Front Cover: Polymers cured by free-radical/cationic ring-opening hybrid polymerization under visible-light irradiation are studied to determine the effects of photo-polymerization kinetics and chemical miscibility on their crosslinking structure and mechanical properties. The chain transfer reaction between the epoxy group of the epoxide and the hydroxyl group of the methacrylate plays an important role in the formation of the crosslinking network, not only enhancing the crosslinking density, but also preventing the micro-sized phase separation. Further details can be found in the article by X. Ge, Q. Ye,* L. Song, A. Misra, and P. Spencer* on page 856.

Metal-free click polymerization (MFCP) has been developed to circumvent the problems inherent in the broadly-applied Cu(I)-catalyzed azide-alkyne click polymerization reactions. The regioselective MFCP of azides and alkynes to produce regioregular polytriazoles is summarized, and the properties and applications of the resultant polymers are also discussed.

A novel donor–acceptor electrochromic material (poly-3HTP) containing a pyrene subunit is directly deposited onto an indium tin oxide (ITO)/glass surface via an electrochemical process. The polymer film exhibits a multielectrochromic feature, a strong near-infrared absorption at the oxidized state with an optical contrast of 88% (at 1800 nm), a very fast response time of 0.5 s and fast switching times, and long-term stability.

Diblock/triblock copolymer mixtures consisting of polylactide and poly(ethylene glycol) blocks form “sunflower-type” micelle particles in aqueous media with furanyl groups on the corona terminals. A mixed micelle solution of the enantiomeric copolymer mixtures undergoes a sol–gel transition, which is affected by the diblock/triblock copolymer ratio.

Joint experimental and computational methods are used to study the hexagonal boron nitride (h-BN) exfoliation behavior in h-BN/PE composite fibers during hot-drawing. Experimental evidence suggests a polymer-assisted exfoliation process of h-BN under the drawing conditions, which is then morphologically confirmed and statistically analyzed using molecular dynamics simulation.

The effects of polymerization kinetics and chemical miscibility on the crosslinking structure and mechanical properties of polymers cured by visible-light initiated free-radical/cationic ring-opening hybrid photopolymerization are studied. The results support the important role that the chain transfer reaction between the epoxy and hydroxyl groups of methacrylate plays in the formation of the crosslinking network. The chain transfer reaction not only enhances the crosslinking density, but also prevents microphase separation.

The self-assembly behavior of amphiphilic copolymers containing cationic ethylene imine, neutral hydrophilic 2-methyl-2-oxazoline, and hydrophobic 2-phenyl-2-oxazoline segments (HMPOx copolymers) in aqueous media and their complexation with DNA is investigated. The results are expected to have valuable implications for future utilization of these copolymers as nanocarriers of compounds of therapeutic interest.

A mathematical model for the mini­emulsion polymerization initiated by oil-soluble initiators is described to compare with the experiment results, which puts an end to the debate that the effective radicals for the polymerization are originated from the primary radicals desorbed from the particles.

A monomer-free atom-transfer radical polymerization (ATRP) model system is studied in aqueous solution via on-line vis–NIR spectroscopy, with CuBr/2,2′-bipyridine as the catalyst. Addition of NaBr avoids water-assisted dissociation of the Br–Cu(II)/L bond. The ATRP activation–deactivation equilibrium constant and the activation rate coefficient increase significantly with water content.

The instantaneous rate of gas-phase ethylene polymerization is promoted in presence of a variety of commonly used induced condensing agents (ICAs). This is attributed to the effect of the ICA compound in enhancing the local concentration of ethylene at the active poly­merization sites dispersed through the growing polymer particles.

A simple strategy of remodeling of polymer networks and the subsequent crosslinking process (RsC process) is proposed, for preparation of uniform alginate microbeads with ultrahigh density, up to ≈38 wt%, via size reduction to 34% of the initial size. Such microbeads could be applied to prepare various alginate hydrogels of high density, with tailored mechanical properties.