Polymers with carboxylic acid functionalities are widely used in adhesives, absorbents, dispersants, drug delivery systems, and hydrogels. Unlike common radical polymerization, it is difficult to synthesize polymers with carboxylic acid groups via anionic ring-opening polymerization because of the harsh reaction conditions. Although a carboxylic acid-functionalized polyether, poly(glycidoxy acetic acid), was previously prepared by using monomer-activated ring-opening polymerization, this approach often suffers from a low initiation efficiency and is limited to homopolymerization. Herein, we present a novel functional epoxide monomer bearing oxazoline as a protecting group, 4,4-dimethyl-2-oxazoline glycidyl ether, for a controlled synthesis of poly(4,4-dimethyl-2-oxazoline glycidyl ether) by overcoming the aforementioned limitations. The stepwise syntheses of the monomer and polymers were carefully analyzed via 1 H NMR, GPC, FT-IR spectroscopy, and MALDI-ToF analysis. Furthermore, copolymerization with another monomer and a macroinitiator yielded well-defined polymers. We anticipate that this study will provide a new platform for the synthesis of polyethers with carboxylic acid functional groups.

The chemical synthesis of degradable poly(β-hydroxyalkanoate) (PHA) produced by microorganisms allows the control of the solubility, crystallinity, hydrophobicity, degradability, thermal, and mechanical properties by introducing functionality on the side chain. Herein, we synthesized a PHA derivative containing a pendant allyl group via the anionic ring-opening polymerization of a 4-allyloxymethyl-β-propiolactone (AMPL) monomer, which was prepared via the carbonylation of allyl glycidyl ether. The AMPL monomer was subjected to various organocatalysts in bulk to yield poly(4-allyloxymethyl-β-propiolactone) (PAMPL) with controllable molecular weight and dispersity. The prepared PAMPL polymers were characterized via 1 H and 13 C NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and matrix-assisted laser desorption/ ionization-time-of-flight (MALDI-TOF) analyses. A photoactivated thiol−ene reaction allowed the postpolymerization modification of PAMPLs with varying substituents. Functionalized PAMPL polymers degraded under chemical and thermal conditions, and importantly, cross-linked PAMPL films degraded during exposure to soil and seawater under a wide range of degradation kinetics. This study provides the future potentials of the chemically synthesized and functionalized PHA for replacing conventional petroleum-derived polymers.

A simple and divergent synthetic strategy of bottlebrush polymers (BBPs) is presented, consisting of postpolymerization modification of a macromonomer and grafting-through polymerization. Beginning with a single macromonomer, its direct modification could build a library of macromonomers with an identical chain length, thus guaranteeing the precision in the synthesis of BBPs. In this study, a newly designed norbornenyl-terminated poly(methyl acrylate) (NB-PMA) is proposed as a chemically robust template. Ti-mediated transesterification of NB-PMA successfully produces structurally diverse polyacrylates while maintaining the terminal norbornenyl group intact. All macromonomers obtained from transesterification possess a good grafting-through ring-opening metathesis polymerization reactivity, furnishing homo, random, and block BBPs in a controllable manner. Moreover, atomic force microscopy analysis supports the controlled side-chain length distribution in the resulting BBPs.

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