Synthesis, characterization and liquid crystalline properties of polyacrylates and polymethacrylates containing aryl ester pendant unit

Abstract

Aryloxycarbonylphenyl acrylates and methacrylates were prepared by reacting 4-acryloyloxybenzoyl chloride and 4-methacryloyloxybenzoyl chloride with different phenols. They were homopolymerized using benzoyl peroxide as the initiator at 65°C in dimethylformamide. The polymers were characterized by IR and 1 H-NMR spectra and size exclusion chromatography. Differential scanning calorimetry and polarizing optical microscopy studies revealed that the phenyl esters of poly(4-acryloyloxybenzoic acid) and poly(4-methacryloyloxybenzoic acid) did not show any liquid crystalline properties, but, the para-aryl-substituted phenyl esters did exhibit mesophase properties in the temperature range of 98 -265°C depending on the nature of the aryl substituent. Polymethacrylates exhibit higher T g , and lower T m and T i than the polyacrylates having the same pendant mesogen. Thermogravimetric analyses have shown that the initial decomposition temperatures of the polymers are above 230°C.

Reinforcement of high density polyethylene with a side chain LCP by graft copolymerization—thermal, mechanical and morphological properties

“…ABC was prepared by refluxing ABA, synthesized by condensation reaction of p-hydroxybenzoic acid with acryloyl chloride in alkaline medium as reported previously by Sainath et al [23], with thionyl chloride in the presence of a trace amount of dimethyl formamide for 5-6 h. In all stages, the structures of the products ABA, ABC and BPOCPA were confirmed by FTIR and 1 H-NMR techniques, and the products were characterized by DSC analysis. The results correlated well with the literature [24].…”

“…The greater chain mobility and the intensifying cohesive forces have consistently given rise to probably maximum alignment and ordering of PE chains in the crystallites of the sample with 13.7 % poly(BPOCPA), and thus to the maximum melting temperature, 137.7°C among the coproducts. Furthermore, the glassy nematic structured poly(BPOCPA) units [23] may act as nucleating agents additionally conducing to more ordered packing of PE chains in crystallites. The decrease in the melting point at further poly(BPOCPA) contents, however, can be explained by diminutions in the ordered packing of the chains compared to 13.7 % poly(BPOCPA) sample due to the reduced chain mobility in the shrinked ab basal area with respect to virgin PE unit cells.…”

“…4). The glassy nematic structured poly(BPOCPA) units [23] acting as nucleating agents, conducing to more ordered packing of PE chains in crystallites, might have resulted in the large sized crystals. In addition, the possibly higher chain mobility, accompanying the largest unit cell dimensions at 5 % poly(BPOCPA) among the coproducts, Fig.…”

“…These improvements were believed to result from the developments in the orientation of PE chains due to the constitution of side chain LCP poly(BPOCPA) molecules as graft units. The regularly organized structure of poly(BPOCPA) molecules with glassy nematic phase [23] probably led to enhancement in the orientation and alignment of PE chains, thus to advanced mechanical property in the coproducts. The notably significant increases in the melting temperature of PE supported the interpretation of the mechanical improvements owing to the advance in the orientations of the molecules.…”

“…The mesomorphic properties of the side chain LCP, poly(pbenzophenoneoxycarbonylphenyl acrylate), poly(BPOCPA) was studied by Sainath et al [23]. In their study, poly(BPOCPA) was reported to exist in non-crystalline, glassy nematic order with phase transitions at 145-199°C.…”