Enhanced Hydrophobicity of PMMA via Bulk Copolymerization with a Bulky Siloxane Methacrylate Monomer

Abstract

Poly(methyl methacrylate) (PMMA), also known as acrylic glass, is widely used for its excellent light transmittance but suffers from poor hydrophobicity. To improve this, this paper proposes a streamlined, one-step modification process via bulk polymerization. Methacryloxypropyl tris(trimethylsiloxy)silane (TRIS) was synthesized and then copolymerized with methyl methacrylate (MMA), producing a hydrophobically modified acrylic material. Adding TRIS significantly increased the surface hydrophobicity of PMMA. With a 1.8 wt % TRIS mass fraction, the water contact angle reached about 90°, and the transmittance remained above 91%, though it was slightly reduced. Unlike traditional surface coating, bulk copolymerization forms a chemical bond between TRIS and MMA, modifying the molecular structure throughout the material. The modified material’s hardness, bending, tensile, and impact properties remained similar to pure PMMA. Incorporating the silicone monomer also reduced dielectric properties and improved thermal resistance.