The interface between polymeric and inorganic materials is important to a variety of technologies such as dielectric films, paints, adhesives and composites. In many cases the adhesion between such dissimilar materials determines the quality of the technology itself. Adhesion promoters, such as silane coupling agents or end-grafted homopolymers, can be used to improve adhesion. In our research, we explore an alternative route based on block copolymers (BCP) that anchor to the substrate by one block while entangling with the coating polymer by the other block. The effectiveness will mainly depend on the distribution and amount of adsorbed chains, the strength of anchoring, and how well they entangle with the matrix polymer. We are preforming a systematic series of BCP adsorption studies aimed at manipulating the interfacial properties in order to promote thin film stability and adhesion.

To date, we have studied the effect of matrix molecular weight on the interfacial excess (z*), layer thickness, and layer/matrix interfacial width [Oslanec PRE]. A model system for the adsorbing and matrix species was chosen as poly (deuterated styrene-block-methyl methacrylate) (dPS-b-PMMA) and polystyrene (PS), respectively. An SCMF model of block copolymer adsorption was developed and found to be in qualitative agreement with experimental results. In a subsequent study, the matrix species,PBrxS was varied in order to study how an unfavorable matrix/dPS interaction would influence the interfacial properties. In the one-phase region, z* slightly decreases as x, the bromostyrene content, increases as shown in the figure. Using an SCMF model which includes a small matrix-substrate attraction was found to account for the decrease in adsorbed dPS-b-PMMA. Upon entering the two-phase region, z* increases strongly. Interpretation of this observation is under investigation.