A reversibly cross‐linked epoxy resin with efficient reprocessing and intrinsic self‐healing was prepared from a diamine Diels‐Alder (DA) adduct cross‐linker and a commercial epoxy oligomer. The newly synthesized diamine cross‐linker, comprising a DA adduct of furan and maleimide moieties, can cure epoxy monomer/oligomer with thermal reversibility. The reversible transition between cross‐linked state and linear architecture endows the cured epoxy with rapid recyclability and repeated healability. The reversibly cross‐linked epoxy fundamentally behaves as typical thermosets at ambient conditions yet can be fast reprocessed at elevated temperature like thermoplastics. As a potential reversible adhesive, the epoxy polymer with adhesive strength values about 3 MPa showed full recovery after repeated fracture‐thermal healing processes. The methodology explored in this contribution provides new insights in modification of conventional engineering plastics as functional materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2094–2103

A novel physically linked double-network (DN) hydrogel was prepared by natural polymer KGM and synthetic polymer PAAm. The DN hydrogels exhibit good mechanical properties, cell adhesion properties, and can be freely shaped, making such hydrogels promising for tissue engineering scaffolds.

Citation: Gao Y, Dong X, Wang L et al (2015) Flow-induced crystallization of long chain aliphatic polyamides under a complex flow field: Inverted anisotropic structure and formation mechanism. Polymer. 73: 91-101. The present work deals with the flow-induced multiple orientations and 13 crystallization structure of polymer melts under a complex flow field. This complex 14 flow field is characteristic of the consistent coupling of extensional "pulse" and 15 closely followed shear flow in a narrow channel. Utilizing an ingenious combination 16 of an advanced micro-injection device and long chain aliphatic polyamides (LCPA), 17 the flow-induced crystallization morphology was well preserved for ex-situ 18 2 synchrotron micro-focused wide angle X-ray scattering (μWAXS) as well as small 19 angle X-ray scattering (SAXS). An inverted anisotropic crystallization structure was 20 observed in two directions: perpendicular and parallel to the flow direction (FD). The 21 novel anisotropic morphology implies the occurrence of wall slip and "global" 22 fountain flow under the complex flow field. The mechanism of structure formation is 23 elucidated in detail. The experimental results clearly indicate that the effect of 24 extensional pulse on the polymer melt is restrained and further diminished due to 25 either the transverse tumble of fountain flow or the rapid retraction of stretched high 26 molecular weight tails. However, the residual shish-kebab structures in the core layer 27 of the far-end of channel suggest that the effect of extensional pulse should be 28 considered in the small-scaled geometries or under the high strain rate condition. 29

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The present work investigated the influence of organoclay (organo-montmorillonite, OMMT) on the phase separation behavior and morphology evolution of solution polymerized styrene-butadiene rubber (SSBR)/low vinyl content polyisoprene (LPI) blends with rheological methodology. It was found that the incorporation of OMMT not only reduced the droplet size of the dispersion phase, slowed down the phase separation kinetics, also enlarged the processing miscibility window of the blends. The determination on the wetting parameters indicated that due to the oscillatory shear effect, the OMMT sheets might localize at the interface between the two phases and act as compatibilizer or rigid barrier to prevent domain coarsening, resulting in slow phase separation kinetics, small droplet size, and stable morphology. The analysis of rheological data by the Palierne model provided further confirmation that the addition of OMMT can decrease the interfacial tension and restrict the relaxation of melt droplets. Therefore, a vivid "sea-fish-net" model was proposed to describe the effect of OMMT on the phase separation behavior of SSBR/LPI blends, in which the OMMT sheets acted as the barrier (net) to slow down the domain coarsening/coalescence in phase separation process of SSBR/LPI blends.

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