHz) instrument and
chemical shifts are referenced to tetramethylsilane (TMS) (PNIPAM and adamantane
1
derivatives) or on a Bruker AV300 spectrometer operating at 300 MHz (all other H
13
NMR (1-D), C NMR spectra and DOSY experiments). For DOSY NMR
8

Page 9 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
measurements, the maximum field gradient strength (56.8 G/cm) was calibrated using
a homemade Plexiglas phantom inserted in a H O filled NMR tube and using the
pulse program calibgp. The accuracy of the calibration was checked by measuring the
2
5
self-diffusion coefficient of a H O/D O mixture (10 %/90 % in moles) at 25 °C .
4
2
2
The DOSY experiments were carried out using the stegp1s pulse sequence with a
linear gradient of 16 steps between 2% and 95%. The mathematical treatment of the
55
data was performed as were previously described . The COSY, TOCSY, NOESY
and HSQC experiments were performed on an Avance 600 MHz Bruker instrument.
The temperature of the samples was controlled during all measurements. Temperature
calibration between 298 K and 313 K was performed with a sample of 100% CH OH.
3
Chemical shifts were referenced against an external reference containing 3-
(trimethylsilyl)propionic-2,2,3,3-d4 acid sodium salt.
Gel permeation chromatography
Gel permeation chromatography (GPC) was performed with a system consisting of an
Agilent 1100 isocratic pump, a set of TSK-gel α-M (particle size 13 ꢁ, exclusion limit
7
1
×10 Da for polystyrene in DMF) and a TSK-gel α-3000 (particle size 7 ꢁ, exclusion
5
limit 1×10 Da for polystyrene in DMF) (Tosoh Biosep) columns, a Dawn EOS multi-
angle laser light scattering detector λ = 690 nm (Wyatt Technology Co.) and an
Optilab DSP interferometric refractometer λ = 690 nm (Wyatt Technology Co.)
under the following conditions: injection volume, 100 ꢁL; flow rate, 0.5 mL/min;
eluent, DMF; temperature, 40 °C. The dn/dc value of PNIPAM was determined to be
0
.0738 mL/g at 690 nm in DMF at 40 °C using an Optilab DSP interferometric
refractometer (Wyatt Technology Corp).
High-Sensitivity Differential Scanning Calorimetry (HS-DSC).
9

Soft Matter
Page 10 of 37
View Article Online
DOI: 10.1039/C5SM01293G
HS-DSC measurements were performed on a VP-DSC microcalorimeter (MicroCal
Inc.) for which the cell volume was 0.52 mL and the external pressure was ca. 180
kPa. The heating rate was 1.0 °C/min in the temperature scans ranged from 10 to 70
°
C. The experimental data were analyzed using the Origin-based software supplied by
the manufacturer. The polymers were dissolved in water at a concentration of 1.0 g/L.
The temperature of the phase transition (T ) was taken at the maximum of the
m
endotherm. For each experiment, three heating and cooling scans were recorded
consecutively.
Isothermal Titration Calorimetry (ITC)
Isothermal titrations were performed with a MicroCal VP-ITC microcalorimeter
equipped with a 1.43 mL sample cell and a 300 ꢁL syringe. For cmc measurements, a
8
.0 g/L solution of Ad-PNIPAM-12K was titrated into water in 56 aliquots (5 ꢁL
each). For the study of inclusion complex between Ad-PNIPAM-12K and β-CD/β-
CD-PEO , β-CD/β-CD-PEO solutions were loaded in the syringe and injected into
7
7
the cell in 28 aliquots (10 ꢁL each) at an interval of 300 seconds. The cell temperature
was set at 20 °C in all experiments. An aqueous solution of unmodified PNIPAM was
used as a blank in control experiments. The experimental data were analyzed using
the Origin-based software supplied by the manufacturer.
Static and Dynamic Light Scattering Measurements (SLS and DLS)
Light scattering experiments were performed on an ALV GmbH instrument equipped
with a CGS-3 goniometer and an ALV-5000 multiple digital time correlator. A He-Ne
laser operating at a wavelength of λ = 632.8 nm was used as the light source. All
0
solvents and solutions were filtered through 0.22 µm pore size filter directly into the
1
0 mm sample cells. DLS measurements were done at a scattering angle θ = 90°. The
Hydrodynamic radii distribution was obtained by analysis of the correlation function
1
0

