Journal of Materials Chemistry B
·
2015
·Vol. 3
·期 28
·5824-5832
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IF 4.726
Yang Wang,Jin Zheng,Yefei Tian,Wuli Yang
To improve the biocompatibility and biodegradability of nanocarriers, well-defined poly(vinylcaprolactam)-based acid degradable nanogels were fabricated for drug delivery via precipitation polymerization in water, where synthetic ketal-based 2,2-dimethacroyloxy-1-ethoxypropane (DMAEP) acted as a cross-linker, and N-(2-hydroxypropyl)methacrylamide (HPMA) served as a co-monomer. Expectedly, we observed that the temperature and pH of the environment play important roles in the performance of the nanogels. The nanogels were reduced in size upon increasing the temperature and showed higher volume phase transition temperature (VPTT) with higher concentration of HPMA. With the incorporation of ketal linkages, the nanogels showed accelerated degradation profiles by lowering the pH and increasing temperature of the incubation medium. When used as nanocarriers of anticancer drug doxorubicin (DOX), compared to non-degradable nanogels with similar components, the acid-degradable nanogels displayed more effective drug controlled release behaviour, low drug leakage of DOX at neutral pH while rapid and sufficient release from the nanogels under acidic conditions. The results of the cytotoxicity and hemolysis assays further highlighted that the acid-degradable nanogel produced no hemolysin but showed excellent viability to normal cells, and the DOX-loaded nanogel exhibited higher proliferation inhibition against tumor cells.
研究领域:
材料科学
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药学
·
生物医学工程
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产品关联
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Qihui Huang,Hui Zheng,Xia Wang,Qi Fu,Tao Gong,Chang Liu,Huijuan Ma,Linmin Ye,Xinping Duan,Youzhu Yuan
Hexamethylene diamine, an important chemical intermediate for polyamides, can be synthesized through the two-step route of caprolactam (CPL) ammonolysis to 6-aminocapronitrile (ACN), followed by hydrogenation. This method has received increasing attention from academia and industry. However, studies on the catalyst structure–performance correlation in CPL ammonolysis are still sporadic. In this work, a series of anatase TiO2 with different oxygen vacancy concentrations was prepared by chemical reduction using NaBH4. The oxygen vacancy on TiO2 surface, presented as Ti3+ sites, substantially enhances the adsorption and activation of NH3, which are demonstrated as the key steps in ammonolysis. Owing to the synergistic effect of Ti3+ and Ti4+ species, the CPL conversion rate and ACN selectivity of 85 and 97%, respectively, are achieved within 250 h. Density functional theory calculations showed that the intermediates on oxygen vacancy-rich TiO2 had a more favorable adsorption energy compared to those on intact TiO2, which is in good agreement with the experimental results.
研究领域:
材料科学
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催化化学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Yuze Zhou,Jiaying Lei,Jing Peng,Tengling Ye,Yumeng Wang,Ruipeng Huang,Yubo Zhang,Yonghui Ren,Yuhong Zhou,Dongyan Tang
Stimuli-responsive poly( N -vinylcaprolactam) (PVCL)-based microgels, which could response to small external environmental changes, have attracted great interests in the fields of biomedicine and nanotechnology. However, the preparation of such microgels meets severe challenge due to their low incorporation efficiency and thermoresponsivity passivation. To address these issues, we select 3-( tert- butoxycarbonyl)- N- vinylcaprolactam (TBVCL), a carboxyl-functionalized VCL derivative, as a comonomer to develop pH/temperature dual-responsive microgels. TBVCL, with a structure similar to VCL, enhances incorporation efficiency and colloidal stability, while reducing thermoresponsivity passivation. The volume phase transition temperature (VPTT) of the microgels can be adjusted over a broad range (19.0–49.5 °C). Notably, the radial swelling ratios of the microgels can be modulated by pH, achieving a maximum swelling ratio of 3. The distinct changes in dissolution-precipitation behavior under different temperatures or pH conditions make these microgels suitable for applications such as smart windows and sensors. Furthermore, this novel approach for fabricating microgels with pH-tunable phase-transition temperatures demonstrates significant potential for the controlled release of nanoparticles (e.g., drugs, catalysts, and quantum dots) and the development of smart nanocrystal-polymer composite sensors.
