Derek B. Schwarz, Kevin A. Cavicchi and James M. Eagan*,
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引用次数: 0
Abstract
Bottlebrush poly(propylene carbonate) (PPC) was synthesized with defined molecular dimensions in order to understand their relationship to viscoelastic properties. Chain-transfer polymerization of propylene oxide with CO2 using a tethered binuclear cobalt(III) salen catalyst afforded norbornene maleimide end-functionalized PPCs that yielded bottlebrush polymers through subsequent ring-opening metathesis polymerization. A series of PPC bottlebrushes were synthesized with varied side-chain (6 < Nsc < 198) and backbone lengths (100 < Nbb < 1,000). Several bottlebrushes were synthesized wherein the maleimide backbone was entangled or unentangled and/or PPC side-chains were entangled as evidenced by the material’s plateau modulus measured by small amplitude oscillatory frequency sweeps. The brushes’ rubbery moduli ranged from 29 to 485 kPa depending on the dimensions and volume fraction of PPC. As the dimensions of the backbone and side-chain were varied, the material densities and plateau moduli were used to calculate the bottlebrush crowding factor in order to demonstrate that the materials behave as backbone-extended bottlebrushes and not as densely grafted combs. The PPC side-chains could be depolymerized through a chain-end backbiting reaction to yield propylene carbonate or thermally cross-linked through transcarbonation reactions of the side-chains.
期刊介绍:
Macromolecules publishes original, fundamental, and impactful research on all aspects of polymer science. Topics of interest include synthesis (e.g., controlled polymerizations, polymerization catalysis, post polymerization modification, new monomer structures and polymer architectures, and polymerization mechanisms/kinetics analysis); phase behavior, thermodynamics, dynamic, and ordering/disordering phenomena (e.g., self-assembly, gelation, crystallization, solution/melt/solid-state characteristics); structure and properties (e.g., mechanical and rheological properties, surface/interfacial characteristics, electronic and transport properties); new state of the art characterization (e.g., spectroscopy, scattering, microscopy, rheology), simulation (e.g., Monte Carlo, molecular dynamics, multi-scale/coarse-grained modeling), and theoretical methods. Renewable/sustainable polymers, polymer networks, responsive polymers, electro-, magneto- and opto-active macromolecules, inorganic polymers, charge-transporting polymers (ion-containing, semiconducting, and conducting), nanostructured polymers, and polymer composites are also of interest. Typical papers published in Macromolecules showcase important and innovative concepts, experimental methods/observations, and theoretical/computational approaches that demonstrate a fundamental advance in the understanding of polymers.