Nontraditional polyurethane (PU) has been successfully synthesized by anionic copolymerization of some typical aryl isocyanates and epoxides with ammonium halide onium salt (Lewis base) as the initiator and triisobutylaluminum (Lewis acid) as the activator and the synergistic coordinator. In contrast to the traditional step-growth approach, this chain-growth copolymerization can maintain the anionic propagation site and exhibit some living features with a high activity, by which the copolymers synthesized have narrow molecular weight distributions and discrete end groups. The copolymer is primarily constituted by a urethane linkage, and the byproducts of isocyanurate trimer and oxazolidinone can be effectively suppressed as the polymerization proceeds. Density functional theory (DFT) calculations were also performed to support the proposed reaction mechanism.

A class of polymer-in-salt electrolytes (PISEs) based on cross-linkable polyethers bearing pendant cyclic carbonate groups has been developed. This type of cyclic carbonate substituted polyether has a low glass transition temperature and shows good chemical and electrochemical stability. We have revealed the effects of the spacer length and the backbone on the ion conduction in detail. The PISE with a moderate interaction between polymer segments and lithium ions exhibits a higher ionic conductivity, and a nearly 3-fold increase in lithium ion transference number compared to that of conventional salt-in-polymer electrolytes. With a high concentration of salt, the growth of dendrites from the lithium–metal anode can be effectively suppressed and a uniform lithium deposition has been observed, which has been related to the formation of the inorganic-rich solid electrolyte interphase. Moreover, the in situ cross-linking of the PISE gives rise to a flexible yet mechanically robust elastomeric thin film with a fast lithium ion conduction, which eventually enables the good-performance all-solid-state Li/LiFePO4 batteries with high cycling stability and Coulombic efficiency at ambient conditions. This work is anticipated to advance the research of PISEs for potential applications in high-energy lithium metal batteries.

A class of heteroatom polymers through anionic chain growth copolymerization of epoxides and isothiocyanates has been successfully obtained under mild conditions via initiation by a simple salt of lithium alkoxide. The resulting polymers have characteristics of controlled molecular weights and low dispersity with a well-defined backbone of carbonimidothioate repeat units (-OC­(=N)­S-) at 100% alternating degree, which have been confirmed in the 1H-13C heteronuclear multiple bond correlation NMR spectrum and mass spectrum. Side reactions have been greatly suppressed in the copolymerization, and no more than 5% cyclic small molecular byproducts have been produced. We have revealed the special role of lithium bonds in regulating the alternating copolymerization of these two types of monomers, which are involved in activating isothiocyanates as well as binding the incoming monomers to the growing chain ends due to the especial coordination capability of lithium ions to multiple nucleophilic sites. The proposed mechanism of the alternating copolymerization process is supported by density functional theory calculations. Moreover, the copolymerization exhibits first-order kinetics with respect to the monomers and a quasi-living feature. Our strategy is expected to shed light on the incorporation of different types of cumulated double bonds as comonomers into polymer backbones, and the high availability of epoxides and isothiocyanates of various substitutions will forge the development of such kinds of heteropolymers.

A copolymer flocculant (CATCS) derived from starch and chitosan was fabricated and used as eco‐friendly adsorbent for removal of Cr(VI) from aqueous solution. The CATCS flocculant was characterized by scanning electron microscope, thermogravimetic analysis, and Fourier transform infrared spectroscopy. The effects of CATCS dosage, initial Cr(VI) concentration, pH, and reaction time on removal of Cr(VI) were discussed. The results showed CATCS removed Cr(VI) effectively and the adsorption isotherm agreed well with the Freundlich isotherm and R–P isotherm models. The enthalpy change (ΔH) of the process was 16.75 kJ/mol suggesting the existence of chemisorption and the reaction was endothermic. Moreover, the negative free energy change (ΔG) indicated the adsorption process was feasible and spontaneous. The positive entropy change (ΔS) showed there was an increase of disorder in the system during the adsorption process. The adsorption kinetics results showed that the adsorption could be described by the pseudo‐second‐order kinetics mechanism. The activation energy (Ea) of the adsorption reaction was 29.16 kJ/mol. POLYM. ENG. SCI., 56:1213–1220, 2016. © 2016 Society of Plastics Engineers

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