Chemistry of Silanes: Interfaces in Dental Polymers and Composites.
The performance and service life of glass-or ceramic-filled polymeric composites depend on the nature of their resin, filler and interfacial phases as well as the efficacy of the polymerization process. The synergy that exists between the organic polymer matrix and the usually inorganic reinforcing filler phase is principally mediated by the interfacial/interphasial phase. This latter phase develops as a result of the dual reactivity of a silane coupling agent, (YRSiX3), a bifunctional molecule capable of reacting with the silanol groups of glass or ceramic fillers via its silane functional group (-SiX3) to form Si-O-Si- bonds to filler surfaces, and also with the resin phase by graft copolymerization via its Y functional group, usually a methacrylic vinyl group. In this paper, we explore some of the chemistry of organosilanes, especially that of functional organosilanes (or silane coupling agents as they are commonly known) that are used to mediate interfacial bonding in mineral reinforced polymeric composites. The chemistry of organosilanes can be quite complex involving hydrolytically initiated self-condensation reactions in solvents (including monomers) that can culminate in polymeric silsesquioxane structures, exchange reactions with hydroxylated or carboxylated monomers to form silyl ethers and esters, as well as the formation of silane derived interfaces by adhesive coupling with siliceous mineral surfaces.
National Institute of Standards and Technology, 100 Bureau Drive, Stop 8545, Gaithersburg, MD 20899 USA.
Joseph M
JM
Antonucci
American Dental Association Foundation, Paffenbarger Research Center, 100 Bureau Drive, Stop 8546, Gaithersburg, MD 20899 USA.
Sabine H
SH
Dickens
National Institute of Standards and Technology, 100 Bureau Drive, Stop 8545, Gaithersburg, MD 20899 USA.
Bruce O
BO
Fowler
American Dental Association Foundation, Paffenbarger Research Center, 100 Bureau Drive, Stop 8546, Gaithersburg, MD 20899 USA.
Hockin H K
HH
Xu
National Institute of Standards and Technology, 100 Bureau Drive, Stop 8545, Gaithersburg, MD 20899 USA.
Walter G
WG
McDonough
adhesion; interfacial adhesion; interphases; silanes; silanization; silsesquioxanes