Page 11 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
using the ALV software provided by manufacturer. For critical aggregation
concentration (cac) determination, aliquots of a solution of Ad-PNIPAM-12K in
water (8.0 g/L) was added stepwise into a specified amount of water placed in the
sample cell to prepare solutions of increasing polymer concentration. Scattering
intensities were determined at right angle and plotted against polymer concentration.
The cac was determined as the crossing of the linear fits of intensities before and after
the increase in scattering intensity that signals the onset of interpolymeric assembly.
For DLS and SLS studies performed with solutions heated above the phase transition
temperature, polymer solutions of low concentration (0.02 g/L) were used. They
remained clear to the eye when heated above the polymer cloud point. Solutions were
kept at 52 °C for at least 1 hr prior to measurements. The scattering angle varied from
3
0 to 150°. In DLS experiments relaxation time was registered at each angle. The
diffusion coefficient was obtained from a plot of the relaxation rate (reciprocal
4π n
λ0
2
relaxation time) vs the square of the scattering vector q ( q =
⋅sin(θ
/ 2) ), n-
refractive index of water. The hydrodynamic radius was calculated using Stokes-
55
Einstein equation . In SLS experiments, the angular dependence of the excess
absolute time-average scattered intensity with respect to the solvent (Rayleigh ratio R)
2
was measured. Parabolic approximation of the plot R (q ) was used to obtain radius of
gyration Rg.
Temperature dependent measurements were done with 1 g/L solutions of Ad-
PNIPAM-12K (1.0 g/L) without and with a 2 fold molar excess of β-CD or β-CD-
PEO
5 to 50 °C, and back, with the approximate heating/cooling rate of 0.3 °C/min. Data
were collected at 90 °.
7
versus adamantane (r = [β-CD]/[Ad] = 2). The temperature was increased from
1
1
1

Soft Matter
Page 12 of 37
View Article Online
DOI: 10.1039/C5SM01293G
3
. Results
3
.1 Preparation and characterisation of the polymers.
The polymer β-CD-PEO (Scheme 2) was obtained by reaction of propargyl groups
linked to one end of polyethylene oxide (PEO) chains with azide groups linked to the
7
53
seven primary carbons of β-CD, as described in detail in a previous publication . The
Huisgen [2+3] cycloaddition between α-methoxy-ω-propargyl-PEO, synthesized by a
phase transfer catalysed reaction of propargyl bromide with the ω-hydroxyl group of
57
α-methoxy-ω-hydroxy-PEO, and heptakis(6-deoxy-6-azido)-β-CD was performed
in DMSO using 1.1 equivalents, with respect to the azide functions, of both
CuSO
4
2
.xH O and α-methoxy-ω-propargyl-PEO, in order to ensure that a PEO chain
is linked to all the azide moieties of β-CD-N
3
. The use of a polar solvent, either DMF
II
or DMSO, significantly reduces the undesired association of Cu ions with the CD
secondary face that takes place in non-polar solvents.
The success of the coupling of PEO chains to the cyclodextrin ring was confirmed by
the presence of a singlet around 8.05 ppm, assigned to the triazole proton (H7), in the
1
7 2
H NMR spectrum of β-CD-PEO in D O (Figure 1). This spectrum also presents
signals due to the cyclodextrin ring protons (from ~ 3.3 to 5.3 ppm), a singlet at 3.39
ppm assigned to the terminal methoxy group of the PEO chains, and a strong signal at
3
.71 ppm due to the methylene protons of the PEO chains. The HSQC spectrum of β-
CD-PEO (Figure 2a) allows the assignments of the signals at 4.29 ppm and 4.42 ppm
7
to the non-equivalent protons H6 and H6’, respectively. Similarly, the signal at 4.48
ppm is readily assigned to the proton H8. Complete assignment of the signals in the
1
7
H NMR spectrum of β-CD-PEO was achieved via COSY and NOESY experiments.
The COSY spectrum, presented in Figure 2b, allows assignment of the signals due to
1
2

Page 13 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
the protons H1 to H5 of cyclodextrin, as follows: H1 (5.18 ppm), H2 (3.63 ppm), H3
4.01 ppm), H4 (3.43 ppm) and H5 (4.27 ppm). A TOCSY experiment was carried out
(
in order to confirm the assignments of all CD protons (Figure S8). The NOESY
spectrum (Figure 3) shows that the triazole proton (H7) is correlated via a negative
cross-peak to H1, H2, H3, H4, H5, H6, H6’and H8. We confirmed that the
assignments obtained via 2D NMR spectroscopy agree well with the integration of the
signals in the 1D NMR spectrum of β-CD-PEO
7
.
α,ω-Di-(adamantylethyl)-poly(N-isopropylacrylamide)
(Ad-PNIPAM-12K)
was
prepared by nucleophilic substitution of the mercaptan functions linked to each end of
the PNIPAM chains with iodoethyladamantane (Scheme 1), following a procedure
reported earlier for the preparation of α,ω-dipyrenyl- and α,ω-dicholesteryl-
5
PNIPAM . The level of functionalization, assessed by the Ellman test for residual
0
5
8
1
thiols was greater than 90 %. The H NMR spectrum of Ad-PNIPAM-12K in CDCl
Figure S2), displayed signals characteristic of PNIPAM, as well as signals at 1.50
and 1.98 ppm ascribed, respectively, to the resonances of the protons -C-CH - and -C-
3
(
2
CH
.2 Properties of β-CD-PEO
PEO readily dissolves in water at all temperatures within the range of interest in this
2
-CH- of the adamantyl end groups.
3
7
and Ad-PNIPAM-12K in water. The polymer β-CD-
7
o
study (~ 5 C to ~ 80 C), up to a concentration of ~ 22 g/L. Above this concentration,
o
intermolecular association of β-CD-PEO occurs. Ad-PNIPAM-12K is soluble in cold
7
-
5
water. When the polymer concentration exceeds ~ 0.25 g/L or ~ [Ad] ~４×10 mol/L,
the chains aggregate as seen by an increase in the intensity of the light scattered by
the solution (Figure 4a), DLS studies indicate that nanoparticles of hydrodynamic
h
radius R ~30 nm coexist with Ad-PNIPAM-12K unimers, (Figure 5a, black squares).
The concentration range over which aggregation takes place was determined also by
1
3

