A General Strategy for Adhesion Enhancement in Polymeric Composites by Formation of Nanostructured Particle Surfaces

Abstract

In this work we present a general methodology to enhance the interfacial adhesion in polymeric composites by creating nanoscale morphologies on the surfaces of particles. The surface morphology, which appears as inorganic whiskers, is achieved by treating silicate particles (zeolites 4A) with thionyl chloride, followed by subsequent reaction with methylmagnesium bromide (Grignard reagent). Poly(vinyl acetate) and Ultem composites containing this type of modified particles exhibit defect-free interfaces. Dynamic mechanical analysis testing reveals that such composites have higher moduli as compared to those embedded with nontreated fillers with the same loadings. Furthermore, gas permeation measurements demonstrate that these materials also show impressive enhancements in gas separation efficiency. The dramatic increase in the topological roughness (physical heterogeneity) on the sieve surfaces is proposed to provide improved interaction at the interface via thermodynamically induced adsorption and physical interlocking of polymer chains in the nanoscopic inorganic whisker structure. The presented strategy need not be tailored to a specific polymer/filler pair and therefore has potential to be extended to many other polymeric composites for a variety of applications, where tailoring polymer/solid interface compatibility is important.

Polymeric mixed matrix membranes containing zeolites as a filler for gas separation applications: A review

“…A new strategy to promote the interfacial adhesion in polymer/ silicate composites by creating nanoscale morphology is Grignard treatment. Remarkable changes have been observed in gas transport properties of composite films using the modified particles with nanostructured surface morphology [129].…”

“…This method employs a Grignard treatment (GT) method to modify the zeolite surface [128][129][130] and to improve the interfacial adhesion between the zeolite and polymer, the most widespread limitation facing mixed matrix application. The Grignard treatment involves growing Mg(OH) 2 whiskers on the surface, consisting of two steps: (i) a crystal seeding step and (ii) the crystal growth step [131,132].…”

“…A thermodynamic argument was proposed to qualitatively explain why such nanoscale structures contribute to improved adhesion at the interfaces. A surface roughening effect has presumably contributed to the enhancement via thermodynamically induced adsorption and physical interlocking in the whisker structure [93,129,132].…”

Enhanced pervaporation performance of MIL-101 (Cr) filled polysiloxane hybrid membranes in desulfurization of model gasoline

“…Hybrid membranes with inorganic fillers often suffer from the incompatibility between the polymer matrix and the fillers, thus further modification is often required to avert the non-selective voids generated at the interface between the matrix and the fillers (Ahn et al, 2008;Shu et al, 2007;Sun et al, 2008). Organic fillers are preferred choices in terms of compatibility with polymers, but few of them have regular channel structure (Kittur et al, 2005) that can enhance the transport of the penetrant molecules effectively.…”

Highly Conductive Polyfuran-13X Zeolite-Polyaniline Composite

“…First, a good cementation of PANI moieties with PF-13X composites (see SEM images, compared to other PANI reinforced composite systems, a more uniform morphological pattern was obtained for the PANI-PF-13X composite. Secondly it could be due to 'entropy activation,' 31 i.e., polymerization of ANI took place on a more heterogeneous (less order, more entropy) PF-13X composite surface leading to a better distribution of PANI moieties (ordered, less entropy) over the whole system (more coverage). Figure 3 represents dc conductivity values of PANI-PF-13X composite as a function of PANI loading (a) and temperature (b).…”