Metathesis-curable composition with a reaction control agent

A composition capable of undergoing a metathesis reaction upon mixing of its components, the components comprising:

• an olefin-containing substrate comprising at least one oligomer or polymer having a >20 wt. % linear siloxane (Si—O—Si) backbone functionalized with olefin groups capable of undergoing a metathesis reaction, wherein the at least one oligomer or polymer is selected from the group consisting of:
• a telechelic oligomer or polymer end-capped with the olefin groups, an oligomer or polymer tethered and end-capped with the olefin groups, a tri-functional oligomer or polymer end-capped with the olefin groups, and a quadri-functional oligomer or polymer end-capped with the olefin groups;
• a ruthenium carbene complex catalyst capable of initiating the metathesis reaction in the composition, wherein the catalyst has the formula:
• wherein:
• M is ruthenium or osmium,
• X is an alkylidene ligand with basicity higher than that of tricyclohexylphosphine (PCy3),
• Z is oxygen (O) or sulfur (S)
• X2 and X3 are either the same or different and are any anionic ligand, and
• R4, R5, a, b, c, and d are the same or different and are each a linear, branched, cyclic or polycyclic organic residue optionally containing siloxane groups (Si—O—Si) and optionally containing heteroatoms selected from the group consisting of B, N, O, Si, P, and S;
• and
• at least one reaction control agent for slowing the progress of the metathesis reaction after mixing the composition components and having the structure:
• wherein:
• G is selected from the group consisting of:
• L3,
• L is a hydrocarbon fragment containing an allyl group, a vinyl group, an ethynyl group or a propargyl group,
• L1-L9 are each independently selected from the group consisting of L, alkyl, aryl, aralkyl or haloalkyl,
• A is a Group 14 atom,
• n=0-20, and
• m=0-20.

A curable composition comprising:

• an olefin-containing substrate comprising at least one oligomer or polymer having a >20 wt. % linear siloxane (Si—O—Si) backbone functionalized with cycloalkenyl groups capable of undergoing a metathesis reaction;
• a ruthenium carbene complex catalyst capable of initiating the metathesis reaction in the composition, wherein the catalyst has the structure:
• wherein R4 is isopropyl, ethyl or methyl, and c is hydrogen, methoxy or ethoxy;
• and
• a reaction control agent for slowing the progress of the metathesis reaction, wherein the reaction control agent is tetraallyl silane or tetraallyloxysilane.