The temperature and frequency dependence of their dielectric constants have been investigated for two dimers consisting of swallow-tailed terminal groups connected via siloxane central parts of di erent length. The results have been compared with those of the respective monomer. The central part contributes in di erent ways to the static dielectric constants in the isotropic phase. From relaxation measurements, it can be concluded that the reorientation process about the short axis of the terminal groups is comparable with the respective process in monomers. The relaxation frequencies as well as intensities are almost unin¯uenced by the siloxane part which suggests a very¯exible structure of such dimers. Unfortunately, the maintenance of the antiparallel arrangement of swallow-tailed parts of the dimers could not be proved because of insu cient material for experimental work on the SA phase.
Summary: Rod‐like cellulose polymers, with flexible isopentyl side chains, form supramolecular constructs by the Langmuir‐Blodgett (LB) technique. These have been employed to model an ultrathin multilayered primer for surface modification by polymerization. Multilayers of this polymer were doped with a solution of a photosensitizer and then exposed to methyl methacrylate, (MMA) in either the vapor or liquid phase. Polymerization of the monomer swollen construct was induced photochemically. FT‐IR spectra reveal that photoinitiation in presence of the photosensitizer or irradiation in the far UV region induces photografting by hydrogen abstraction from the constituents of the layered assembly. Employing a combination of photoinitiators (benzophenone and 4,4′‐bis(diethylamino)‐benzophenone) and irradiation of the construct that was saturated by monomer from the gas phase in the near UV region caused the formation of a semi‐interpenetrating polymer network. Linear polymer chains of PMMA grow and entangle inside the layered assembly of the cellulose derivative. The resulting composite consists of two polymers, isopentylcellulose and poly(methyl methacrylate) demonstrating a possibility to produce a homogeneous layered composite film at nanoscopic scale as revealed by the X‐ray reflectometry. Surface photopolymerization was also achieved in the liquid phase where the monomer and photoinitiator solution was in direct contact with the layered assembly.Schematic picture of the composite films consisting of multilayered CIPC and PMMA incorporated via vapor phase photopolymerization. The scale of the CIPC hairy‐rods and periodic spacing is only schematically represented.magnified imageSchematic picture of the composite films consisting of multilayered CIPC and PMMA incorporated via vapor phase photopolymerization. The scale of the CIPC hairy‐rods and periodic spacing is only schematically represented.
Different polymers were investigated with respect to the sorption of solvents and gases. Depending on the chemical nature of the polymers this sorption leads to polymer swelling. The degree of swelling D/Do was measured utilizing Small angle X-ray scattering (SAXS) as well as Surface plasmon resonance (SPR). From the change in film thickness after swelling in different solvents Hildebrand parameters of the polymers were determined. By crosslinking of the polymer films the degree of swelling can be controlled. In the case of ultrathin polyimide films a higher degree of crosslinking led to a decreased selectivity of the transport of gases through the membrane. Reptation of macromolecules was also investigated and the influence of polymer swelling in different solvents has a great influence on the selectivity and diffusion coefficient .
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