Mechanical Properties of Poly(alkyl a-fluoroacrylate)s as Denture-base Materials

Abstract

a-Fluoro-substituted acryl polymers, poly(methyl a-fluoroacrylate) (PMFA) and poly(2,2,2,-trifluoroethyl α-fluoroacrylate) (P3FFA) were investigated for extension to denture-base resins. PMFA, in which fluorine attaches to the polymer chain, had excellent mechanical properties: For instance, compressive and bending strength and bending modulus were 50% higher than those of PMMA. P3FFA, in which fluorines are substituted at the end of the pendant alkyl ester, showed poor mechanical properties. Contrary to expectations, the amount of water sorption of PMFA was about twice that of PMMA, while that of P3FFA was almost zero. Copolymers of MFA and 3FFA were prepared in an attempt to optimize the mechanical properties and the water sorption. The copolymer with 40% of 3FFA showed higher compressive, diametral tensile, and bending strength; in particular, the bending modulus and water resistance were about 35% and 20% higher, respectively, than those of PMMA. Improvement of the mechanical properties and increase of the water sorption of PMFA may be due to intermolecular forces induced by polarizability of the fluorine and carboxy group along the polymer chain. Decrease of the water sorption by fluorine substituted on the alkylester group as in P3FFA may be due to higher hydrophobicity and steric ejj"ect of the fluoroalkyl substitute.