研究领域:
材料科学
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纳米技术
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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
·
2024
·
IF 4.1
Yu Gu,Jiahao Liu,Wei Gao,Meichen Liu,Chunwang Yi
The preparation of polyesteramides (PEAs) with regular block structure has long been a challenge, owing to the occurrence of the ester-amide exchange during the polymerization at high tempereture. In this work, we report a simple and green method to prepare polyamide 6 (PA6) based triblock PEA whose structure is poly(ε-caprolactone)-block-PA6-block-poly(ε-caprolactone) (PCL- b -PA6- b -PCL) using tetraphenyl tin as catalyst without solvent. The first segment PA6 was synthesized via cationic ring-opening polymerization (ROP) of ε-caprolactam (CPL), later, ROP of ε-caprolactone (CL) was involved to extend polycaprolactone (PCL) segments by using tetraphenyl tin as catalyst. By varying the proportion of CPL and CL, series PA6-based PEAs was prepared and characterized by gel permeation chromatography, 1 H, DOSY, and 13 C NMR. The results showed that PEA containing more proportion of CL presented a higher molecular weight with narrow polydisperse index. In particular, the lower water absorption and lower oligomers content infers that the PEA could have a prospective application in processing precision electronic devices.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2018
·Vol. 125
·期 1
·199-211
·
IF 1.515
Hao Fang,Yang Yongzhe,Xiong Wei,Liu Pingle,You Kuiyi,Luo He’an
Mesoporous SiO 2 –Al 2 O 3 supported Cr 2 O 3 catalysts were prepared by the sol–gel and impregnation methods. These catalysts were characterized and applied in cyclohexane nitrosation reaction. The effects of the preparation conditions and the catalyst deactivation were studied. The results show that 20% Cr 2 O 3 /SiO 2 –Al 2 O 3 catalyst calcined at 400 °C exhibits not only the larger surface area, smaller particle size, but also the larger amount of Cr 2+ and Brønsted acid sites. These catalysts show good catalytic performances in the cyclohexane nitrosation to ε-caprolactam and could be recycled for several times in this reaction system for the first time. The catalyst of Cr 2 O 3 /SiO 2 –Al 2 O 3 calcined at 400 °C gives 10.8% conversion with 79.9% selectivity to ε-caprolactam.
研究领域:
催化化学
·
材料科学
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产品关联
DOI
高影响因子
LANGMUIR
·
2024
·
IF 3.7
Shuwen Tan,Xiaojia Xu,Ting Zhang,Min Li,Xiaoyan Liu,Per M. Claesson,Yu Fang
Microgels have been widely used for stabilizing emulsions due to their softness and stimulus responsiveness. Although ultrastable emulsions have been prepared by microgel nanoparticles, the role of electrostatic interactions on emulsion stability is still a controversial topic and further investigation of the effect of microgel deformability is required. In the present study, neutral poly(N-vinylcaprolactam) (PVCL) and charged poly(N-vinylcaprolactam)-co-methacrylic acid (P(VCL-co-MAA)) microgels were synthesized and further used as emulsifiers to stabilizing emulsion. The P(VCL-co-MAA) microgel has a swelling ratio larger than that of the PVCL microgel in water. The nanomechanical properties of the microgels in water were characterized by atomic force microscopy with using the tip of different radii. The result reveals that the P(VCL-co-MAA) microgel is more deformable than the PVCL counterpart. Stability tests of the emulsions showed that below the volume phase transition temperature (VPTT) of the microgels, both microgel types can stabilize the emulsions under various conditions. Unexpectedly, most of the emulsions still remain stable above the VPTT. Further increasing the temperature to 60 °C, P(VCL-co-MAA) microgel emulsions remained stable at a pH value above the pKa of MAA while the emulsion was unstable below the pKa. However, phase separation occurs in PVCL microgel-stabilized emulsions at 60 °C. These results demonstrate that electrostatic repulsion and deformability of the microgels can enhance the emulsion stability, providing insights into the rational design and preparation of ultrastable Pickering emulsions.
