CHEMICAL ENGINEERING JOURNAL
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2023
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IF 15.1
Min Li,Ying Wang,Xin Zhou,Qi Zhang,Mingyang Chen,Dandan Han,Junbo Gong,Hongzhen Li
In this work, the micro/nano spherulitic hierarchical 2,2′,4,4′,6,6′-hexanitrostilbene (HNS) with the excellent specific surface area was prepared for the first time, which was expected to overcome the agglomeration problems of nanoscale HNS. In detail, poly( N -isopropyl acrylamide) (PNIPAM), polysuccinimide (PSI), and polyvinylpyrrolidone (PVP) were selected as additives to induce forming spherulitic HNS. Leaflike crystals were obtained in the presence of PNIPAM, while spherulitic HNS could be fabricated in the presence of PSI or PVP. And the prepared spherulitic HNS owned nearly 6 times the specific surface area of the raw HNS, with decreased impact sensitivity and advanced melting and decomposition temperatures, demonstrating a good desensitization effect, and a favorable energy release of the hierarchical structure. Moreover, morphological changes under the effect of the molecular weight and concentration of PVP were explored. The approximated morphological evolution of spherulitic HNS was consistent with the classical spherulitic growth by noncrystallographic branching. Furthermore, it was verified that preferential adsorption of PVP and PSI on the HNS inhibits the growth steps of the (200) face and introduces stress to generate crystal defects, which triggers noncrystallographic branching and further spherulitic growth. Overall, the strategy of fabricating micro/nano spherulitic hierarchical energetic materials via polymer-additive induced noncrystallographic branching is promising to solve the problems of nanoscale energetic materials in agglomeration and microscale bulk crystals in low activity.
研究领域:
材料科学
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高能材料
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聚合物科学
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纳米技术
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry B
·
2018
·Vol. 6
·期 48
·8170-8179
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IF 4.776
Yu Cheng,Chao Huang,Dian Yang,Kai Ren,Jie Wei
Bilayer-type hydrogel composites that respond to multiple stimuli provide a useful approach for manufacturing soft actuators and intelligent sensors. In this study, we propose two types of bilayer hydrogel composites (referred to as “N” type and “D” type). The “N” type and the “D” type separately consist of poly(N-isopropylacrylamide) (PNIPAM) and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) bilayer hydrogels, with acrylamide (AM) as the co-monomer. The “N” type hydrogel composite exhibits oriented bending as temperature increases or as environmental salt concentration increases. The “D” type also presents oriented bending as temperature increases. Additionally, it demonstrates bending and changes color based on the pH of the surrounding solution, since it is doped with an acid-based pH-indicator. In a demonstration, we present several straight rods composed of a mixture of “N” and “D” type hydrogel composites that are able to morph into the letters “SOS” under environmental changes (temperature or pH). This can be used as a visual environmental indicator, or as an alarm. Furthermore, we show structures composed of a mixture of “N” and “D” composites imitating the flexible motions of a ballet dancer or a Tai Chi master. These mixed bilayer polymer composites may be used for applications in soft robotics, biomimetic devices, and environmental sensors.
研究领域:
材料科学
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软体机器人
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环境传感
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生物医学工程
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产品关联
DOI
PubMed
高影响因子
Polymer Chemistry
·
2014
·Vol. 5
·期 21
·6244-6255
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IF 5.368
Yuanyuan Xu,Youcheng Li,Xueteng Cao,Qijing Chen,Zesheng An
Reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization in cononsolvents of poly(N-isopropylacrylamide) (PNIPAM) was developed as a versatile strategy for the synthesis of thermoresponsive nanogels with controlled composition, functionality and architecture. Cononsolvents composed of mixtures of methanol, ethanol and isopropanol with water were first screened for their suitability as the media for dispersion polymerization of NIPAM, and water–ethanol (75 : 25, v : v) solution was selected due to good RAFT control, efficient formation of nanogels and low toxicity. RAFT dispersion polymerization of NIPAM in the cononsolvent using poly(N,N-dimethylacrylamide) (PDMA) as the macromolecular chain transfer agent (Macro-CTA) showed good control over the molecular weight, polydispersity and pseudo linear polymerization kinetics, as characterized by gel permeation chromatography (GPC) and 1H NMR. The effect of the molecular weight of Macro-CTA, the degree of polymerization of PNIPAM, the molar ratio of [crosslinker] : [Macro-CTA] and the solid content on the formation and size of nanogels was investigated. The thermal profiles of nanogels were characterized by dynamic light scattering (DLS) both in cononsolvents and water. This cononsolvency strategy for dispersion polymerization was shown to be compatible with the incorporation of hydrophilic comonomers of N-(2-hydroxyethyl)acrylamide (HEAM) and diacetone acrylamide (DAAM). The nanogel containing DAAM was demonstrated for postpolymerization modification using ketone–alkoxyamine chemistry. More importantly, dispersion polymerization in cononsolvents allowed various hydrophobic components, e.g. butyl acrylate (BA), fluorescein O-acrylate (FLA), and 1,6-hexanediol diacrylate (HDDA), to be reliably copolymerized with NIPAM, showing well controlled polymerization, composition, nanogel size and colloidal stability. Finally, an amphiphilic block copolymer PDMA-b-PBA was used as a Macro-CTA to produce the PDMA-b-PBA-b-PNIPAM triblock copolymer and triple-layered nanogel, taking advantage of the solubility of PDMA-b-PBA and the insolubility of PNIPAM in the water–ethanol solution at the polymerization temperature.
研究领域:
高分子化学
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材料科学
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）