Kinetics, mechanisms, and synthesis studies of difunctional aminopropyl terminated polydimethylsiloxane oligomers

Abstract

The anionic ring opening equilibration polymerization of octamethylcyclotetrasiloxane (D4) initiated with siloxanolates in the presence of 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane (DSX) was investigated. The disiloxane serves as an effective chain transfer agent and source of aminopropyl functionality. Techniques for following the polymerization utilizing gas chromatography and high pressure liquid chromatography (HPLC) were developed and verified to be comparable with alternate methods published in the literature. In these polymerizations, it was concluded that the quaternary siloxanolate led to much more rapid polymerizations than the corresponding potassium based initiators. In all cases, the cyclic tetramer disappeared more rapidly than the disiloxane. However, this does not limit the utilization of the DSX for the synthesis of controlled molecular weight, difunctional species. Polar impurities, such as water in the disiloxane, were shown to influence the reactivity in these systems, especially at relatively low initiator concentrations. The work is continuing and many issues are being addressed, currently in a more quantitative fashion using the analytical procedures developed in the current study.

A new cross‐linked system of silicone rubber based on silicone‐polyurea block copolymer

“…α,ω‐bis‐Aminopropyl polydimethylsiloxane (A‐PDMS) was synthesized by 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane and octamethylcyclotetrasiloxane through anionic ring‐opening polymerization according to the open literatures . The molecular weight of A‐PDMS was determined by end‐group analysis based on the integration of the peak areas of 1 HNMR and was calculated to be 12 795 g/mol.…”

“…Also, the linear correlations between polyurea contents and the thermal properties as well the surface properties had been reported. 31,32 The molecular weight of A-PDMS was determined by end-group analysis based on the integration of the peak areas of 1 HNMR and was calculated to be 12 795 g/mol. Bis(4isocyanatocyclohexyl)-methane (HMDI) with a purity better than 99.5% was supplied by Huainan Kedi Chem Co., China.…”

Methods for the Preparation of Modified Polyorganosiloxanes (A Review)

“…Often, it is used to obtain POS of block, alternating structure, using functionalized cyclosiloxanes. [28][29][30][31][32] However, anionic polymerization is complicated by its conditions. This method is extremely sensitive to the inertness of medium, the purity of reagents and solvents, and the presence of impurities.…”

Synthesis, characterization, and comparison of properties of novel fluorinated poly(imide siloxane) copolymers

“…The main goal of all such approaches is the reduction of polymer chain–chain interactions, reduction of chain packing and charge‐transfer electronic polarization interactions. In this respect, the incorporation of the flexible siloxane segment into the polyimide backbone imparts enhanced solubility, reduced water sorption, increased gas permeability, good thermal and ultraviolet stability, resistance to degradation in aggressive oxygen environments, impact resistance, and modified surface properties 22–26. These interesting properties make polysiloxane‐modified polyimides useful materials for aerospace applications and electronic devices.…”