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and are useful for advanced technologies.13,14 However, their low
solubility and high glass transition temperature oen provide
problems with their application. In order to address these
problems, the use of semi-aromatic polyamides (synthesized via
a combination of aliphatic and aromatic monomers) is regar-
ded as a promising alternative. Semi-aromatic polyamides are
generally exploited to ll the “performance gap” between high-
performance polymers and nylons such as PA6.15 Such poly-
amides offer a wide range of properties including transparency,
outstanding strength-to-weight ratios, high thermal resistance,
and good barrier and solvent resistant properties, respec-
tively.16–21 In our latest work, a novel biobased semi-aromatic
polyamide (BPA) derived from nonanedioic acid and aromatic
diamine containing a pyridine group has been synthesized and
characterized.22 However, it has been found that while the use of
conventional nanoclay (Cloisite 30B) can slightly improve the
ame retardancy of BPA materials, it also severely decreases
their mechanical properties.
Scheme 1 Preparation of BPACD and BPAPO.
In order to obtain high performance biobased semi-aromatic
polyamide (BPA) nanocomposites, two new nanoclays were
synthesized and characterized by using two functional modi-
ers containing modied phosphine oxide and modied b-
cyclodextrin, respectively. BPA/organoclay nanocomposites
then were prepared via solution blending. Effects of the two new
organoclays on the morphology, thermal, ammability and
mechanical properties of the BPA nanocomposites were inves-
tigated, and our ndings are reported below.
150 mL of glacial acetic acid were reuxed for 18 hours. Upon
cooling, the precipitated yellow solid was collected by ltration
and washed with ethanol. The yield of the crude product was
68%, with a melting point of 285 ꢀC (see Scheme 1).
2.2.3 Synthesis of 4-(4-hydroxyphenyl)-2,6-bis(4-amino-
phenyl)pyridine. In a 250 mL round-bottomed ask equipped
with a reux condenser and a dropping funnel, a suspension of
the synthesized dinitro compound (5 g, 12 mmol); palladium on
carbon 10% (0.1 g); ethanol (30 mL); and dimethylformamide
(DMF, 5 mL) was prepared. The mixture was warmed, and while
being stirred magnetically, hydrazine monohydrate 80% (10 mL)
in ethanol (15 mL) was added dropwise over a 1 hour period
through a dropping funnel, while keeping the temperature at
about 70 ꢀC. Aer 4 hours, the mixture was ltered while hot to
remove Pd/C, and the solvent then evaporated under vacuum to
afford the yellow solid product (yield, 94%; melting point, 230 ꢀC;
1H NMR (500 MHz, DMSO) d, ppm: 9.7 (s, 1H), 8.0 (d, 4H), 7.8 (d,
2H), 7.7 (s, 2H), 6.9 (d, 2H), 6.7 (d, 4H), 5.4 (d, 4H); see Scheme 1).
2.2.4 Synthesis of biobased aliphatic–aromatic polyamide.
4-(4-hydroxyphenyl)-2,6-bis(4-aminophenyl)pyridine (5 g, 14
mmol); nonanedioic acid (2.7 g, 14 mmol); calcium chloride
(0.5 g, 4.5 mmol); triphenyl phosphite (8.7 mL, 28 mmol);
pyridine (1 mL); and N-methyl-2-pyrrolidone (8 mL) were added
to a 50 mL round-bottomed ask tted with a stirring bar. The
reaction mixture was heated under reux in an oil bath atꢀ60 ꢀC
2. Experimental
2.1 Materials
b-cyclodextrin, allyl glycidyl ether (AGE) and (3-chloro-2-
hydroxypropyl)trimethylammonium chloride (CMA) were
obtained from ABCR GmbH & Co. KG in Germany, and used
without further purication. Triphenylphosphine oxide, palla-
dium charcoal, N-methyl-2-pyrrolidone (NMP), N,N-dimethyla-
cetamide (DMAc), hydrazine hydrate, pyridine, nitric acid,
sulfuric acid, methanol, triphenyl phosphite (TPP), oleic acid, 4-
nitroacetophenone,
4-hydroxybenzaldehyde,
ammonium
acetate, potassium permanganate (KMnO4) and glacial acetic
acid obtained from Aldrich were used without further puri-
cation. Sodium montmorillonite (NaMMT; unmodied having
CEC ¼ 92.6 meq. per 100 g clay) from Southern Clay Products,
Inc. was used.
ꢀ
for 1 hour, then at 90 C for 3 hours, and nally at 120 C for
Commercially available calcium chloride (CaCl2, Aldrich)
ꢀ
8 hours. The reaction mixture was then poured into 100 mL of
methanol, and the precipitated product collected by ltration
and washed thoroughly with hot methanol. Finally, the product
was dried at 60 ꢀC for 12 hours in a vacuum oven until a
constant weight was attained (yield, 95%).
was dried under vacuum at 150 C for 6 hours.
2.2 Synthesis of semi-aromatic biobased polyamide (BPA)22
2.2.1 Synthesis of nonanedioic acid from oleic acid.
KMnO4 was used to oxidize the double bond of the oleic acid,
forming nonanedioic acid, following procedures in the litera-
ture23 (yield: 67%).
2.2.2 Synthesis of 4-(4-hydroxyphenyl)-2,6-bis(4-nitrophenyl)
pyridine. In a 500 mL round-bottomed ask, a mixture of 5.0 g
2.3 Synthesis of b-cyclodextrin based modier (CD-DB-N+)
and tris(3-aminophenyl)phenyl phosphine oxide based
modier
(41 mmol) of 4-hydroxybenzaldehyde; 13.5 g (82 mmol) of In a 50 mL round-bottomed ask, 4.54 g b-CD (4 mmol) was
4-nitroacetophenone; 76.5 g (1.0 mol) of ammonium acetate; and added with stirring to an aqueous solution composed of 15 mL
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RSC Adv., 2014, 4, 23420–23427 | 23421