Synthesis and Evaluation of New Oxaspiro Monomers for Double Ring-opening Polymerization

Abstract

Polymerization with expansion in volume can be achieved with spiro orthocarbonate monomers through a double ring-opening process wherein two bonds are cleaved for each new bond formed. The resulting expansion can be applied to counter the polymerization shrinkage associated with the conventional methacrylate monomers used in dental composites and thereby provide formulations with drastically reduced degrees of shrinkage. New monomers have been prepared that exhibit enhanced reactivities and ring-opening efficiencies compared with earlier free-radical-polymerizable oxaspiro compounds. In dental composite formulations, the monofunctional oxaspiro monomers provided DTS values equivalent to those of the controls under certain curing conditions; however, only modest reductions in polymerization shrinkage were observed.

2,3-Bis(methylene) spiro orthocarbonate monomers with a conjugated diene structure were also synthesized and evaluated. These novel monomers appear to offer significant potential for future development of free-radical ring-opening polymerization. While visible-light-cured formulations of the bis(methylene) compounds with methacrylate comonomers did not yield acceptable composite materials in this initial attempt, the high reactivity and the ability to form rigid, cross-linked polymers make this type of monomer worthy of continued investigation. These properties may allow the bis(methylene) oxaspiro monomers to be used alone or in concert with other ring-opening monomers for special applications.

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References

Endo T. , Bailey WJ (1975). Synthesis and radical ring-openingpolymerization of spiro o-carbonates. JPolym Sci, Polym Chem Ed 13:2525-2530.

Feilzer AJ , De Gee AJ , Davidson CL (1987). Setting stress in composite resin in relation to configuration of the restoration. J Dent Res 66:1636-1639.

Feilzer AJ , De Gee AJ , Davidson CL (1990). Quantitative determination of stress reduction by flow in composite restorations. Dent Mater 6:167-171.

Fukuda H. , Hirota M. , Nakashima Y. (1982). Spontaneous copolymerization of 4-methylene-1,3-dioxolanes with maleic anhydride. J Polym Sci Polym Chem Ed 20:1401-1409.

Penn RW ( 1986). A recording dilatometer for measuring polymerization shrinkage. Dent Mater 2:78-79.

Stansbury JW (1988). Free radical ring-opening polymerization of unsaturated, asymmetric spiroorthocarbonates(dissertation). College Park (MD): University of Maryland.

Stansbury JW , Bailey WJ (1986). Synthesis of monomers that polymerize with expansion in volume (abstract). JDent Res 65:219.

Stansbury JW , Bailey WJ ( 1990). Evaluation of spiro orthocarbonate monomers capable of polymerization with expansion as ingredients in dental composite materials . In: Gebelein CG , Dunn RL , editors. Progress in biomedical polymers. New York: Plenum Press, 133-139.

Tagoshi H. , Endo T. ( 1989). Radical polymerization of unsaturated spiroorthocarbonate . JPolym Sci, Polym Chem Ed 27:1415-1418.

10.

Thompson VP , Williams EF , Bailey WJ (1979). Dental resins with reduced shrinkage during hardening . JDent Res 58:1522-1532.

11.

Wang Y. , Pan CY (1990). Synthesis and free radical ring-opening polymerization of 2-alkyl-7-methylene-1,4,6-trioxaspiro[4.4]-nonane. Polym Prep (Am Chem Soc, Div Polym Chem) 31: 661-662.

12.

Zindan 0 , Gomez-Marin 0 , Tsuchiya T. (1987). A comparative study of the effects of dentinal bonding agents and application techniques on marginal gaps in class V cavities . JDent Res 66:716-721.