Thermotropic liquid crystalline polyesters derived from bis-(4-hydroxybenzoyloxy)-2-methyl-1,4-benzene and aliphatic dicarboxylic acid chlorides

Abstract

A series of thermotropic liquid crystalline polyesters derived from bis-(4-hydroxybenzoyloxy)-2methyl-1,4-benzene (BHBOMB) and aliphatic dicarboxylic acid chlorides were investigated. All these polyesters were synthesized by interfacial polycondensation method and characterized by differential scanning calorimetry and wide-angle X-ray diffractometer. These polyesters consist of BHBOMB as a mesogenic diol and aliphatic diacid chlorides were used as flexible spacers. The length of oligomethylene units in polymer was varied from the trimethylene to the dodecamethylene groups. The transition temperatures and thermodynamic properties were studied for all these polymers. All these polyesters were soluble in chlorinated solvents such as chloroform, dichloromethane, dichloroethane, etc. More importantly, all these polyesters exhibited very large mesophase stability.

Thermotropic liquid crystalline polyesters derived from 2-chloro hydroquinone

“…The incorporation of methyl substituent on hydroquinone central moiety of triad mesogen unit resulted in lower isotropisation temperature with respect to the similar number of methylene units. 18 In short, crystal to liquid crystal transition temperatures of unsubstituted hydroquinone based polyesters were higher than those of the methyl and chlorohydroquinone based polyesters. The trend of crystal to liquid crystal transition temperature of polyesters based on hydroquinone is as follows: H > Me > Cl.…”

“…16 In our previous papers, we reported the synthesis and characterization of thermotropic liquid crystalline polyesters derived from hydroquinone and methyl hydroquinone-based rigid rod diols as mesogenic units and aliphatic dicarboxylic acids as flexible spacers. 17,18 The present investigation demonstrates synthesis and characterisation of TLCP derived from bis[4-hydroxy benzoyloxy]-2-chloro-1,4-benzene (BHBOCB) as mesogenic moiety and aliphatic diacid chloride as flexible spacer. Flexible spacer was inserted into the backbone of the rigid polymer to dissociate the greater order of the main-chain and decouple the motion of mesogenic moiety from polymer backbone.…”

“…Mesophase stability of hydroquinone, methyl hydroquinone and chlorohydroquinone-based polyesters showed significant difference in mesophase stability on the basis of second heating cycle in which thermal history was eliminated. 17,18 Mesophase stability of the substituted hydroquinone (e.g., methyl or chloro)-based rigid-rod flexible spacer polymers showed higher than unsusbtituted polymers on the basis of second heating cycle. Maximum mesophase stabilities were observed 198.4, 163.1 and 107.8 • C for chloro, methyl and unsubstituted hydroquinone-based polymers, respectively, whereas minimum mesophase stabilities were observed 123.0, 89.8 and 99.8 • C for chloro, methyl and unsubstituted hydroquinone-based polymers, respectively.…”

Cytotoxic Anti-Cancer Activity of Certain Thermotropic Liquid Crystalline Poly (Ester-Amides) Containing 2, 6-Bis (Benzylidene)Cyclohexanone Moiety in the Main Chain

“…In these polymers, an exothermic peak appears before melting transition, which seems to be related to crystal to crystal transition resulted from different crystalline polymorphs. 14 The liquid crystalline range ( of the poly(ester-amide) derived from terephthalic acid monomer is broader than compared to the poly(ester-amide) derived from other monomers. This may be due to effective molecular packing by coplanar geometry.…”

Thermotropic Liquid Crystalline Polyesters Using Aromatic Rigid Diols, Unsaturated Fumaric Acid and Flexible Sebacic Acid

“…Liquid crystalline thermosets are a class of materials that combine properties typical of thermotropic liquid crystalline polymers with those of conventional thermosets. Mulani et al [12] observed very large mesophasic stability for new liquid crystalline polyesters consisting of bis-(4hydroxybenzoyloxy)-2-methyl-1,4-benzene and aliphatic dicarboxylic acid chlorides [12]. Applications of liquid crystal thermosets include the advanced adhesives, new matrix materials for composites and variety of applications for microelectronics industry.…”