Soft Matter
Page 14 of 37
View Article Online
DOI: 10.1039/C5SM01293G
isothermal titration calorimetry (ITC) which monitors the heat exchange upon
titration of an aqueous solution of Ad-PNIPAM-12K (8.0 g/L) into water (Figure 4b).
Aqueous solutions of Ad-PNIPAM-12K undergo a phase transition upon heating. The
o
transition temperature recorded by HS-DSC (Figure S9) is T = 27.4 C. This
m
temperature is lower than the value recorded in the case of the unmodified PNIPAM
5
9
sample of identical molar mass (33.5 °C) . The decrease of the phase transition
temperature upon end-modification of PNIPAM with adamantylethyl groups can be
attributed to the hydrophobic nature of the adamantylethyl end-groups, as reported in
6
the case of other alkyl or aryl-end modified PNIPAMs .
0
3
7
.3 Interactions between β-CD-PEO and Ad-PNIPAM-12K in water below the
phase transition temperature of Ad-PNIPAM-12K.
Simple visual observation of Ad-PNIPAM-12K solutions before and after addition of
β-CD suggests that the end-groups of Ad-PNIPAM-12K are able to form inclusion
complexes with β-CD. In the top right section of Figure 5, we present photographs of
o
vials kept at room temperature (20 C) containing an aqueous solution of Ad-
-1
PNIPAM-12K (5 g.L ) alone (left) and in the presence of either β-CD (middle) or β-
CD-PEO (right) with [Ad]:[β-CD]=1:2 in both cases ([Ad] and [β-CD] represent
7
respectively the concentration of adamantyl and β-CD groups). The Ad-PNIPAM-
1
2K solution is slightly turbid, due to the formation of Ad-PNIPAM-12K aggregates.
Upon addition of β-CD or β-CD-PEO in an amount such that [Ad]:[β-CD]=1:2, the
solution becomes clear, which can be taken as an indication that the Ad-PNIPAM-
2K aggregates are destroyed by β-CD or β-CD-PEO7. Inclusion of Ad into the
hydrophilic β-CD presumably increases the solubility of Ad-PNIPAM-12K in water.
7
1
1
4

Page 15 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
Isothermal Titration Calorimetry (ITC)
Isothermal titrations were carried out by adding solutions of β-CD (3.6 mmol) or β-
CD-PEO
(4.0 mmol of β-CD) to an Ad-PNIPAM-12K solution (0.33 mmol of Ad).
Titrations of β-CD and β-CD-PEO into PNIPAM were carried out under the same
7
7
conditions (Figure S10). The resulting enthalpograms were subtracted from the
corresponding titrations of Ad-PNIPAM-12K in order to remove heat effects
associated with the dilution of β-CD and β-CD-PEO
7
and possible interactions of the
titrants with the PNIPAM backbone. Figure 5c depicts the enthalpogram of β-CD into
Ad-PNIPAM-12K. The curve was fitted to a one binding site model that led to a ~
5
-1
1
:1 Ad/β-CD ratio and an association constant of 1.3 x 10 L.mol , a value typical
35,61
for the association between adamantyl derivatives and β-CD . The enthalpogram
corresponding to the titration of β-CD-PEO
7
into Ad-PNIPAM-12K is presented in
4
Figure 5d. A fit to a one-binding site model gave a binding constant of 2.4 x10
-
1
L.mol , a value significantly lower than the association between Ad-PNIPAM-12K
and β-CD, in agreement with previous reports on the binding of adamantyl
3
5,61
derivatives to polymer-bound β-CD
.
Dynamic light scattering measurements
Having established the formation of inclusion complexes between the end-groups of
Ad-PNIPAM-12K (guests) and β-CD-PEO7, we set about to assess the consequences
of the complexation on the solution properties of Ad-PNIPAM-12K. DLS
measurements performed for mixed solutions of Ad-PNIPAM-12K and either β-CD-
PEO or β-CD (Figure 5a) indicated that when the molar ratio r = [CD]/[Ad] is equal
7
to 2, the contribution of Ad-PNIPAM-12K aggregates to the scattering intensity is
significantly reduced and that scattering objects of R ~ 3 nm become predominant.
h
1
5

