Preparation, Characterization, and Rheological Behaviors of Polysiloxanes Presenting Densely Simple and Well-Defined Short-Branched Chains

In this paper, a series of polysiloxanes, presenting different contents of densely simple and well-defined short-branched chains (G1–G5), are prepared by hydrosilylation of α,ω-(dimethylvinylsiloxy)-poly(dimethyl-methylvinyl)siloxanes (P1–P5) with 1,1,1,3,5,5,5-heptamethyltrisiloxane (MDHM) and characterized by 1H and 29Si nuclear magnetic resonance, Fourier transform-infrared spectroscopy, Abbe refractometry, gel permeation chromatography, and differential scanning calorimetry. The rheological behaviors of the G1–G5 products are investigated to study the influences of the short-branched chains. The rheological parameters including non-Newtonian index (n) and the flow activation energy (ΔEη) are obtained and discussed. It is observed that the G1–G5 polymers belonged to pseudoplastic fluids and the ΔEη values of the G1–G5 products are significantly influenced by the short-chain branching degree of the polymers.