The primary objective of the study is to investigate the impact of chemical structure at the interface on the interface strength of fiber/matrix composite. A solvent based method was used to deposit trichlorosilane on E-glass fiber surfaces followed by in situ modification of the deposited layer to prepare pure and mixed amine undecyl self assembled monolayer (SAM). The extent of fiber/matrix adhesion was determined by performing single fiber fragmentation test (SFFT). The SFFT data indicate that ≈ 85 % of fiber breaks obtained for epoxy composite occurs at a much lower mass fraction of amine coverage for SAM while a similar number of fiber breaks occur at a much higher mass fraction of amine coverage for aqueous solution deposited coupling agent system.