Fabrication pentablock copolymer/silica hybrids as self-assembly coatings

Abstract

Novel organic/inorganic hybrid for coating material is prepared by the pentablock copolymer PDMS-b-(PMMA-b-PMPS)2 (PMMDMM) and SiO2 nanoparticles. PMMDMM is obtained via atom transfer radical polymerization (ATRP) by using polydimethylsiloxane (PDMS) as bifunctional macroinitiator. Poly 3-(trimethoxysilyl)propyl methacrylate (PMPS) is designed as the end block for facilitating the chemical bond of triethoxysilane (Si(OCH3)3) groups with SiO2 nanoparticles produced by tetraethyl orthosilicate (TEOS), and poly (methyl methacrylate) (PMMA) is designed as the middle block for improving the solubility and the film-forming ability of copolymer. The homogeneous dispersion of SiO2 nanoparticles in the pentablock copolymer matrix enables PMMDMM/SiO2 to self-assemble into 210nm SiO2 core/PMMDMM shell elliptic or spherical micelles in tetrahydrofuran (THF) solution. This self-assembled aggregate could provide the film surface with uniform distribution of SiO2 nanoparticles, obvious hydrophobicity (101–102° water contact angles), lower surface free energy (22.3–21.8nN/m) and lower viscoelasticity. SiO2 involved into the copolymer matrix could increase the nanostructures roughness. When TEOS is controlled as 20wt.%, the hybrid performs higher glass transition temperature (Tg=113°C) and excellent thermostability (520°C) than PMMDMM (Tg=87°C, 295°C) due to the introduction of SiO2 nanoparticles. These excellent properties promise PMMDMM/SiO2 hybrid as the candidate for coating material.