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Smart hydrogels responsive to external stimuli are promising for various applications such as soft robotics and smart devices. High mechanical strength and fast response rate are particularly important for the construction of hydrogel actuators. Herein, tough hydrogels with rapid response rates are synthesized using vinyl‐functionalized poly(N‐isopropylacrylamide) (PNIPAM) microgels as macro‐crosslinkers and N‐isopropylacrylamide as monomers. The compression strength of the obtained PNIPAM hydrogels is up to 7.13 MPa. The response rate of the microgel‐crosslinked hydrogels is significantly enhanced compared with conventional chemically crosslinked PNIPAM hydrogels. The mechanical strength and response rate of hydrogels can be adjusted by varying the proportion of monomers and crosslinkers. The lower critical solution temperature (LCST) of the PNIPAM hydrogels could be tuned by copolymerizing with ionic monomer sodium methacrylate. Thermo‐responsive bilayer hydrogels are fabricated using PINPAM hydrogels with different LCSTs via a layer‐by‐layer method. The thermo‐responsive fast swelling and shrinking properties of the two layers endow the bilayer hydrogel with anisotropic structures and asymmetric response characteristics, allowing the hydrogel to respond rapidly. The bilayer hydrogels are fabricated into clamps to grab small objects and flowers that mimicked the closure of petals, and it shows great application prospects in the field of actuators. [ABSTRACT FROM AUTHOR]

Abstract: Attaining control on charge injection properties is significant for meaningful applications of organic field‐effect transistors (OFETs). Here, molecular electron‐doping is applied with an air‐stable dimer dopant for n‐type OFETs based on (naphthalene diimide–diketopyrrolopyrrole) polymer hosts. Through investigating the doping effect on contact and transport properties, it is found that the electron transport increases in n‐doped OFETs at low doping regime with remaining large on/off ratios. These favorable meliorations are reconciled by the mitigated impacts of contact resistance and interfacial traps, as well as the surface morphology exhibiting features of increased ordering. The occurrence of doping in the presence of dimer dopants is evidenced by the observed shift of Fermi level toward vacuum level coupled with compositional analysis. Without applying vacuum‐deposition‐based contact doping, charge injection efficiencies are gained without losing OFET characteristics using the solution‐based methodology. [ABSTRACT FROM AUTHOR]

Shape-memory polymers are highly desirable in implant biomaterials for minimally invasive surgical procedures. However, most of them lack suitable transition temperature, mechanical properties, and biodegradability. Here, a series of shape-memory polyurethanes are synthesized by postcrosslinking in hard-segment domains using a flexible crosslinker. The materials used are all nontoxic and biodegradable. Through postcrosslinking of unsaturated linear polyurethanes with flexible and biodegradable crosslinker, the crosslinked polyurethanes (CPUs) show good mechanical properties, excellent shape-memory property, and repeatability. The post-crosslinking structure and shape-memory mechanism of CPUs are investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis tests. The crosslinker endows the fixed phase enough crosslinking and inserts in the hard segments to give the fixed phase certain elasticity. The elastic hard segments make them form more hydrogen bonds with soft segments during shape deformation. The low-molecular-weight poly (ε-caprolactone) offers the samples a shape-memory transition temperature at around 37 °C, which is suitable for implant devices in vivo. This work expands CPUs with an elastic crosslinking structure as potential candidates for implant biomaterials. Since the post-crosslinking polymerization is facile, it can be convenient for industrial production. [ABSTRACT FROM AUTHOR]

Low-molecular-weight poly(ethylene glycol) (PEG) is deliberately incorporated into synthesized swellable poly(ethylene oxide) (PEO) membranes via a facile post-treatment strategy. The membranes exhibit both larger fractional free volume (FFV) and a higher content of CO2-philic building units, resulting in significant increments in both CO2 permeability and CO2/H2 selectivity. The separation performance correlates nicely with the microstructure of the membranes. This study may provide useful insights in the formation and mass transport behavior of highly efficient polymeric membranes applicable to clean energy purification and CO2 capture, and possibly bridge the material-induced technology gap between academia and industry. [ABSTRACT FROM AUTHOR]

Invisible aligners have been widely used in orthodontic treatment but still present issues with plaque formation and oral mucosa abrasion, which can lead to complicated oral diseases. To address these issues, hydrophilic poly(sulfobetaine methacrylate) (polySBMA) coatings with lubricating, antifouling, and antiadhesive properties have been developed on the aligner materials (i.e., polyethylene terephthalate glycol, PETG) via a simple and feasible glycidyl methacrylate (GMA)‐assisted coating strategy. Poly(GMA‐co‐SBMA) is grafted onto the aminated PETG surface via the ring‐opening reaction of GMA (i.e., “grafting to” approach to obtain G‐co‐S coating), or a polySBMA layer is formed on the GMA‐grafted PETG surface via free radical polymerization (i.e., “grafting from” approach to obtain G‐g‐S coating). The G‐co‐S and G‐g‐S coatings significantly reduce the friction coefficient of PETG surface. Protein adsorption, bacterial adhesion, and biofilm formation on the G‐co‐S‐ and G‐g‐S‐coated surfaces are significantly inhibited. The performance of the coatings remains stable after storage in air or artificial saliva for 2 weeks. Both coatings demonstrate good biocompatibility in vitro and is not caused irritation to the oral mucosa of rats in vivo over 2 weeks. This study proposes a promising strategy for the development of invisible aligners with improved performance, which is beneficial for oral health treatment. [ABSTRACT FROM AUTHOR]