In this work, poly((PMMA-b-VI)-co-AA) (MMA = methyl methacrylate; VI = 1-vinylimidazole; AA = acrylic acid) hydrogels and poly((PMMA-b-VI)-co-AA)/TPU (TPU = thermoplastic polyurethane) IPN (interpenetrating polymer networks) hydrogels have been fabricated via versatile infrared laser ignited frontal polymerization by using poly(PMMA-b-VI) macromonomer as the mononer. The frontal velocity and T_max (the highest temperature that the laser beam detected at a fixed point) can be adjusted by varying monomer weight ratios, the concentration of BPO (BPO = benzoyl peroxide) and the amount of TPU. Moreover, the addition of TPU enhances the reactant viscosity to suppress the “fingering” of frontal polymerization (FP) and decrease T_max of the reaction, providing a new inert carrier (TPU) to assist FP. Through the characterization of Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and differential scanning calorimetry (DSC), the desired structure can be proved to exist in the IPN hydrogels. Furthermore, poly((PMMA-b-VI)-co-AA)/TPU IPN hydrogels possesses more excellent mechanical behaviors than hydrogels without IPN structure. Besides, the poly((PMMA-b-VI)-co-AA) hydrogels present splendid sensitive properties toward substances of different flavor including sourness (CA, citric acid or GA, gluconic acid), umami (SG, sodium glutamate), saltiness (SC, sodium chloride), sweetness (GLU, glucose), enabling their potential as artificial tongue-like sensing materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1210–1221

Autonomous mechanical mass transportation for cargos on the microscale with no need of continuous external powering is of great scientific and technological interest due to their extensive applications. However, it is still challenging to create a self-driven system applicable to diverse micromaterial transportation demands. In this work, we developed a novel autonomous conveyer gel driven by frontal polymerization (FP). The chemical wave produced in FP was stable, and self-propagating with a constant velocity, which can be easily monitored by thermal imaging or fluorescence labeling. We investigated the influence of the initiation temperature, swelling ratio of the gel substrate, and the size of the cargos on the motion of driven behavior. Results showed that the driving velocity can be well controlled by altering the initiation temperatures of FP. The swelling ratio and the size of the cargos had a key impact on the feasibility of self-driven behavior. In addition, powerful driven capability by FP was demonstrated by successfully transporting cargos in series, and further applied for targeted synthesis of CdS nanocrystals. The methodology developed here provides an effective way to convert chemical energy to mechanical work, and may be useful in energy conversion and utilization, mass transportation and other applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1323-1331

Anisotropic fluorescent hybrid microfibers with distinct optical properties and delicate architectures have aroused special interest because of their potential applications in tissue engineering, drug delivery, sensors, and functional textiles. Microfluidic systems have provided an ideal microreactor platform to produce anisotropic fibers due to their simplified manipulation, high efficiency, flexible controllability, and environmental-friendly chemical process. Here a novel microfiber reactor based on a microfluidic spinning technique for in situ fabrication of nanocrystals loaded anisotropic fluorescent hybrid microfibers is demonstrated. Multiple nanocrystal reactions are carried out in coaxial flow-based microdevices with different geometric features, and various nanocrystals loaded microfibers with solid, string-of-beads and Janus topographies are obtained. Moreover, the resulted anisotropic fluorescent hybrid microfibers present multiple optical signals. This strategy contributes a facile and environmental-friendly route to anisotropic fluorescent hybrid microfibers and might open a promising avenue to multiplex optical sensing materials.

In this work, we report a versatile infrared laser ignited frontal polymerization technique for the fabrication of a series of poly(DMC-co-HPA) hydrogels (DMC = methacryloxyethyltrimethyl ammonium chloride, HPA = hydroxypropyl acrylate). Because the method is based on the exothermic reaction, no further energy is required in the reaction once it is initiated. Moreover, we have found the polymerization process is a pure frontal polymerization model without involving any other reaction process. The dependence of frontal velocity and temperature on the reaction time is thoroughly discussed. The as-prepared hydrogels are pH-responsive and their maximum equilibrium swelling ratio could reach ∼3,890%. Also, the as-prepared poly(DMC-co-HPA) hydrogels capable of adsorption/desorption switching performance can be utilized for heavy metal ion removal in wastewater treatments. Interestingly, the hydrogels can float on the water surface after intaking heavy metal ions by the combination of kerosene and polyoxyethylene sorbitan monolaurate (Tween 20) in hydrogel components, greatly enhancing treatment efficiency. We believe the method described herein to rapidly construct functional hydrogels with the ability to remove heavy metal ions may find unique applications in emergency processing of water pollution. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2085–2093

Mechanochromic materials which control their color variation by straightforward effective mechanical stimuli are useful for applications including switches, display devices, and sensors. It is still challenging to create mechnochromic materials with wide-range color tunability, fast response, and sensitivity to pressure <10 kPa. Here a facile strategy to fabricate very sensitive and reversibly mechanochromic elastic photonic hydrogels (EPHs) is demonstrated. The hydrogels exhibit reversible full-color variation within 1 s under each compression–decompression cycle. Importantly, EPH films display versatile touch-induced chromatic behavior even under forces below 0.5 N or pressures down to 1 kPa. Furthermore, rewritable displays on EPH films are realized by the exertion of forces without any external inks. This work may provide a new way to develop smart skin materials with integrated functions of tactile sensing and color variation, as well as touch-based flexible displays.

We report a facile strategy for fabricating fluorescent quantum dot (QD)-loaded microbeads by means of microfluidic technology. First, a functional fluorine-containing microemulsion was synthesized with poly[(2-(N-ethylperfluorobutanesulfonamido)ethyl acrylate)-co-(methyl methacrylate)-co-(butyl acrylate)] (poly(FBMA-co-MMA-co-BA)) as the core and glycidyl methacrylate (GMA) as the shell via differential microemulsion polymerization. Then, CdTe QDs capped with N-acetyl-l-cysteine (NAC) were assembled into the poly(FBMA-co-MMA-co-BA-co-GMA) microemulsion particles through the reaction of the epoxy group on the shell of the microemulsion and the carboxyl group of the NAC ligand capped on the QDs. Finally, fluorescent microbeads were fabricated using the CdTe QD-loaded fluorine-containing microemulsion as the discontinuous phase and methylsilicone oil as the continuous phase by means of a simple microfluidic device. By changing flow rate of methylsilicone oil and hybrid microemulsion system, fluorescent microbeads with adjustable sizes ranging from 290 to 420 µm were achieved. The morphology and fluorescent properties of the microbeads were thoroughly investigated using optical microscopy and fluorescence microscopy. Results showed that the fluorescent microbeads exhibited uniform size distribution and excellent fluorescence performance. © 2014 Society of Chemical Industry