Two water-soluble polymers poly(2-methyl-2-oxazoline) and poly(N-isopropylacrylamide) with complexing moieties (β-CD and adamantane, respectively) located at the chain ends were prepared via controlled techniques. To verify the interaction of the β-CD- and adamantane-type polymer end groups in aqueous solution, detailed complexation studies were carried out by 1H NMR spectroscopy. It could be proved, that the polymers undergo self-assembly to form the corresponding supramolecular diblock structure. Furthermore, the double-hydrophilic block assembly was observed to be switchable to a hydrophilic−hydrophobic configuration by adjusting temperature leading to reversible aggregate formation.
Summary: Several functionalized block copolymers based on polystyrene with considerably different block polarities have been prepared using controlled radical polymerization techniques (NMRP, RAFT). The target polymers, having hydroxy, alkyne or amine functionalities in at least one block were characterized by techniques like NMR, GPC and DSC to verify structure, molar masses, molecular weight distributions and thermal properties. With the example of partly protected hydroxystyrene based block copolymers, regular structured film surfaces could be created and were shown to be converted into homogeneous polymer surfaces by applying heat as external trigger. With alkyne functionalized block copolymers, modifications with objects of varying sizes were carried out, employing the 1,3-dipolar cycloaddition of alkynes with azides. Once again, the ''click approach'' proved its high efficiency as the reactions proceeded completely even with objects of high steric demand. Studying the influence on the macromolecular architecture, we found a strong alteration of glass transition temperatures for the compared polymer materials, indicating a bracing of the chains due to steric hindrance between the bulky side objects.
Two phase separating block copolymers with photolabile protected amino groups in one block have been synthesized through RAFT polymerization followed by efficient click modification. Techniques like NMR, GPC, and DSC were applied for the characterization of these functional materials. The block copolymers were used for the preparation of thin films where they assemble to form distinct nanostructures as detected by AFM analysis.
Summary: Total internal reflection ellipsometry (TIRE) under surface plasmon resonance (SPR) conditions represents a powerful characterization technique combining the conveniences of spectroscopic ellipsometry with SPR. Besides the very high sensitivity to small changes in the optical constants (up to 10 times more sensitive than conventional ellipsometry), the possibility to investigate media of different optical densities or even opaque media makes this analytical method very convenient for different sensing applications. This article presents an example of application of TIRE under SPR conditions for the continuously in-situ monitoring of the growth of covalently tethered poly(N-isopropylacrylamide) (PNIPAAm) chains on a gold surface.
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