研究领域:
材料科学
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化学工程
·
软物质物理
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产品关联
DOI
PubMed
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2017
·Vol. 19
·期 40
·27221-27232
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IF 4.123
Gehong Su,Tao Zhou,Xifei Liu,Yulin Zhang
In this study, temperature-dependent FTIR spectroscopy in combination with the perturbation–correlation moving-window (PCMW2D) technique and generalized two-dimensional (2D) correlation analysis was applied to investigate the phase transition mechanism of poly(N-vinylcaprolactam) (PVCL) hydrogel upon heating. In the conventional 1D FTIR spectra, the gradual dehydration of C–H groups, as well as the gradual dissociation of hydrogen bonds between CO groups and water molecules, was observed during phase transition. Moreover, we found that the rate at which water molecules were expelled out of the gel network during phase transition was changed to a sigmoid mode, rather than increasing linearly with increasing temperature. PCMW2D FTIR spectra revealed that the phase transition of PVCL hydrogel can be divided into two steps (named as I and II) upon heating, and we further determined the temperature regions of steps I and II to be 29.0–35.7 °C and 35.7–47.5 °C, respectively. Step I is the formation of hydrophobic domains in the gel, and step II is the chain collapse of the gel. Finally, with the help of generalized 2D correlation analysis, it was confirmed that the transformation of hydrogen bonds was the driving force of the hydrophobic domain formation process, while the hydrophobic interaction of C–H groups was the driving force for the chain collapse process. Combined with the obtained sequential orders of step I and step II, an integrated two-step phase transition mechanism of PVCL hydrogel upon heating was proposed.
研究领域:
材料科学
·
化学
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DOI
PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 98
·96237-96244
·
IF 3.289
Xiangxu Cui,Tingting Li,Shaowei Yao,Libao An,Yuqing Li,Zhi Zhou,Mengchao Guo,Zhiming Zhang
For comprehensive treatment of wastewater, an electrospun H4SiW12O40 (SiW12)/chitosan (CS)/polycaprolactam (PA6) sandwich nanofibrous membrane (SNM) with dual-functions of adsorption and photocatalysis was prepared to remove Cr(VI) and methyl orange (MO) from aqueous solution. The three layers of the SNM had good compatibility and thus no visible stratification phenomenon was observed in the SNM. Taking advantage of the merits of high porosity, good hydrophilicity, robust mechanical strength and superior water tolerance, the obtained SNM presented an excellent comprehensive performance with high adsorption capacity toward Cr(VI) (78.5 mg g−1), high photodegradation efficiency toward MO (96.7%) and good reusability. Based on the images of the SNM after Cr(VI) adsorption, the SiW12/PA6 layer (upper and bottom layer) was not affected in the adsorption process, which was consistent with our initial design. XPS analysis was carried out to investigate the mechanism of adsorption and photocatalysis. In the adsorption process, Cr(VI) was initially adsorbed on the CS/PA6 layer (intermediate layer), followed by the reduction of Cr(VI) to Cr(III) by the –NH2 of CS. The photocatalytic process was driven by the reductive pathway with faster degradation rate due to the electron donation from PA6 to SiW12. Although Cr(III) at the layer boundary was involved in the photocatalytic process, the photocatalytic activity of the SiW12/PA6 layer was almost not influenced. This work may provide a new and effective strategy to construct multifunctional nanofibrous membranes for the comprehensive treatment of wastewater.
