Solvent-free reversible deactivation radical polymerization of myrcene, a naturally occurring terpenoid monomer, with high regioselectivity was developed recently. Here, this green polymerization system is further improved to reach increased yields and produce polymers with high molar mass but still low dispersity and regioregular microstructure. To this end, two initiators (dibenzoyl peroxide, DBPO; azobis(isobutyronitrile), AIBN) at 65, 90, and 130 °C were applied, and it was demonstrated that these varying conditions have a huge effect not only on the monomer conversion and the molar mass of the product, but also on the microstructure of the resulting polymyrcene. The polymerizations utilized two trithiocarbonate chain-transfer agents, and were similar in yields, molar masses, and dispersity of the produced polymyrcene, but progressed differently for the diverse initiator–temperature pairs. Generally, in all systems, pseudo-first-order kinetics, linear increase of molar mass with conversion, and low Đ values were found as a result of controlled polymerization. The systems using AIBN and DBPO initiators at 90 and 130 °C, respectively, have rate constants of propagation (k p app) lower than the decomposition rates (k d) of initiators, likewise important to control the polymerizations. At 130 °C, also branching occurred at the higher stage of the reaction, and lower regioregularity developed during the polymerization as a consequence of the favorable junction formation at elevated temperature and increased viscosity. Generally, compared to the previous study on the reversible deactivation radical polymerization of myrcene via reversible addition–fragmentation chain-transfer polymerization process, significantly higher conversions (30 → 65%) and increased chain length (9 → 40 kDa) were reached. The dispersity values for these polymerizations remained as low as 1.3–1.6, and also regioregular microstructures (up to 94%) were detected.
Water-soluble shape-persistent cyclodextrin (CD) polymers with amino-functionalized end groups were prepared starting from diacetylene-modified cyclodextrin monomers by a combined Glaser coupling/click chemistry approach. Structural perfection of the neutral CD polymers and inclusion complex formation with ditopic and monotopic guest molecules were proven by MALDI–TOF and UV–vis measurements. Small-angle neutron and X-ray (SANS/SAXS) scattering experiments confirm the stiffness of the polymer chains with an apparent contour length of about 130 Å. Surface modification of planar silicon wafers as well as AFM tips was realized by covalent bound formation between the terminal amino groups of the CD polymer and a reactive isothiocyanate–silane monolayer. Atomic force measurements of CD polymer decorated surfaces show enhanced supramolecular interaction energies which can be attributed to multiple inclusion complexes based on the rigidity of the polymer backbone and the regular configuration of the CD moieties. Depending on the geometrical configuration of attachment anisotropic adhesion characteristics of the polymer system can be distinguished between a peeling and a shearing mechanism.
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