Effects of surface modification of glass beads with poly(acrylic acid)

Abstract

Etched glass beads were functionalized with 3-aminopropyltriethoxysilane (APS) and glycidoxypropyltrimethoxysilane (GPS). The surface of glass beads were further modified with poly(acrylic acid) by reacting the carboxyl groups on poly(acrylic acid) with the amino groups of the grafted aminopropyltriethoxysilane. The modifications were characterized by FT-IR spectroscopy and tensiometry for contact angle and porosity measurements. Five different molecular weight PAA polymers ranging from 2,000 to 3,000,000 were grafted with less than expected increase of grafting% with molecular weight. The amount of poly(acrylic acid) (PAA) on the surface was determined from thermal gravimetric analysis and elemental analysis data. The surface properties of surface modified glass beads were determined by measuring water and hexane penetration rate and contact angle. The surface morphology was examined by scanning electron microscopy.