Soft Matter
Page 16 of 37
View Article Online
DOI: 10.1039/C5SM01293G
The latter are attributed tentatively to isolated Ad-PNIPAM-12K chains carrying β-
CD groups associated to the adamantyl end groups.
1
D and 2D NMR measurements
The stoechiometry of the Ad-PNIPAM-12K/β-CD-PEO complex in mixed systems
7
1
of varying adamantyl to β-CD molar ratio was investigated by H NMR spectroscopy.
-3
-1
Spectra of mixed solutions ([Ad-PNIPAM-12K]=2.50.10
mol.L ; [β-CD-
-
3
-3
-1
]=1.25.10 to 6.25.10 mol.L ) kept at 23°C (r = [CD]/[Ad] ranging from 0.25
PEO
7
to 1.25) were recorded and compared to the spectrum of β-CD-PEO
7
. The changes of
the chemical shift of the signal around 8.0 - 8.1 ppm attributed to the triazole proton
are presented in Figure 6. The chemical shift of the triazole proton remained constant
for 0.25 < r ≤ 1.0. However, in the spectra of solutions with r >1.0, it underwent a
downfield shift, suggesting the formation of 1:1 Ad/CD inclusion complexes. The
chemical shift of the CD anomeric protons at 5.17 ppm underwent a similar shift (data
not shown), while the chemical shifts of the other protons on the CD groups remained
constant for all solutions. These results suggest that all the CD groups form
complexes with Ad as long as CD is the minority component.
A mixed solution of ratio r = 1 was analyzed by 2D NMR spectroscopy. The chemical
shifts of the β-CD-PEO
as follows: H1 (5.17 ppm), H2 (3.64 ppm), H3 (3.95 ppm), H4 (3.42 ppm) and H5
4.16 ppm) based on the TOCSY spectrum of the mixed solution. The signals due to
H3 and H5, which are located inside the CD cavity, underwent an upfield shift
compared to uncomplexed β-CD-PEO [H3 (4.01 ppm); H5 (4.27 ppm)], whereas the
7
protons in the presence of Ad-PNIPAM-12K were assigned
(
7
chemical shifts of the protons H2 and H4 remained identical to those of uncomplexed
β-CD-PEO . This observation confirms that the adamantyl moiety is located within
7
1
6

Page 17 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
the hydrophobic CD cavity. The NOESY NMR spectrum of mixed solution (Figure 7)
exhibited intense correlation peaks between H3 and H5 and the protons linked to the
adamantyl group. The latter signals, which are masked by the signals due to the CH-
1
CO and CH protons of the polymer backbone in the H NMR spectrum of the mixed
2
solution, are readily identified by a negative cross-peak in the 2D spectrum. The
NOESY spectrum gave the following chemical shifts: 1.65 ppm, 1.80 ppm, 1.96 ppm
2
and 2.25 ppm which were assigned to the residue -CH -Ad (Figure 7). Moreover, it
was noted that the intensity of the signals correlation peaks is higher for H3 than H5,
implying that the inclusion of Ad into CD occurred mainly via the CD secondary rim,
58
in agreement with Carrazana et al . The steric hindrance induced by the PEO chains
linked to the primary rim further enhances the preferred entry of CD via the
secondary rim.
Diffusion-ordered spectroscopy (DOSY) NMR experiments, which are based on a
pulse-field gradient spin-echo NMR measurements on mixtures of diffusing
62-65
components
7
were performed as well, using solutions of β-CD-PEO concentration
lower than the polymer cac, with r = 1: [Ad-PNIPAM-12K] = 0.5×[β-CD-PEO ] =
7
-
4
-1
.125×10 mol.L . The diffusion coefficients recorded at 23 C are presented in Table
°
3
1
. In this mixture, Ad-PNIPAM-12K and β-CD-PEO have similar diffusion
7
coefficients, bringing further evidence of the Ad/β-CD complexation linking the two
polymers.
3
.4 Temperature-dependence of the interactions between β-CD-PEO
7
and Ad-
PNIPAM-12K in water
As presented in Figure 8, left, aqueous solutions of Ad-PNIPAM-12K are slightly
turbid at room temperature, whereas mixed solutions of Ad-PNIPAM-12K and either
1
7

Soft Matter
Page 18 of 37
View Article Online
DOI: 10.1039/C5SM01293G
β-CD or β-CD-PEO are clear as a consequence of the β-CD-induced disruption of
7
Ad-PNIPAM-12k aggregates. Solutions of Ad-PNIPAM-12K with or without β-CD
o
became cloudy upon heating to 50 C (Figure 8, right). Upon cooling
or β-CD-PEO
7
to room temperature, the samples recovered their original appearance. This
observation is quite important, since it implies that the major amount of Ad/β-CD
inclusion complexes are broken during the heat treatment, but they form again upon
cooling. The experiments described below were performed in order to get a firmer
description of the response of mixed systems to changes in temperature.
HS-DSC measurements
First, the phase transition of Ad-PNIPAM-12K in mixed aqueous solutions of either
β-CD-PEO or β-CD (r = 1 and r = 2) was examined by HS-DSC measurements. In
7
the presence of β-CD-PEO
maximum (T
) increased from 27.4°C (no added β-CD-PEO
1.1°C (r =2), while in the presence of β-CD the T value shifted from 27.4°C to
7
the temperature corresponding to the endotherm
m
7
) to 30.1°C (r = 1) and
3
3
m
1.9°C (r = 1) and 33.3 °C (r = 2). The corresponding endotherms are presented in
Figure S9 and S11. The enthalpy of the transition was also affected by the presence of
-
1
β-CD-PEO or β-CD. It increased from 1.42 ± 0.10 kcal/mol (Ad-PNIPAM-12K
7
-1
-1
alone) to 1.56 ± 0.12 kcal/mol (r = 1) and 1.67 ± 0.12 kcal/mol (r = 2). In order to
understand the changes in the transition enthalpy, it is important to compare first the
transition enthalpy for solutions of Ad-PNIPAM-12K alone to that of unmodified
-1 59
PNIPAM of similar molar mass (1.58 kcal.mol ) . The decrease of the transition
enthalpy of Ad-PNIPAM-12K, compared to unmodified PNIPAM is a consequence of
the steric constraints imposed by the association of Ad-PNIPAM-12K that prevent
full hydration of the PNIPAM chains in the aggregates, as observed also in the case of
1
8

