An Atomic Force Microscopy Study of the Interactions Involving Polymers and Silane Networks

Abstract

Silane coupling agents have been frequently used as interfacial agents in polymer composites to improve interfacial strength and resistance to fluid migration. Although the capability of these agents in improving properties and performance of composites has been reported, there are still many uncertainties regarding the processing-structure-property relationships and the mechanisms of coupling developed by silane agents. In this work, an Atomic Force Microscope (AFM) was used to measure interactions between polymers and silica substrates, where silane networks with a series of different structures were processed. The influence of the structure of silane networks on the interactions with polymers was studied and used to determine the mechanisms involved in the coupling phenomenon. The AFM results showed that phenomena such as chain penetration, entanglements, intersegment bonding, chain conformation in the vicinities of rigid surfaces were identified as being relevant for the overall processes of adhesion and adsorption of polymeric chains within a silane network. AFM adhesion curves showed that penetration of polymeric chains through a more open silane network can lead to higher levels of interactions between polymer and silane agents.

Evaluation of the interactions between polymeric chains and surfaces with different structures performed by an atomic force microscope

“…In this scenario, the polymer chains are being brought continuously in and out of contact with the surface. This cyclic mechanism mimics 24 Oréfice & Brennan Materials Research Figure 6. AFM tip preparation and measurements.…”

“…1. The NMR study 24 also demonstrated that the substitution occurs preferentially on the ortho position, in relation to the ether group, of benzene rings at the Bisphenol A unit ( Fig. 1).…”

“…9. This type of mechanism is used to explain adhesion between polymer chains and silane coated reinforcing agents in polymer composites 24,25,26 .…”

“…The height of the 1028 cm -1 peaks was then ratioed against the 1010 cm -1 peaks. The degree of substitution of a specific sulfonated polysulfone was calculated using NMR data published in another manuscript 24 . This value was used to calibrate the FTIR data of polymers with different degrees of substitution, by associating it to the FTIR peak ratio of the same polymer.…”