An Improvement of Mechanical Properties of Two Kinds of Silicone Resins Containing Ladder Segments by Chemical Modification with Trimethylborate.

We suggest a new method for postsynthesis modification of silicones containing silanol groups. It was found that trimethylborate is an effective catalyst for dehydrative condensation of silanol groups with the formation of ladder-like blocks. The utility of this approach was demonstrated on postsynthesis modification of poly-( poly(dimethylsiloxane)- ladder-like poly(phenylsiloxane)) and poly-( poly((3,3',3″-trifluoropropyl-methyl)siloxane)- ladder-like poly(phenylsiloxane) with a combination of linear and ladder-like blocks having silanol groups. The postsynthesis modification leads to a 75% increase in tensile strength and 116% elongation on break in comparison with the starting polymer.