Page 19 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
5
9
α,ω-di(n-octadecyl)-PNIPAM . The fact that the transition enthalpy in mixed
solutions of r = 2 is nearly identical to that of unmodified PNIPAM, implies that the
hydration of the PNIPAM chain in solutions of cyclodextrin-capped Ad-PNIPAM-
1
2K is similar to that of unmodified PNIPAM. Hence, the increase in the transition
enthalpy of Ad-PNIPAM-12K in the presence of β-CD can be attributed to the
disruption of the Ad-PNIPAM-12K aggregates that exist in cold solutions upon
inclusion of the Ad endgroups into β-CD.
Light scattering measurements
DLS and SLS measurements were carried out for mixed solutions of Ad-PNIPAM-
1
0
9
2K and β-CD or β-CD-PEO of constant r value (r = 2) for polymer concentration c-
7
.02 g/L at 52 °C (Figure 9). The R
), a value typical for hard sphere aggregates, or mesoglobules. In mixed solutions of
(with [Ad-PNIPAM-
shifts to slightly lower values, 0.65 and 0.62 (Figure
), respectively, usually attributed to aggregates of core/shell structures. This
g h
/R ratios of Ad-PNIPAM-12K was 0.75 (Figure
Ad-PNIPAM-12K/β-CD and Ad-PNIPAM-12K/β-CD-PEO
7
1
9
g h
2]=0.02 g/L) the ratio of R /R
observation may imply that a hydrophilic layer consisting of β-CD-complexed with
Ad moieties forms at the periphery of the mesoglobules.
Finally, the R
h
of the supramolecular dumbbell-shaped compound was measured at
2°C with r = 2, as a function of concentration ranging in concentration Ad-PNIPAM-
2K from 0.0025 g/L to 0.04 g/L (Figure 10). We assume that under such conditions
5
1
solutions are sufficiently diluted and any changes of the size of the collapsed
aggregates are caused predominantly to their real growth upon increasing the
concentration. Thus way upon heating past the phase transition temperature Ad-
h
PNIPAM-12k formed aggregates of R ranging from 33 nm (0.0025 g/L of Ad-
1
9

Soft Matter
Page 20 of 37
View Article Online
DOI: 10.1039/C5SM01293G
PNIPAM-12K) to 75 nm (0.04 g/L of Ad-PNIPAM-12K). It is clearly observed that
the hydrodynamic radius of the aggregated supramolecular assembly is increasing
-
1
with its concentration, and seems to level off at a concentration close to 0.04 g.mol .
The preparation concentration is then a stimulus that allows to adjust the size of the
aggregate in the range 30 to 80 nm.
NMR experiments
1
D H NMR spectra of Ad-PNIPAM-12K and a mixed solution of Ad-PNIPAM-12K
1
7
and of β-CD-PEO (r = 1) were recorded as a function of increasing temperature using
3
-(trimethylsilyl)propionic-2,2,3,3-d4 acid sodium salt as an external reference. The
area of the signals between 0.6 and 2.5 ppm, attributed solely to PNIPAM, decreased
abruptly with increasing temperature between 22°C and 40°C. The transition mid-
points were 26°C in the case of Ad-PNIPAM-12K and 32.5°C in the mixed solution,
which are values similar to the Tm values recorded by HS-DSC. The small
discrepancies observed may be attributed to differences in solution concentration or to
44
the well-know effect of substituting D
The diffusion coefficient of the Ad-PNIPAM-12K/β-CD-PEO
solutions r = 1 heated to 39°C was evaluated by DOSY experiments (Table 1). The
2 2
O for H O .
7
complex in mixed
-11
diffusion coefficient of β-CD-PEO
7
in the mixed solution increased from 7.6×10
2 -10
m /s (23°C) to 1.6×10 (39°C), while the Ad-PNIPAM-12K diffusion coefficient
-11
2
-11
2
increased slightly, from 6.1×10 m /s (23°C) to 7.7×10 m /s (39°C). The diffusion
coefficient of β-CD-PEO in this solution is nearly identical to that of free β-CD-
PEO (1.7×10 m /s) recorded with a solution heated to 39°C. Hence, during the
7
-10
2
7
phase transition of the mixed solution, most of the β-CD-PEO
7
is expelled into bulk
water, indicating the lability of the Ad/CD inclusion complex and the preferred
2
0

