Given the increasing environmental and energy issues, materials with the ability to repair themselves following damage are highly desirable because this self-healing property can prolong the lifespan of materials and reduce replacement costs. Host–guest assemblies are a powerful approach to create supramolecular materials with versatile functions. Here, a new mode of radical polymerization is demonstrated which is achieved via magnetocaloric effect to fabricate novel host–guest supramolecular gels within 5 min. The resulting gels can repair themselves spontaneously when damaged, without the assistance of any external stimuli, and possess great mechanical strength. Moreover, the Fe₃O₄-doped supramolecular gels show accelerated self-healing (from 24 h to 3 h) under an applied magnetic field, which is attributed to the synergy between host–guest healing and a magnetocaloric effect. This strategy might open a promising avenue for accelerating the use of host–guest assemblies to rapidly build robust materials.

We report the facile synthesis of poly(VI-co-MAA) superabsorbent polyampholytic hydrogels (VI = N-vinylimidazole, MAA = methacrylic acid) via plasma-ignited frontal polymerization (PIFP). On igniting the top surface of the reactants with air plasma, frontal polymerization occurred and poly(VI-co-MAA) hydrogels were obtained within minutes. The preparation parameters were investigated, along with swelling capacity, morphology, and chemical structures of poly(VI-co-MAA) hydrogels. Interestingly, the hydrogels are superabsorbent in water and show ampholytic characteristic toward pH. Moreover, the hydrogels are able to capture cationic dyes through electrostatic interaction, offering the potential for further development as dye adsorbents for water purification. In addition, nanocomposite hydrogels were obtained by embedding quantum dots (carbon dots or CdS nanocrystals) into the polymer matrix, which endows the nanocomposite hydrogels with favorable fluorescence and potential applications in bioimaging and biosensing. The results indicate that FP can be applied as an alternative means for facile synthesis of multifunctional hydrogels with additional efficiency and energy-saving. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 912–920

The exploration of methods allowing chemical reactions to be carried out at ultrasmall scales is of great scientific and technological interest. We report herein a microfluidic spinning technique for the fabrication of softened-polymer microarrays for use as multidimensional microreactors and the application of these microreactors in the synthesis of fluorescent nanocrystals. Highly aligned microarrays and controlled-angle grids were readily constructed from microfluidically spun polyvinylpyrrolidone (PVP) microfibers. One–zero dimensional (1D–0D), one–one dimensional (1D–1D), and one–two dimensional (1D–2D) microreactors were then produced by the intersections between microfibers and droplets, crossed microfibers, and microfibers and a PVP film, respectively; each component can be doped with different reagents. Specific examples show that these multidimensional microreactors enable the in situ generation of fluorescent nanocrystals without ligands within minutes.

The exploration of methods allowing chemical reactions to be carried out at ultrasmall scales is of great scientific and technological interest. We report herein a microfluidic spinning technique for the fabrication of softened-polymer microarrays for use as multidimensional microreactors and the application of these microreactors in the synthesis of fluorescent nanocrystals. Highly aligned microarrays and controlled-angle grids were readily constructed from microfluidically spun polyvinylpyrrolidone (PVP) microfibers. One–zero dimensional (1D–0D), one–one dimensional (1D–1D), and one–two dimensional (1D–2D) microreactors were then produced by the intersections between microfibers and droplets, crossed microfibers, and microfibers and a PVP film, respectively; each component can be doped with different reagents. Specific examples show that these multidimensional microreactors enable the in situ generation of fluorescent nanocrystals without ligands within minutes.

We describe a facile fabrication of white light-emitting cadmium sulfide (CdS)-poly(HEA-co-NVK) nanocomposites [2-hydroxyethyl acrylate (HEA) and N-vinylcarbazole (NVK)] via plasma-ignited frontal polymerization (PIFP), a novel and rapid reaction mode of converting monomers into polymers in minutes. Frontal polymerization was initiated by igniting the upper side of the reactant with plasma. Once initiated, no additional energy was required for the polymerization to occur. The chemical functional groups of the as-prepared nanocomposites were thoroughly investigated using Fourier transform infrared spectra. The dependence of the front velocity and front temperature on the initiator concentration and weight ratios of HEA/NVK was also investigated in detail. Perhaps more interestingly, the white light-emitting materials synthesized by ingeniously incorporating the compensating colors of yellow emitting from 3-(trimethoxysilyl)-1-propanethiol-capped CdS nanocrystals and blue emitting from carbazole-containing polymer were conveniently applied onto a commercial UV light-emitting diode (LED) to generate white LEDs. The subtle change in the weight ratios of CdS/NVK can significantly impact the color hue. The white light becomes gradually colder with the increase of NVK, but becomes gradually warmer with the increase concentration of CdS nanocrystals. In a broad perspective, these white light-emitting materials designed by PIFP approach will open a new pathway to develop “QD-polymer nanocomposite down-conversion LED” in a fast and efficient way. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

