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Documented auxetic behaviour and our site-connectivity driven rigid rod re-orientation approach to the design of auxetic polymers is overviewed. A number of main-chain liquid crystalline (LC) polymers and lightly crosslinked polymers incorporating p-terphenyl rods, and some pentaphenyl rods, capable of 90° re-orientation have been synthesized. It was found that the mesophase transition temperature of the parent LC polymer can be tailored by varying the ratio of trisiloxane and octasiloxane spacer. Poisson's ratio measurements have been obtained for parent elastomers having variable crosslink density and with variable terphenyl rod incorporation. The trends in Poisson's ratio were correlated with chemical and network structure. A Smectic C layer structure was observed for most linear and networked materials. [ABSTRACT FROM AUTHOR]

Documented auxetic behaviour and our site-connectivity driven rigid rod re-orientation approach to the design of auxetic polymers is overviewed. A number of main-chain liquid crystalline (LC) polymers and lightly crosslinked polymers incorporating p-terphenyl rods, and some pentaphenyl rods, capable of 90° re-orientation have been synthesized. It was found that the mesophase transition temperature of the parent LC polymer can be tailored by varying the ratio of trisiloxane and octasiloxane spacer. Poisson's ratio measurements have been obtained for parent elastomers having variable crosslink density and with variable terphenyl rod incorporation. The trends in Poisson's ratio were correlated with chemical and network structure. A Smectic C layer structure was observed for most linear and networked materials. [ABSTRACT FROM AUTHOR]

Documented auxetic behaviour and our site-connectivity driven rigid rod re-orientation approach to the design of auxetic polymers is overviewed. A number of main-chain liquid crystalline (LC) polymers and lightly crosslinked polymers incorporating p-terphenyl rods capable of 90° re-orientation have been synthesized. It was found that the mesophase transition temperature of the parent LC polymer can be tailored by varying the ratio of trisiloxane and octasiloxane spacer. Parent LC polymer containing longer biphenyl type mesogenic unit can retain liquid crystalline order even with 75% transverse rod loading. X-ray diffraction detects orthogonal layer structure and smectic C tilted layer structure in parent biphenyl LC polymer and the polymer with auxetic rod, respectively. A synthetic route to a PET type polymer incorporating p-pentaphenyl transverse rod is proposed as our future work. [ABSTRACT FROM AUTHOR]