Page 21 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
m
solubilization of Ad into the PNIPAM-rich phase formed above T . From LS
experiments, we concluded that the Ad-PNIPAM-12K aggregates formed above T
are surrounded by a layer of bound β-CD-PEO . The fraction of bound β-CD-PEO
compared to the β-CD-PEO released in bulk water must be too weak for detection via
m
7
7
,
7
DOSY measurements. All these results are reversible when decreasing the
temperature. To conclude, the NMR experiments allowed to characterize the behavior
of the self-assembly of Ad-PNIPAM-12K and β-CD-PEO
7
in function of the
temperature.
4
. Conclusion
The interactions at play in aqueous solutions of Ad-PNIPAM-12K and β-CD-PEO
below and above the phase transition temperature are depicted in Scheme 3. In very
dilute solutions, Ad-PNIPAM-12K and β-CD-PEO are kept apart. As the
temperature increases, the two polymers behave independently and Ad-PNIPAM-12K
aggregates form above the phase transition temperature, whereas β-CD-PEO remains
in water. As the concentrations of β-CD-PEO and Ad-PNIPAM-12K increase, the
7
7
7
7
inclusion complexes form between the β-CD cores of the star polymer and the
adamantyl groups borne by PNIPAM, in equilibrium with polymers. Heating the
solution leads to the formation of mesoglobules consisting of a core of aggregated
Ad-PNIPAM-12K collapsed chains surrounded by a β-CD-PEO
in bulk of unbound β-CD-PEO . In solutions of higher Ad-PNIPAM-12K and β-CD-
PEO concentrations, the mesoglobules formed above the phase transition increase in
7
shell and the release
7
7
size and further release of β-CD-PEO
suggesting possible applications
supramolecular systems as temperature-driven actuators.
7
occurs. All the phenomena are reversible,
of the
β-CD-PEO /Ad-PNIPAM-12K
7
2
1

Soft Matter
Page 22 of 37
View Article Online
DOI: 10.1039/C5SM01293G
Acknowledgments
This work was supported in part by the Natural Sciences and Engineering Council of
Canada-Discovery program (FMW) and by the World Premier International Research
Center Initiative (WPI, MEXT, Japan, FMW).
References
1
1
2
G. S. Kwon and T. Okano, Advanced Drug delivery Review 1996, 21, Issue 2, 107-
16.
K. Kataoka, A. Harada and Y. Nagasaki, Advanced Drug delivery Review 2001, 47,
Issue 1, 113-131.
B. M. Discher, Y. Y Won, D. S. Ege, J. C. M Lee, S. F. Bates, D. E. Discher and D.
A. Hammer, Science 1999, 284, n°5417, 1143-1146.
3
4
5
2
6
7
7
1
8
9
A. Harada, J. Li and M. Kamachi, Nature 1992, 356, 325 – 327.
N. Jarroux, P. Guégan, H. Cheradame and L. Auvray J. Phys. Chem. B 2005, 109,
3816-23822.
J. Li, X. Li, Z. Zhou, X. Ni and K. W. Leong, Macromolecules 2001, 34 (21),
236–7237.
A. Sandier, W. Brown, H. Mays and C. Amiel, Langmuir, 2000, 16 (4), 1634–
642.
A. Harada, J. Li and M. Kamachi, Nature 1993, 394, 516-518.
H. Fenneri, B. L. Deng, A. E. Ribbe, K. Hallenga, J. Jacob and P. Thiyagarajan
PNAS 2002, 99 (2) 6487-6492.
0 J. Couet and M. Biesalski, Soft Matter 2006, 2, 1005-1014.
1
2
2

Page 23 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
1
2
1
1 F. Yhaya, S. Binauld, Y. Kim and M. H. Stenzel, Macromol. Rapid Commun.
012, 33, 1868-1874.
2 C. De Vocht, A. Ranquin, R. Willaert, J. A. Van Ginderachter, T. Vanhaecke, V.
Rogiers, W. Versées, P. Van Gelder and J. Steyaert, Journal of Controlled Released
2
1
1
1
2
1
1
009, 137, 246-254.
3 N. Sakai and S. Matile, J. Am. Chem. Soc. 2003, 125 (47), 14348-14356.
4 N. Badi, L. Auvray and P. Guégan, Advanced Materials 2009, 21, 4054-4057.
5 L. Brunsweld, B. J. B. Folmer, E. W. Meijer and R. P. Sijbesma, Chem. Rev.
001, 101, 4071-4098.
6 M. Bellot and L. Bouteiller, Langmuir 2008, 24 (24), 14176-14182.
7 B. G. G. Lohmeijer and U. S. Schubert, J. of Polymer Science: part A: Polymer
Chemistry 2003, 41, 1413-1427.
1
8 K. J. Calzia, G. N. Tew, Macromolecules 2002, 35, 6090-6093.
1
9 L. Fang, S. Basu, C-H Sue, A. C. Fahrenbach and J. F. Stoddart, J. Am. Chem.
Soc. 2011, 133, 396–399.
2
2
2
2
2
2
2
2
0 C. F. J. Faul and M. Antonietti, Advanced Materials 2003, 15(9), 673-683.
1 S. A. Nepogodiev and J. F. Stoddart, Chem. Rev. 1998, 98, 1959-1976.
2 G. Wenz, B. H. Han and A. Müller, Chem. Rev. 2006, 106, 782-817.
3 Z-X. Zhang, K. L. Liu and J. Li, Macromolecules 2011, 44, 1182-1193.
4 C. Yang, H. Li, S. H. Goh and J. Li, Biomaterials 2007, 28, 3245-3254.
5 K. Ohno, B. Wong and D. M. Haddleton, J. Polym. Sci. Part A: Polym Chem
001, 39, 2206-2214.
6
J. Stadermann, H. Komber, M. Erber, F. Däbritz, H. Ritter and B. Voit,
Macromolecules 2011, 44, 3250-3259.
2
3

