Siloxanes epoxy-terminated, preparation

Poly(unsaturated ester)-siloxane segmented copolymers have been prepared by the polycondensation of epoxy-terminated polydimethylsiloxanes and carboxy-terminated poly(ethylene adipate-co-maleate) oligomers 243). Reactions have been conducted in cellosolve solvent, at 140-150 °C, in the presence of 2% by weight potassium hydroxide catalyst. The molecular weights reported were fairly low. The same group has also prepared poly(hexamethylene adipate)-polydimethylsiloxane copolymers con-... 

Siloxane-modified networks were prepared for testing via two steps. A linear precursor was generated by reacting the epoxy resin with the siloxane oligomer for one hour under vacuum at 65 °C. PACM-20 was then added, and the mixture was stirred for five minutes under vacuum at 50 °C. Previous studies indicated 151 that reaction between the AEP-terminated siloxane oligomers and the curing agent is not possible, as one would expect. 

Branched copolymers of PDMS and poly(caprolactone) have been prepared as shown in equation 13. They were incorporated into epoxy resin via reaction at the terminal hydroxy groups and acted as toughening agents, with a three-fold increase in impact strength being observed with 5 wt% of 36 present. The siloxane phases were in the range of 10-20 mn, resulting in an optically clear material ... 

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