Functional polysiloxane oligomers

By the authors [26] the novolac-epoxy networks was modified with reactive epoxy functional polysiloxane oligomers containing various levels of polar nitrile pendent groups was investtigated. It was shown that the using with high content of polysiloxanes as an elastomeric modifiers component in epoxy-novolac networks exhibited micro phase separation. 

Detailed information on the copolymerization of cyclic trifluoropropylmethyl-siloxane trimer and octamethylcyclotetrasiloxane is also very limited in the open literature26 27 . Recently, preparation of various amine terminated (dimethyl-tri-fluoropropyl,methyl)siloxane oligomers with varying molecular weights and backbone compositions has been reported 69115 ll7). Table 11 shows various properties of the oligomers produced as a function of composition. These types of modification play very important roles in determining the solubility characteristics and hence the compatibility of resultant polysiloxanes with other conventional organic monomers... 

Polycondensation of difunctional oligomeric cyclodisilazanes with a,co-dihydroxypolysiloxanes proved to be another successful attempt to synthesize silazane modified polysiloxanes of improved thermostability. The cyclodisilazane oligomers IHa (see scheme below) are readily available from common and cheap materials, dichlorodimethylsilane and ammonia (fi). The chlorine atoms in these compounds can be easily exchanged to other functional groups, such as amino, hydroxyl, etc. 

In Chapter 3, the chemistry and technology of the most important oligo-polyols used for elastic polyurethanes fabrication, in fact high MW oligomers (2000-12000 daltons) with terminal hydroxyl groups and low functionality (2-4 hydroxyl groups/mol) were discussed. Polyalkylene oxide polyols (homopolymers of PO or copolymers PO - EO, random or block copolymers), polytetrahydrofuran polyols, filled polyols (graft poly ether polyols, poly Harnstoff dispersion - polyurea dispersions (PHD) and polyisocyanate poly addition (PIPA) polyols), polybutadiene polyols and polysiloxane polyols were all discussed. The elastic polyurethanes represent around 72% of the total polyurethanes produced worldwide. 

Riffle, J. S. Yilgor, I. Tran, C. Wilkes, G. L. Mcgrath, J. E. Bantia, A. K. Elastomeric Polysiloxane Modifiers for Epoxy Networks. Synthesis of Functional Oligomers and Network Formation Studies Epoxy Resin Chemistry II , ACS Symp. Sen, 1983, ,2i,... 

In other approaches, the polysiloxane [e.g. poly(dimethylsiloxane), poly(oxydimethylsilylene)] is furnished with functional organic end groups which are employed in subsequent conventional copolycondensation reactions. Thus polycarbonate-PDMS block polymers, which have been studied in considerable detail, are obtained by end-capping a,cu-dichloro-PDMS with bisphenol A to give reactive oligomers (36) which are converted to block copolymers (37) by co-phosgenation with further quantities of the bisphenol (equation 28). 

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