Soft Matter
Page 24 of 37
View Article Online
DOI: 10.1039/C5SM01293G
2
3
2
2
3
3
2
3
2
3
7 J. Zeng, K. Shi, Y. Zhang, X. Sun and B. Zhang, Chem. Commun., 2008, 3753-
755.
8 A. Bertrand, M. Stenzel, E. Fleury and J. Bernard, Polym. Chem 2012, 3, 377-383.
9 F. Yhaya, A. M. Gregory and M. H. Stenzel, Aust. J. Chem. 2010, 63, 195–210.
0 Z. Ge, H. Liu, Y. Zhang and S. Liu, Macromol. Rapid Commun. 2011, 32, 68-73.
1 B. V. K. J. Schmidt, M. Hetzer, H. Ritter and C. Barner-Kowollik, Polym. Chem
012, 3, 3064-3067.
2 X. Huan, D. Wang, R. Dong, C. Tu, B. Zhu, D. Yan and X. Zhu, Macromolecules
012, 45, 5941-5947.
3 Z-X. Zhang, X. Liu, F. J. Xu, X. J. Loh, E-T. Kang, K-G. Neoh and J. Li,
Macromolecules 2008, 41, 5967-5970.
3
4 B. V. K. J. Schmidt and C. Barner-Kowollik, Polym. Chem 2014, 5, 2461-2472.
3
5 C. Moers, L. Nuhn, M. Wissel, R. Stangenberg, M. Mondeshki, E. Berger-
Nicoletti, A. Thomas, D. Schaeffel, K. Koynov, M. Klapper, R. Zentel and H. Frey,
Macromolecules 2013, 46, 9544-9553.
3
6 L. Li, X. Guo, J. Wang, P. Liu, R. K. Prud’homme, B. L. May and S. F. Lincoln,
Macromolecules 2008, 41, 8677-8681.
3
2
3
7 M. Hetzer, B. V. K. J. Schmidt, C. Barner-Kowollik and H. Ritter, Polym. Chem.
014, 5, 2142-2152.
8
B. V. K. J. Schmidt, M. Hetzer, H. Ritter and C. Barner-Kowollik,
Macromolecules 2013, 46, 1054-1065.
9 Y. Inoue, P. Kuad, Y. Okumura, Y. Takashima, H. Yamaguchi and A. Harada, J.
Am. Chem. Soc. 2007, 129, 6396-6397.
3
4
6
0 H. S. Choi, K. M. Huh, T. Ooya, N. Yui, J. Am. Chem. Soc. 2003, 125, 6350-
351.
2
4

Page 25 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
4
1 G. Pouliquen, C. Amiel and C. Tribet, J. Phys. Chem. B 2007, 111, 5587-5595.
2 K. Lee, K. H. Bae, Y. Lee, S. H. Lee, C-H. Ahn and T. G. Park, Macromol.
4
Biosci. 2010, 10, 239–245.
4
5
4
4
4
3 W. Deng, H. Yamaguchi, Y. Takashima and A. Harada, Angew. Chem. 2007, 119,
236 –5239.
4 P. Kujawa and F. M. Winnik, Macromolecules, 2001, 34, 4130-4135.
5 S. Dai, P. Ravi and K. C. Tam, Soft Matter, 2009, 5, 2513–2533.
6 J. E. Chung, M. Yokoyama, T. Aoyagi, Y. Sakurai and T. Okano, J Controlled
Release, 1998, 53, 119–130.
4
2
4
4
7
5
5
4
5
7 Y. Xia, N. A. D. Burke and H. D. H. Stöver, Macromolecules, 2006, 39, 2275–
283.
8 V. Aseyev, H. Tenhu and F. M. Winnik, Adv. Pol. Sci, 2011, 242, 29-89.
9 P. Kujawa, V. Aseyev, H. Tenhu and F. M. Winnik, Macromolecules 2006, 39,
686-7693.
0 X. P. Qiu and F. M. Winnik, Macromolecules 2007, 40, 872-878.
1 F. Segui, X. P. Qiu and F. M. Winnik, J. Polym. Sci., Part A: Polym. Chem. 2008,
6, 314–326.
2 S. Nag, L. Duarte, E. Bertrand, V. Celton, M. Castro, V. Choudhary, P. Guegan
and J-F Feller, J. Mater. Chem. B 2014, 2, 6571–6579.
3 Y. El Ghoul, R. Renia, I. Faye, S. Rassou, N. Badi, V. Bennevault-Celton, C.
Huin and P. Guégan, Chem. Commun. 2013, 49, 11647-11649.
5
5
5
4 M. Holz and H. Weingärtner, J. Magn. Reson 1991, 92, 115-125.
5 V. Bennevault-Celton, A. Urbach, O. Martin, C. Pichon, P. Guégan and P.
Midoux, Bioconjugate Chem. 2011, 22, 2404-2414.
2
5

