Surface dissolution and transesterification of thermoset dimethacrylate polymer by dimethacrylate adhesive resin and organic catalyst-alcohol solution.

OBJECTIVES

To evaluate transesterification based dissolution of dimethacrylate and epoxy polymers, the former containing ester groups. Polymer substrates were treated with an adhesive resin (Stick™ Resin) and an organic catalyst-alcohol solution (ethylene glycol and triazabicyclodecene). The surface was chemically and nanomechanically analyzed with Fourier Transform-Infrared (FTIR) spectroscopy, surface profile peak (R) and nanohardness and modulus of elasticity.

METHODS

A total of 100 specimens each of light-cured dimethacrylate polymer and heat-cured diepoxy polymer were prepared. 20 specimens were randomly selected and used as control group (0s). The remaining specimens were randomly divided into 40 each for treatment with an Stick™ resin and ethylene glycol+triazabicyclodecene. Within each group the 40 specimens were randomly subdivided into 20 each for treatment at 5min and 24h, with 10 specimens for FTIR and nanohardness and modulus of elasticity, and the other 10 for SEM and surface R analyses.

RESULTS

Dimethacrylate polymer showed a reduction in the nanohardness and modulus of elasticity, R values and SEM also showed significant topographical changes after being treated with either Stick™ resin or ethylene glycol+triazabicyclodecene, whereas epoxy resin substrate did not. FTIR analyses affirmed changes in the intensity of ester groups.

SIGNIFICANCE

Ester group containing dimethacrylate polymer showed a reduction in NMP within 5min of exposure to the treatment agents with softening by solution ethylene glycol+triazabicyclodecene associated to the reduction of ester groups in the polymer structure by transesterification. Epoxy polymer without ester groups was not affected by surface softening with treatment agents. Adhesive resin caused surface swelling.