Schuh1 and co-workers have recently reported on a general procedure for preparing robust multilayered polymer structures using C-H insertion reactions. Designed polymer multilayers can be prepared from sequential steps of spincoating followed by thermal or photochemical crosslinking steps. This approach is comparable to layer by layer deposition or Langmuir Blodgett methods in that multilayers are formed but should generalize the preparation of such structures to the set of polymers containing C-H bonds. The crosslinking approach has the advantage that chemical bonds are formed across the interfaces leading to superior adhesion between layers. In the current study we have prepared thin multilayer films containing pendant benzophenone moieties with layers that are alternately hydrophilic or hydrophobic. The benzophenone groups are capable of UV activated crosslinking. Neutron reflectivity was used to study the importance of crosslinking to interlayer mixing. In order to generate contrast between layers, a PMMA copolymer was prepared from deuterated (d8) MMA monomer and 5% comonomer containing the benzophenone photocrosslinker. The hydrophilic polymers were selected from a series of copolymers containing dimethylacrylamide, acrylic acid and the benzophenone crosslinking moiety. Multilayers were prepared on thick silicon wafers by application of ca. 1 mg ml-1 solutions of polymer and thicknesses checked by ellipsometry. Film robustness was demonstrated as films could be removed by simply spinning the wafer with solvent prior to UV exposure. After UV exposure, multiple attempts to remove the layers in this manner were unsuccessful. Neutron reflectivity experiments were performed at NIST on the NG7 beamline. 1. Schuh, K., Prucker, O. and Rühe, J. (2013), Tailor-Made Polymer Multilayers. Adv. Funct. Mater., 23: 6019–6023. doi: 10.1002/adfm.201300846

Neutron reflectivity studies of polymer multilayers prepared by sequential spin coating

251st National Meeting (2016)

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