The synthesis and evaluation of novel polysiloxane Langmuir-Blodgett films

Two aliphatic acid side-chain polymers have been synthesised and evaluated, based on two different polysiloxane backbones, poly(hydrogenmethylsiloxane) and poly(hydrogenmethyldimethylsiloxane). A study of their Langmuir film forming properties has shown that monolayer films are formed at the air-water interface. Transferred LB films have been prepared using the alternate layer deposition method in which the polysiloxane monolayer is co-deposited with a monomeric aliphatic amine (icosylamine). The linear relationship between the change in resonance frequency of a piezoelectric quartz crystal oscillator and the number of deposited bilayers has confirmed the reproducibility of the transfer process. Some of the electrical properties of these films have been characterised including permittivity, dielectric loss and their pyroelectric behaviour. Importantly, the pyroelectric activity of the copolymer polysiloxane/icosylamine monomer alternate layer films is larger than that exhibited by the homopolymer films suggesting that the mechanism(s) by which the pyroelectric effect originates depends upon the free volume available to the acid pendant side-chains attached to the polysiloxane backbone.