研究领域:
环境科学
·
材料科学
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产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
·
2015
·Vol. 54
·期 3
·385-396
·
IF 3.83
Qiuwen Wang,Hui Tang,Peiyi Wu
Dynamic phase transition and self-assembly mechanism of thermosensitive poly(ethylene oxide)- b -poly( N -vinylcaprolactam) (PEO- b -PVCL) copolymer are explored deeply. A gradual dehydration process with predominated hydrophobic interactions among copolymer chains in the phase transition process distinguishes the copolymer from homopolymer. PVCL in the inner zone is restricted and counter-balanced by the PEO segments based on the sequence order of representative groups during the heating-cooling cycles. Remarkably, PEO shell experiences unusual hydration process, which is first discovered. This hydrophilic shell plays as water absorption sponge layer and captures expelled water from PVCL core, accompanied by gradient distribution of water existed in the assembly structures. Peculiarly, pseudo-linear changes of the integral area of free CO are presented compared with inflection point in the hydrated CO integral area, which propose that a part of hydrated CO forms incomplete dehydrated states. During the cooling process, perfect reversibility is observed without obvious hysteresis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54 , 385–396
研究领域:
高分子科学
·
物理化学
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产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2015
·
IF 3.942
Difan Li,Dan Mao,Jing Li,Yu Zhou,Jun Wang
Exploring environmentally friendly, efficient and recyclable heterogeneous catalysts for low-temperature liquid-phase organic reactions are important for the development of green and sustainable processes. In this work, we applied an in situ sulfonated polymeric solid acid H-PDVB-SO 3 H for catalyzing liquid-phase Beckmann rearrangements for the first time, with post-sulfonated sample and other various counterparts as control catalysts. H-PDVB-SO 3 H was prepared by copolymerization of divinylbenzene with sodium p -styrene sulfonate under solvothermal condition, followed by ion-exchanging to convert the polymer into proton form. It possessed a large surface area, plenty of mesopores and high sulfur content, and exhibited the high yield to ε-caprolactam (75%) with quite steady reusability in the heterogeneous Beckmann rearrangement of cyclohexanone oxime. The catalyst also showed good substrate compatibility with such a high reaction rate that the reaction time was as short as 1 h. No any co-catalysts or metals were used in the catalytic system, making the catalyst an environmentally friendly and efficient candidate for Beckmann rearrangements.
研究领域:
绿色化学
·
催化化学
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2022
·
IF 4.654
Cuiping Tang,Yanan Zhang,Deqing Liang
Adding hydrate inhibitors is an important method to prevent gas hydrates from blocking oil and gas pipelines and ground equipment. In this work, on the basis of polyvinyl caprolactam (PVCap), an ester group and a hydroxyl group were introduced into the molecular chain end of PVCap to synthesize a blocked modified inhibitor, Es-PVCap-OH. Fourier transform infrared spectroscopy, 1H NMR, and gel permeation chromatography methods were used to characterize PVCap and Es-PVCap-OH. The inhibition performance of Es-PVCap-OH for the formation of methane hydrate was studied and compared with that of the kinetic inhibitor PVCap. Powder X-ray diffraction, Raman spectroscopy, and cryogenic scanning electron microscopy (cryo-SEM) were used to characterize the microstructure of methane hydrate. The results showed that Es-PVCap-OH had better kinetic hydrate inhibitor performance and higher maximum subcooling than PVCap at the same concentration for methane gas hydrate formation. With 1 wt % Es-PVCap-OH solution, the induction time of hydrate formation increased by about 1400 min compared with that of the pure water system. Es-PVCap-OH selectively acts on specific hydrate crystal planes and affects the relative peak intensities of crystal planes. The addition of Es-PVCap-OH can substantially reduce the occupancy ratio of methane in the large cages of the hydrate lattice and change the morphology of the hydrate from submicron pores to a scaly cluster.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2020
·Vol. 55
·期 35
·16846-16859
·
IF 3.553
Zhou Quan,Yu Yueru,Liu Qi,Zhuang Yuxiao,Lv Yizhe,Song Ning,Ni Lizhong
In this study, a novel triblock copolymer poly(ε-caprolactam)-block-poly(dimethylsiloxane)-block-poly(ε-caprolactam) (PLC-b-PDMS-b-PLC) was synthesized by ring-opening polymerization. The approach of improving thermal and mechanical properties of thermosetting epoxy resin (ER) used methyl hexahydrophthalic anhydride as hardener and PLC-b-PDMS-b-PLC as modifier. The test results showed the chemical structure and molecular weight of PLC-b-PDMS-b-PLC can be controlled, and PLC-b-PDMS-b-PLC was self-assembled in the epoxy hybrid system to form nanophase separation structure. From the test of thermal and mechanical properties, it can be known that the amount of block in ER will affect the morphology and density of nanophase, thus affecting the toughness of the material. In the “soft-core hard-shell” nanodomain, the interaction of crystalline hard segments and non-crystalline PDMS soft segments overlapped adjacent stress fields, which helped the material absorb energy when subjected to external impact. The fracture toughness and impact strength of the modified resin were increased by up to 1.52 and 2.19 times compared to neat ER, respectively.
研究领域:
材料科学
·
高分子化学
·
热力学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）