Interfacial Mobility and Bonding Strength in Nanocomposite Thin Film Membranes

Abstract

The interfacial interaction strength and transition properties in a reverse selective thin film nanocomposite system, silica-poly[(trimethylsilyl)propyne] (SiO(x)-PTMSP), are investigated locally by heated tip atomic force microscopy. SiO(x)-PTMSP has recently been introduced as a new class of reverse selective membrane materials 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 degrees 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. Probe-particle impact forces revealed a debonding energy of 2.6 J/m(2) and an impact force transition that occurs 30 degrees C below the degradation temperature in the neat polymer, confirming the presence of enhanced polymer mobility at the SiO(x)-PTMSP interface.

Annular Coated Inclusion model and applications for polymer nanocomposites – Part I: Spherical inclusions

“…While efforts to directly characterize the properties of the interphase experimentally are extraordinarily difficult due to the size and nature of the interphase region in nanocomposites, earlier SEM imaging illustrating a significant adsorbed polymer layer on nanotubes protruding from fracture surfaces in a MWNT/polycarbonate system [24] is consistent with the formation of an interphase region in these materials. In addition, experimental work in the thin-film polymer community has shown large differences in 6 polymer-chain mobility and properties resulting from interactions with surfaces (including free surfaces) [25].…”

“…The final boundary condition is that the far-field stresses components (23) Given (21), we can again use standard strain-displacement equations such that the strain components in the inclusion phase can then be written as (24) while the strain components in the interphase can be written as (25) and the strain components in the matrix can be written as (27) Once all the radial strain components are known, the radial stress components of each phase can be readily found using Hooke's Law.…”

Insight into reverse selectivity and relaxation behavior of poly[1-(trimethylsilyl)-1-propyne] by flux-lateral force and intrinsic friction microscopy

“…A solely activated process in a polymer such as PTMSP involves an isolated motional process, which is consistent with side chain rotation, or highly isolated backbone motions [24,27]. As we consider PTMSP in a temperature range far below its decomposition temperature and glass transition of 330 • C [41] we can neglect translational modes of relaxation, which are also known to be highly cooperative [24,25,27].…”

Characterizing the free and surface-coupled vibrations of heated-tip atomic force microscope cantilevers

“…Subsequently, advances in microfabrication led to silicon probes with integrated heaters and tip sharpness comparable to traditional AFM probes [14,15]. Applications of heated-tip AFM (HT-AFM) have included surface manipulation for materials testing [16,17] and data storage [18], as well as local thermal analysis approaches to identify the softening temperature of materials [13,19]. To control the current flow and allow the tip to be heated, the cantilevers exhibit a U-shaped geometry ( figure 1(a)) with a lower-doped region near the free end of the cantilever.…”