Authors: J.P. Killgore, R.M. Overney
Affilation: University of Washington, United States
Pages: 908 - 911
Keywords: poly(trimethylsilyl propyne), nanocomposite, silica, membrane, HT-AFM
A novel nanoscale thermomechanical methodology is introduced involving resistively heated cantilevers, also referred to as heated tip AFM (HT-AFM), that provide direct access to the interfacial interaction strength between poly(trimethyl silyl propyne) (PTMSP) - silica nanocomposites. This nanocomposite system has recently been introduced as a new class of reverse selective membranes with extraordinarily high permeability and selectivity (reverse selectivity). Here, we examine the thermal transition properties of the polymer matrix and the debonding strength between PTMSP and silica. Transitions at 330°C were identified as degradation processes. Criteria for debonding were found to include polymer viscoelastic responses, particle size, embedding depth, scan speed and frequency of impact. Employing a torsionally calibrated thermal atomic force microscopy (AFM) cantilever, probe-particle impact forces revealed a debonding energy of 2.6 J/m2 and an impact force transition that occurs 30°C below the degradation temperature in the neat polymer, confirming the presence of enhanced polymer mobility at the PTMSP-silica interface.