Journal of Polymer Science Part A: Polymer Chemistry, Vol.35, No.13, 2653-2688, 1997
Model Reactions and Formation of Epoxy Networks with the Phenylbenzoate Mesogen
The phenylbenzoate mesogen was introduced into epoxy networks by the crosslinker 4-hydroxyphenyl-4-hydroxybenzoate and by the diglycidylether of 4-hydroxyphenyl-4-hydroxybenzoate, respectively. Rigid networks were synthesized on the basis of 4-hydroxyphenyl-4-hydroxybenzoate and the diglycidylether of bisphenol A, and flexible networks were prepared by reaction of the diglycidylether of butanediol-1.4 with the same dihydroxy compound. Model investigations were used to obtain information about the reactivity differences of the phenolic hydroxyl groups of the bisphenol used for network formation. Furthermore, the thermal properties of the main products isolated from the model reactions are strongly influenced by the substituents at the phenylbenzoate structure. Some of these model substances demonstrate structures that can be also found in the networks. In addition, photoinduced cationic crosslinking of the diglycidylether of 4-hydroxyphenyl-4-hydroxybenzoate results in networks with different thermal properties that are dependent on the temperature of network formation. Moreover, the temperature used during crosslinking influences the formation of ordered structures in the networks.
Keywords:LIQUID-CRYSTALLINE ACRYLATES;ORIENTED POLYMER NETWORKS;BISPHENOL-A;INSITU PHOTOPOLYMERIZATION;IMIDAZOLE CATALYSIS;THERMAL-EXPANSION;CURING REACTION;MAIN CHAIN;THERMOSETS;RESINS