We report the facile synthesis of carbon dots with tunable fluorescence from unzipping of photonic crystals and their application in LEDs, which may provide an insight into the creation of multifunctional carbon dots adapted for various applications such as in optoelectronics, sensing, or bioimaging.

We report a novel approach for quickly fabricating poly(NVP-co-NMA) hydrogels (NVP = 1-vinyl-2-pyrrolidone, NMA = N-methylolacrylamide) by using plasma-ignited frontal polymerization (PIFP). Frontal polymerization was initiated by igniting the upper side of the mixture with plasma. Once initiated, no additional energy was required for the polymerization to occur. We thoroughly investigated the influence of the molar ratios of NVP/NMA on the properties of poly(NVP-co-NMA) hydrogels via this PIFP approach. The swelling rate, swelling behavior, and morphology of polymer hydrogels prepared via PIFP were comparatively investigated on the basis of water contact angle, swelling measurement and scanning electron microscopy (SEM). Results show that the swelling property of poly(NVP-co-NMA) hydrogels depends on NVP/NMA molar ratios, and the swelling capacity of the hydrogels prepared using PIFP approach is superior to that obtained using traditional batch polymerization (BP) method. More interestingly, these hydrogels, able to absorb quantum dots (QDs), exhibit obvious switching effect via altering the process of swelling and deswelling, which can be developed as QD-based moisture sensor.

We report a facile and rapid approach for the fabrication of CdTe-embedded hydrogels and the selective sensing of these hydrogels toward different analytes. We first synthesized N-acetyl-L-cysteine (NAC)-capped CdTe nanocrystals (NCs) via a microwave-assistance method. Then, taking advantage of frontal polymerization (FP) for fast and easy handling, we facilely prepared CdTe/poly(Nmethylolacrylamide) (CdTe/PNMA) and CdTe/poly(N-methylolacrylamide-co-dimethyl diallyl ammonium chloride) (CdTe/poly(NMA-co-DMDAAC)) fluorescent hydrogels. A variety of features for the preparation of CdTe-embedded hydrogels, such as the initiator, solvent concentrations and the ratio of different monomers were thoroughly investigated. The spectroscopic studies reveal that the CdTe-embedded hydrogels prepared via FP exhibit high quantum yield and excellent photoluminescence (PL) stability. By measuring the change in PL properties of the samples, we found that the CdTe/PNMA hydrogels are responsive to different kinds of heavy metal ions, and the CdTe/ poly(NMA-co-DMDAAC) fluorescent slices exhibit fluorescent sensing toward organoamines.

Implantation of a scaffold into the body in a safe and convenient manner remains a challenge in the repair of patient bone defect. In the present study, a strategy for fabrication of the redox-sensitive nanofibers with a core−shell structure that can deliver the growth factors in a tunable manner is presented. Poly(ethylene oxide) (PEO) and bone morphogenetic protein 2 (BMP-2) forms the inner core region, and a mixture of poly(epsilon-caprolactone) (PCL) and redox-responsive c-6A PEG−PCL nanogel with −S−S− bond forms the outer shell. The redox-sensitive shell of the nanofibers can respond the change of the GSH (glutathione) concentration and thus regulate the BMP-2 release behavior in vitro and in vivo. In vitro cytotoxicity results indicated that the redox-sensitive nanofiber had good osteoinduction. The in vivo results demonstrated that the nanofibers exhibited a capacity of prompting new bone generation in the bone defect. Therefore, the redox-responsive nanofiber in the present study may be of great potential for application in bone reconstruction.

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Abstract:To address the problem regarding poor shear resistance of commonly employed polymers for oil displacement, modified nano-SiO 2 /AA/AM copolymer (HPMNS) oil displacement agents were synthesized using acrylic acid (AA), acrylamide (AM), and modified nano-SiO 2 of different modification degrees as raw materials. HPMNS was characterized by means of infrared spectroscopy (IR), nuclear magnetic resonance ( 1 H-NMR, 13 C-NMR), dynamic/static light scattering, and scanning electron microscope. A comparative study of the shear resistance properties for partially hydrolyzed polyacrylamide (HPAM) and HPMNS was conducted. Compared to HPAM, the introduced hyperbranched structure endowed HPMNS with good shear resistance, which was quantified from the viscosity retention ratio of the polymer solutions. From the perspective of rheological property, HPMNS also showed great shear stability after shearing by a Mixing Speed Governor and porous media shear model. Furthermore, with a higher degree of modification, HPMNS-2 had better shear stability in terms of viscosity and rheological property than HPMNS-1. The phenomena were due to its lower hydrodynamic radius, weight-average molecular weight, and better flexibility of its molecular chains. In addition, upon the indoor displacement test, the resistance factor and residual resistance factor values of HPMNS-2 were higher than those of HPAM. This behavior is beneficial for increasing oil recovery.

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Carbon dots prepared with the adoption of ubiquitous natural fruit juices as precursors have good applications in pH sensing, patterning and bioimaging.