In this work, a dually sensitive colloidal crystal (CC)-loaded hydrogel has been synthesized via frontal polymerization (FP) in a facile and rapid way. First, a polystyrene CC film was fabricated by vertical deposition on the inner wall of a test tube. Then, a mixture of acrylic acid (AAc), 2-hydroxyethyl methacrylate (HEMA), and glycerol along with the initiator and crosslinker was added to this test tube to carry out FP, resulting in the formation of CC-loaded hydrogel. The influence of the mass ratios of HEMA/AAc on front velocity and temperatures were studied. The swelling behavior, the morphology, and the stimuli-responsive behavior of the CC-loaded hydrogels prepared via FP were thoroughly investigated on the basis of swelling measurement, scanning electron microscopy, and reflection spectra. Results show that the as-prepared CC-loaded hydrogels exhibit excellent dual sensitivity to both methanol concentrations and pH values with very short response time, which can be observed visually without the aid of instruments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Atmospheric air plasma was created and applied in the frontal polymerization (FP) of fabricating poly(HPA-co-VeoVa 10) amphiphilic gels (HPA = 2-hydroxypropyl acrylate, VeoVa 10 = vinyl versatate) with enhanced physicochemical properties. In plasma-ignited frontal polymerization (PIFP), once ignited by air plasma, no further energy or treatment was required for the following polymerization. In this system, the comparison between PIFP and thermal frontal polymerization (TFP) was conducted and observed that PIFP and TFP differ considerably in terms of swelling capacity, morphology and component distribution of the products. This finding is of great importance that the simultaneous generation of active radicals in the initial stage can spread throughout reactant and anchor on the synthetic polymer with the assistance of FP. More interestingly, the PIFP-synthesized copolymer possesses remarkable selective absorption towards organic solvents, which can be facilely manipulated by varying the weight ratios of HPA/VeoVa 10. Obviously, these polymer products could serve as an “organic solvent scavenger” in the field of industrial wastewater treatment. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

We reported a new facile method to synthesize superhydrophobic nanosilica using glycidoxypropyltrimethoxysilane and dodecylamine as treatment agents. Also, we systemically investigate their performance in reinforcement of poly(dimethylsiloxane) (PDMS) rubber. Fourier transform infrared spectrum, contact angle (CA) and thermogravimetric analysis (TGA) measurements were used to characterize the modified nanosilica. Results show that the inherent hydrophilicity of parent nanosilica surface can be greatly altered through this modification method. The CA of as-prepared superhydrophobic nanosilica can reach 160.2°. The properties of as-prepared modified nanosilica-filled PDMS composites were systemically investigated by dynamic rheological test, scanning electron microscopy, TGA, dynamic mechanical analysis. These as-prepared superhydrophobic nanosilica exhibit uniform dispersion in the PDMS matrix, and their composites also show good mechanical properties and distinct advantage on thermal stability compared with those of the pure silica-filled PDMS composites. Also described is the probable mechanism for the reinforcement of as-prepared superhydrophobic nanosilica-filled PDMS. POLYM. COMPOS., 31:1628–1636, 2010. © 2009 Society of Plastics Engineers

We report a new facile strategy for quickly synthesizing poly(2-hydroxyethyl acrylate-co-vinyl versatate) amphiphilic gels with excellent physicochemical properties by frontal free-radical polymerization. The appropriate amounts of 2-hydroxyethyl acrylate, vinyl versatate (VeoVa 9) and ammonium persulfate initiator were mixed together at ambient temperature in the presence of N-methyl-2-pyrrolidone as the solvent medium. Frontal polymerization (FP) was initiated by heating the wall of the tube with a soldering iron. Once initiated, no further energy was required for the polymerization to occur. The dependence of the front velocity and front temperature on the initiator concentration was investigated. The front temperatures were between 132 and 157 °C, depending on the initiator concentration. The morphology, swelling rate, and swelling behavior of amphiphilic gels prepared via FP were comparatively investigated on the basis of scanning electron microscopy, water contact angle, and swelling measurements. Results show that the amphiphilic gels prepared via FP behave with good swelling capacity both in water and organic solvents. The FP can be exploited as an alternative means for synthesis of amphiphilic gels with additional advantages of fast and efficient way. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 823–831, 2010

We report a new facile strategy for quickly synthesizing pH sensitive poly(VI-co-HEA) hydrogels (VI = N-vinylimidazole; HEA = 2-hydroxyethyl acrylate) by frontal polymerization. The appropriate amounts of VI, HEA, and ammonium persulfate (APS)/N,N,N′,N′-tetramethylethylenediamine (TMEDA) couple redox initiator were mixed together at ambient temperature in the presence of glycerol as the solvent medium. Frontal polymerization (FP) was initiated by heating the upper side of the mixture with a soldering iron. Once initiated, no further energy was required for the polymerization to occur. The dependence of the front velocity and front temperature on the VI/HEA weight ratios were investigated. The pH sensitive behavior, morphology, and heavy metal removal study of poly(VI-co-HEA) hydrogels prepared via FP were comparatively investigated on the basis of swelling measurements, scanning electron microscopy, and inductively coupling plasma spectrometer. Results show that the poly(VI-co-HEA) hydrogels prepared via FP exhibit good pH sensitivity and adsorption capacity. The FP can be exploited as an alternative means for synthesis of pH sensitive hydrogels in a fast and efficient way. The as-prepared hydrogels can be applied to remove heavy metals. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4005–4012, 2010