Soft Matter
Page 26 of 37
View Article Online
DOI: 10.1039/C5SM01293G
5
6 W. Schartl, Light Scattering from Polymer Solutions and Particle Dispersions,
Springer Verlag Berlin and Heidelberg, Germany, 2007, p. 18.
5
6
5
2
5
5
6
7 L. Lestel, P. Guégan, S. Boileau and F. Lauprêtre, Macromolecules 1992, 25,
024-6028.
8 J. Carrazana, A. Jover, F. Meijide, V. H. Soto and J. V. Tato, J. Phys. Chem. B
005, 109, 9719-9726.
9 X. P. Qiu, T. Koga, F. Tanaka and F. M. Winnik, Sci. China Chem. 2013, 56, n°1,
6-64.
0 P. Kujawa, F. Segui, S. Shaban, C. Diab, Y. Okada, F. Tanaka and F. M. Winnik
Macromolecules, 2006, 39, 341-348.
6
2
6
5
6
1
6
6
2
1 M. Othman, K. Bouchemal, P. Couvreur and R. Gref, Int. J. Pharm. 2009, 379,
18–225.
2 D. Li, G. Kagan, R. Hopson and P. G. Williard, J. Am. Chem. Soc. 2009, 131,
627-5634.
3 S. Viel, D. Capitani, L. Mannina and A. Segre, Biomacromolecules 2003, 4, 1843-
847.
4 T. Zhao and H. W. Beckham, Macromolecules 2003, 36, 4833-4837.
5 Y. J. Wang, H. Therien-Aubin, W. E. Baille, J. T. Luo and X. X. Zhu, Polymer
010, 51, 2345-2350.
2
6

Page 27 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
Figures, Scheme and Tables
O
O
S
O
S
n
O
O
n
O
O
NH
HN
Scheme 1. Structure of AdꢀPNIPAMꢀ12K.
N
N
OH
N
3
O
NaN
3
, DMF
OCH
3
n
N
O
O
OCH
3
n
O
O
O
CuSO
4
. H
2
O
HO
PPh
3
, CBr
4
HO
HO
O
RT, 48h
HO
O
Na Ascorbate
DMSO, RT
HO
7
7
HO
7
Scheme 2. Synthesis of heptakis[6ꢀdeoxyꢀ6ꢀ(1,2,3ꢀtriazoleꢀωꢀmethoxy poly(ethylene
oxide))]ꢀβꢀCD (βꢀCDꢀPEO7)
1

Soft Matter
Page 28 of 37
View Article Online
DOI: 10.1039/C5SM01293G
T=23°C
T=39°C
+
Highly
diluted
solution
+
K
diluted
solution
+
βꢀCDꢀPEO7
AdꢀPNIPAM
βꢀCDꢀPEO7
large excess of
free βꢀCDꢀPEO7
Concentrated
solution
Scheme 3 : Illustration of the selfꢀassociation of the AdꢀPNIPAMꢀ12K and βꢀCDꢀPEO7
mixture upon changes of concentration and temperature
H9, H10
H2
D
2
O
H11
H4
N
N
1
0
11
OCH
N
O
O
n
3
6
3
8
1
9
9
4
7
2
O
5
HO
HO
7
H6
H5
H6’
H8
H7
H1
H3
4.0
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
ppm
1
Figure 1: H NMR spectrum of feptakis[6ꢀdeoxyꢀ6ꢀ(1,2,3ꢀtriazoleꢀωꢀmethoxy
ꢀ4
poly(ethylene oxide)]ꢀβꢀcyclodextrin in D
2
7
O; [βꢀCDꢀPEO ]=6.25×10 mol/L
2

Page 29 of 37
Soft Matter
View Article Online
DOI: 10.1039/C5SM01293G
H9
H10
H3 H2
H5
H6
H11
H4
H6’
H8
H1
ppm
4
5
6
7
8
9
0
0
0
0
0
0
C6
C8
N
N
10
11
OCH3
C5, C11
N
O
O
n
6
3
8
1
9
4
7
9
C9, C10
C2, C3
O
2
5
HO
HO
C4
C1
7
1
00
7
.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0 ppm
(2a)
H9,H10
H2
H6
H6’ H5
H8
H11
H4
H3
H1
ppm
3
.4
.6
.8
.0
.2
.4
.6
.8
.0
.2
3
3
4
4
4
4
4
5
5
N
N
1
0
11
OCH3
N
O
O
n
6
3
8
9
9
4
7
O
2
5
1
HO
HO
7
5
.2 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4
ppm
(2b)
7
Figure 2: HSQC spectrum (Fig 2a) and COSY spectrum (Fig 2b) of βꢀCDꢀPEO in
ꢀ4
D
2
7
O at 25°C; [βꢀCDꢀPEO ]=6.25×10 mol/L
3