Stepwise surface modification of mesoporous silica and its use in poly(urethane‐urea) composite films

Abstract

The compatibility between polymer matrix and filler is a vital issue in the fabrication of composites with desirable properties. To enhance the interfacial adhesion between matrix and filler, various surface modification treatments are applied. The objective of this study was to increase the affinity of silica and poly(urethane-urea)s (PUUs), thereby improving the mechanical properties of the resulting composites. Stepwise surface modification of mesoporous silica with amine-containing dendrimers was done. Various techniques were used to confirm the surface-modified structure during the stepwise reaction. Additionally, the N 2 adsorption-desorption method indicated a gradual reduction in surface area, pore diameter and pore volume of the particles, which warrants the gradual propagation of the dendrimers on the surface and also inside the pores. A type IV isotherm was obtained in this analysis. Two types of pre-synthesized PUUs were chosen for composite preparation containing the surfacemodified silica with 0.5, 1, 2.5 and 5 wt% concentrations. Due to the high affinity of the dendrimers containing amine moieties on the particles with polyurethane, a proper dispersion of particles in the matrix was achieved based on scanning electron micrographs. Tensile measurements showed an increased Young's modulus and strength of polyurethane films as a result of addition of the particles. However, no significant improvement in the tensile performance of the composites was seen above 2.5 wt% particle loading due to some particle aggregations.

Synthesis and characterization of surface-modified magnetic mesoporous silicate materials for phosphate adsorption

“…Silica is classified into two categories: nonporous and mesoporous. The main characteristics of mesoporous silica are controlled pore size, narrow distribution of pore size and high specific surface area [ 8 – 10 ]. Dinari and coworkers many times modified ordered mesoporous silica with different groups using different methods, and has been studied in many applications such as adsorbents for trace Cr VI removal [ 11 – 13 ].…”