Synthesis, characterzation, and evaluation of amine-terminated cycloaliphatic-substituted polysiloxanes

摘要

Cyclopentyl- and cyclohexyl-substituted polysiloxanes terminated with amino groups were prepared. Initially, the cycloalkene and dichlorosilane were reacted at high pressure (approx. 250 psi) and high temperature (120 degrees C) to yield the cycloaliphatic dichlorosilane in a two-step process. Both the mono- and disubstituted chlorosilane monomers underwent an oligomerization to produce cyclic oligomers of low molecular weight (approximate to 2 000 g center dot mol(-1)). Amine -terminated polysiloxanes were produced via a base-catalyzed ring-opening polymerization of the cyclic oligomers with 1,3-bis(3-aminopropyl)tetramethydisiloxane to yield low molecular weight polysiloxanes ( approximate to 9 000 g center dot mol(-1), amine equivalent weight =approximate to 4 300 g center dot equiv(-1)). The polysiloxanes were characterized by H-1 and Si-29 NMR, and Fourier transform-infrared spectroscopy (FT-IR). The amine -terminated polysiloxane was mixed with a cycloaliphatic epoxy-functionalized cycloaliphatic polysiloxane in order to produce crosslinked epoxy-amine films. The mechanical and physical properties of the film were evaluated and afford a glass transition of the material was 29.5 +/- 0.7 degrees C for the cyclopentyl-substituted polysiloxane and 38.6 +/- 0.7 degrees C for the cyclohexyl-substituted polysiloxane. Evaluation of pull-off adhesion indicated that 0.5 MPa of normal force was required to remove the epoxy/amine film from an aluminum substrate.