The role of the terminal functional group of self-assembled monolayers on fiber matrix adhesion

Adhesion at the fiber‐matrix interface of a composite is often influenced by a combination of factors such as mechanical interlocking, physicochemical interactions, and chemical bonding in the fiber‐matrix interphase region. We demonstrate the use of an approach using self‐assembled monolayers (SAMs) for studying the impact of one of the factors, chemical bonding, on the overall adhesion of the glass‐fiber/matrix interface. Transformation of these monolayer surfaces using conventional chemistry with a focus on the creation of a terminal functional group that interacts with epoxy resin is reported. The modified surfaces were characterized by ellipsometry, X‐ray photoelectron spectroscopy, and contact angle techniques for chlorosilane coverage, and in situ conversion. The adhesion of diglycidyl ether of bisphenol‐A resin to modified SAMs on E‐glass fibers was measured by performing single‐fiber fragmentation test. The extent of adhesion between the fiber and matrix was found to be dependent on the type of functional group at the terminal end of the SAM in contact with the epoxy matrix. Methyl terminal group resulted in the least adhesion, while amine terminal groups resulted in the most adhesion. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007