Mesomorphic poly(di-n-alkylsiloxane)s crosslinked in the acrylate matrix
Polimery 2001, No 7-8, 476
SummaryCrosslinked acrylate-siloxane copolymer networks containing higher than methyl (Et, n-Bu) substituents at the silieon atom, were prepared by photopolymerization of tetrafunctional siloxane prepolymers [(V), Scheme B] in the isobutyl acrylate (i-BA) matrix. Synthesis of the prepolymers is described in detail (Schemes A and B, Table 1). As expected, the group of elastomeric copolymers of such a structure generated the mesomorphic "condis" (conformationally disordercd crystal) phase within a room temperature range, 7-36 °C (Table 2). The resulting materials varied in nature from waxes through elastomers to plastic systems depending on the molecular weight of the starting siloxane prepolymers, the nature of the side alkyl substituent (Et or n-Bu) at the silicon atom, and the i-BA/siloxane ratio. Atomic Force Microscopy (AFM) of the free standing surface showed the microscopic characteristics of the copolymers to be affected by microseparation, viz., by the size of the siloxane and the acrylate domains. The extent of phase separation was found to be related to the network components ratio.