Reducing polymerization-induced shrinkage stress by reversible addition-fragmentation chain transfer
AssigneeThe Regents of the University of Colorado, a body corporate
InventorsChristopher Bowman, Diana Leung
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Abstract
The invention provides methods of reducing shrinkage stress in cross-linked polymerized materials by combining an addition-fragmentation chain transfer additive with a resin system prior to polymerization. The methods of the invention can improve the performance of conventional resin systems by reducing the shrinkage stress without significantly degrading the mechanical properties of the polymerized material. The shrinkage stress in the crosslinked polymeric materials produced by the methods of the invention may be from 25% to 75% of that of a control material produced by polymerization of the resin system alone to the same conversion.
Claims19
1) A method for reducing internal stress in a crosslinked polymeric material, the method comprising the steps of
- a) forming a mixture by combining a RAFT additive comprising a RAFT functional group with a system comprising an initiator and at least one monomer having at least two polymerizable functional groups, wherein the molar ratio of RAFT functional groups to polymerizable functional groups in the system is from 0.005 to 0.05;
- and
- b) polymerizing the mixture to form a cross-linked polymeric material with at least 50% conversion of the polymerizable functional groups.
Dependencies are inferred from the claim text.