We report an available approach for quickly fabricating CdS QD-polymer nanocomposites via frontal polymerization (FP). First, we synthesized (3-mercaptopropyl)-1-trimethoxysilane (MPS)-capped CdS quantum dots (QDs). With these MPS-capped CdS QDs containing mercapto groups, MPS-capped CdS QDs can be easily incorporated into a poly(N-methylolacrylamide) (PNMA) matrix via FP. A variety of features for preparing QD-polymer nanocomposites, such as initiator concentration and CdS concentration, were thoroughly investigated. The fluorescence properties of QD-polymer nanocomposites prepared via FP are comparatively investigated on the basis of ultraviolet–visible (UV–vis) spectra and photoluminescence (PL) spectra. Results show that the PL intensity of QD-polymer nanocomposites prepared via the FP method is superior to that obtained by the traditional batch polymerization (BP) method. In addition, by measuring the changes of PL intensity of the samples immersed in different concentrations of copper acetate solution, we found the QD-polymer nanocomposites can be ultrasensitive to copper ions. This FP process can be exploited as a facile and rapid way for synthesis QD-polymer nanocomposites on a large scale, avoiding the fluorescence quenching of nanocrystals during incorporation nanocrystals into polymer matrices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2170–2177, 2010

BACKGROUND: The reaction temperature for frontal polymerization (FP) initiated by redox initiators can be greatly decreased compared with FP initiated by peroxide initiator and disulfide initiator. We report the synthesis of poly(hydroxyethyl acrylate)s via free radical FP using benzoyl peroxide (BPO)/N,N-dimethylaniline (DMA) and ammonium persulfate (APS)/N,N,N′,N′-tetramethylethylenediamine (TMEDA) couples as redox initiators at ambient pressure.

RESULTS: The results show that unlike the phenomenon of bubbles and ‘fingers’ when using BPO alone, a self-sustaining and stable front can be obtained when the [DMA]/[BPO] ratio is higher than 1 (mol/mol). A slight increase of the DMA (or TMEDA) reductant concentration causes a marked decrease of front temperature to 53 °C (or 61 °C).

CONCLUSION: We investigated the effects of the ratio of the oxidant to the reductant and the initiator and monomer concentrations on certain parameters of FP: formation of bubbles, front velocity and front temperature. This opens the way to the potential development of FP using more appropriate monomers with low boiling points. Copyright © 2009 Society of Chemical Industry

We report on a new strategy for fabricating well-defined POSS-based polymeric materials with and without solvent by frontal polymerization (FP) at ambient pressure. First, we functionalize polyhedral oligomeric silsesquioxane (POSS) with isophorone diisocyanate (IPDI). With these functionalized POSS-containing isocyanate groups, POSS can be easily incorporated into a poly(N-methylolacrylamide) (PNMA) matrix via FP in situ. Constant velocity FP is observed without significant bulk polymerization. The morphology and thermal properties of POSS-based hybrid polymers prepared via FP are comparatively investigated on the basis of scanning electronic microscopy (SEM) and thermogravimetric analysis (TGA). Results show that the as-prepared POSS-based polymeric materials exhibit a higher glass transition temperature than that of pure PNMA, ascribing to modified POSS well-dispersed in these hybrid polymers. Also, the products with different microstructures display different thermal properties. The pure PNMA exhibits a featureless morphology, whereas a hierarchical morphology is obtained for the POSS-based polymeric materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1136–1147, 2009

The first synthesis of poly(N-vinylpyrrolidone) without solvent by free-radical frontal polymerization at ambient pressure is reported. The appropriate amounts of two reactants N-vinyl-2-pyrrolidone (NVP) and initiator 2,2′-azobis-isobutyronitrile (AIBN) without solvent were mixed together at ambient temperature. Frontal polymerization was initiated by heating the wall of the tube with a soldering iron, and the resultant hot fronts were allowed to self-propagate throughout the reaction vessel. Once initiated, no further energy was required for polymerization to occur. To suppress the fingers of molten monomer, a small amount of nanosilica was added. The dependence of the front velocity and front temperature on the AIBN concentration was thoroughly investigated. The as-prepared polymers were characterized by gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). Results show that without postpolymerization solvent removal, waste production can be reduced. Solvent-free FP could be exploited as a means for preparation of PVP with the potential advantage of higher throughput than solvent-based methods. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2177–2185, 2008