The Multi-Step Chain Extension for Waterborne Polyurethane Binder of -Aramid Fabrics.

The comprehensive balance of the mechanical, interfacial, and environmental requirements of waterborne polyurethane (WPU) has proved challenging, but crucial in the specific application as the binder for high-performance polymer fiber composites. In this work, a multi-step chain extension (MCE) method was demonstrated using three kinds of small extenders and one kind of macro-chain extender (CE) for different chain extension steps. One dihydroxyl blocked small molecular urea (1,3-dimethylolurea, DMU) was applied as one of the CEs and, through the hybrid macrodiol/diamine systems of polyether, polyester, and polysiloxane, the WPU was developed by the step-by-step optimization on each chain extending reaction via the characterization on the H-bonding association, microphase separation, and mechanical properties.

insight into the self-assembly evolution of ABA-type block copolymers in water during the gelation process using infrared spectroscopy and near-infrared spectroscopy.

As a kind of thermo-responsive hydrogel, amphiphilic block copolymers are widely investigated. However, the molecular mechanism of their structural change during the gelation process is still limited. Here, a well-controlled triblock copolymer poly(,-dimethylacrylamide)--poly(diacetone acrylamide)--poly(,-dimethylacrylamide) (PDMAA--PDAAM--PDMAA) was synthesized.

Topology Reliable LCST-Type Behavior of ABA Triblock Polymer and Influence on Water Condensation and Crystallization.

As a kind of smart material, thermoresponsive hydrogels are widely investigated and applied in many fields. Due to the limitation of the freezing temperature of the water, it is a challenge to further broaden their sol-gel transition temperature (T ) range, especially below 0 °C. Herein, the lower critical solution temperature type of amphiphilic ABA triblock copolymers, synthesized via two-step reversible addition-fragmentation chain transfer (RAFT) polymerization is demonstrated.

Achievement of Both Mechanical Properties and Intrinsic Self-Healing under Body Temperature in Polyurethane Elastomers: A Synthesis Strategy from Waterborne Polymers.

Inspired by the growing demand for smart and environmentally friendly polymer materials, we employed 2,2'-disulfanediyldianiline (22DTDA) as a chain extender to synthesize a waterborne polyurethane (WPUR). Due to the ortho-substituted structure of the aromatic disulfide, the urea moieties formed a unique microphase structure in the WPUR, its mechanical strength was enhanced more 180 times relative to that of the material prepared without 22DTDA, and excellent self-healing abilities at body temperature in air or under ultrasound in water were obtained. If the self-healing process was carried out at 37 °C, 50 °C or under ultrasound, the ultimate tensile strength and elongation at break of the healed film could reach 13.

ABA-type triblock copolymer micellar system with lower critical solution temperature-type sol-gel transition.

A temperature sensitive sol-gel transition induced by the self-assembly of amphiphilic copolymers and its application in industry have been the objects of increasing study. We demonstrate here a two-step, reversible addition-fragmentation chain transfer (RAFT) polymerization of an ABA-type copolymer consisting of poly(N,N-dimethylacrylamide)-b-poly(diacetone acrylamide)-b-poly(N,N-dimethylacrylamide) (PDMAA-b-PDAAM-b-PDMAA). This copolymer can be easily dispersed in water, and this dispersion is critical for its lower critical solution temperature (LCST)-type sol-gel transition, which was monitored using dynamic light scattering (DLS), transmission electron microscopy (TEM), and rheology analysis, in addition to temperature-dependent H nuclear magnetic resonance (H NMR) and Fourier transform infrared spectroscopy (FTIR).

Self-Healing Polycaprolactone Networks through Thermo-Induced Reversible Disulfide Bond Formation.

Polycaprolactone (PCL) networks with disulfide bonds are synthesized through a thiol-ene "click" reaction. The PCL networks have various functional properties, including self-healing, shape memory, reprocessability, and degradability. Pronouncedly, a healing efficiency of 92% on the yield strength of the PCL network is obtained after heating for 1 h at 60 °C.

The microcapsule-type formaldehyde scavenger: the preparation and the application in urea-formaldehyde adhesives.

The limitation and regulation of formaldehyde emissions (FE) now shows great importance in wood-based materials such as plywood and particle board manufactured for building and furnishing materials. The widely used formaldehyde-based adhesives are one of the main sources of FE from the wood products. In this work, a new kind of long-term effective formaldehyde scavenger in the microcapsule form was prepared by using an intra-liquid desiccation method.

Synthesis of polystyrene/polysilsesquioxane core/shell composite particles via emulsion polymerization in the existence of poly(γ-methacryloxypropyl trimethoxysilane) sol.

Here, we synthesized the polystyrene/polysilsesquioxane (PS/PSQ) core/shell latex particles via emulsion polymerization, which behave as an amusing morphology. First, the nanosized PSQ particles were prepared by the hydrolysis-condensation reaction of γ-methacryloxypropyl trimethoxysilane (MPTS) in ethanol medium. Subsequently, the as-obtained methacryloxypropylene functionalized PSQ (PMPTS) sol was directly added into the emulsion system of styrene (St) monomer, and PS/PSQ composite particles with core/shell structure were obtained through emulsion polymerization.