Synthesis, Characterization, and Properties of Hydroxyl-Terminated Copolysiloxanes Containing γ-Cyanopropyl Groups

A series of random copolysiloxanes (PCDMS) containing various amount of -cyanopropyl groups are prepared by a new method under mild conditions. Structures of the synthesized polymers are fully characterized by FTIR, H-1 NMR, Si-29 NMR, and GPC. Rheological properties of PCDMS are tested by cone and plate rheometer, and thermal properties by differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). Damping properties as well as fuel resistance of the cured PCDMS elastomers are also tested. The correlation between chemical structure, content of cyanopropyl group and properties are discussed. With the increasing amount of polar cyanopropyl group introduced, glass transition temperatures (T-g) of the synthesized PCDMS gradually increases from -121 to -65 degrees C, residual weight increases from 0 to 36% at 800 degrees C, loss factor reaches as high as 1.74, mass increase under fuel immersion for 14 days can be as low as 3.6%. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1408-1421