Effects of water on the long-term properties of Bis-GMA and silylated-(Bis-GMA) polymers

Bis-GMA (2,2-bis-[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane) is a viscous hygroscopic monomer which is used with triethyleneglycol-dimethacrylate (TEGDMA) for dental restorations. Bis-GMA was silylated with dimethyl-isopropyl-siloxane and further polymerized in order to increase water resist...

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Bibliographic Details
Published in:Journal of applied polymer science 2008-01, Vol.107 (2), p.1169-1178
Main Authors: Rivera-Torres, Filiberto, Vera-Graziano, Ricardo
Format: Article
Language:English
Subjects:
Applied sciences
Biological and medical sciences
dental polymers
diffusion
Exact sciences and technology
functionalization of polymers
hydrophilic polymers
Medical sciences
Physicochemistry of polymers
Polymerization
Polymers and radiations
surfaces
Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases
Technology. Biomaterials. Equipments
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Summary:Bis-GMA (2,2-bis-[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane) is a viscous hygroscopic monomer which is used with triethyleneglycol-dimethacrylate (TEGDMA) for dental restorations. Bis-GMA was silylated with dimethyl-isopropyl-siloxane and further polymerized in order to increase water resistance and viscosity. The viscosity of the silylated monomer, Sil·Bis-GMA, was 50 times lower than that of the parent monomer. After 1 month in water, poly(Bis-GMA/TEGDMA) absorbed 2.6% water and the silylated polymer, poly(Sil·Bis-GMA), only 0.56%. During this process water extracted residual monomer from each polymer. The behavior of water sorption and desorption as a function of time in poly(Sil·Bis-GMA) was completely different from that shown by poly(Bis-GMA/TEGDMA). The difference is discussed in terms of diffusion coefficients. Initially, water advancing contact angles (θADV) were 75° and 95°, respectively. After 1 month in water both polymers showed a reduction of about 20° in θADV. In poly(Bis-GMA/TEGDMA), the reduction in θADV obey to water absorption and bulk plasticization; it showed a reduction of 15°C in glass transition temperature, Tg. In contrast, the reduction in θADV in poly (Sil·Bis-GMA) obeyed to water adsorption and reorientation of the molecules at the surface in contact with the water phase; it only showed a change of 2°C in Tg. Contact angle hysteresis provided further evidence about plasticization. According to our results poly(Sil·Bis-GMA) is more stable in water than poly(Bis-GMA/TEGDMA). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
ISSN:0021-8995
1097-4628
DOI:10.1002/app.27181