Influence of different concentrations of an iodonium salt on properties of amine-free resins

Abstract

Objectives: to evaluate the effect of different concentrations of an iodonium salt on the degree of conversion, polymerisation rate, flexural strength and modulus of an amine-free photopolymerizable resin system.

Methods: Two series of UDMA/TEGDMA resin mixtures (1:1 mass ratio) containing 0, 0.5, 1.0 or 2.0 mol% of bis(4-methyl phenyl)iodonium hexafluorophosphate(BPI): and 1 mol% camphorquinone (CQ) were evaluated. One of the series contained 2 mol% of the amine (2-(dimethylamino)ethyl methacrylate-DMAEMA), while the other series had only CQ and BPI as photoinitiators. Polymerisation kinetics and degree of conversion (DC) were evaluated by Fourier transform near-infrared spectroscopy (n = 3). Flexural strength (FS) and modulus (E) were evaluated by a three-point bending method (n = 12). Data were analysed by two-way ANOVA and Tukey's test.

Results: The system containing CQ + DMAEMA + BPI provided the highest DC and FS. Amine-free resins had similar E regardless of the presence of BPI. The resins containing CQ+DMAEMA with 1 and 2 mol% of BPI presented higher E compared with others.

Significance: Amine-containing resins reached statistically higher DC, rate of polymerisation and FS than amine-free systems. The use of higher BPI concentrations did not improve the properties of amine-free resins.

Keywords: Amine; Degree of conversion; Mechanical properties; Polymerisation.