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Science China Chemistry 2018年第2期61卷 141-142页

作者： yongfeng zhou School of Chemistry & Chemical Engineering State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University

Novel macromolecular architectures with well-defined compositions and structures are of particular interest and the synthesis and self-assembly of those polymers have been an important research topic in polymer scienc... 详细信息

关键词：聚合物不对称分子平台大楼射击体系结构

Phase diagrams, mechanisms and unique characteristics of alternating-structured polymer self-assembly via simulations

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Science China Chemistry 2019年第2期62卷 226-237页

作者： Shanlong Li Chunyang Yu yongfeng zhou School of Chemistry & Chemical Engineering State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University

Alternating-structured polymers(ASPs), like alternating copolymers, regular multiblock copolymers and polycondensates, are very important polymer structures with broad applications in photoelectric materials. However, their self-assembly behaviors,especially the self-assembly of alternating copolymers, have not been clearly studied up to now. Meanwhile, the unique characteristics therein have not been systematically disclosed yet by both experiments and theories. Herein, we have performed a systematic simulation study on the self-assembly of ASPs with two coil alternating segments in solution through dissipative particle dynamics(DPD) simulations. Several morphological phase diagrams were constructed as functions of different impact parameters. Diverse self-assemblies were observed, including spherical micelles, micelle networks, worm-like micelles, disklike micelles, multimicelle aggregates, bicontinuous micelles, vesicles, nanotubes and channelized micelles. Furthermore, a morphological evolutionary roadmap for all these self-assemblies was constructed, along with which the detailed molecular packing models and self-assembly mechanisms for each aggregate were disclosed. The ASPs were found to adopt a folded-chain mechanism in the self-assemblies. Finally, the unique characteristics for the self-assembly of alternating copolymers were revealed especially, including(1) ultra-fine and uniform feature sizes of the aggregates;(2) independence of self-assembled structures from molecular weight and molecular weight distribution;(3) ultra-small unimolecular aggregates. We believe the current work is beneficial for understanding the self-assembly of alternating structured polymers in solution and can serve as a guide for the further experiments.

关键词： alternating-structured polymer self-assembly dissipative particle dynamics simulations phase diagram

Drug release property of a pH-responsive double-hydrophilic hyperbranched graft copolymer

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Science China Chemistry 2009年第10期52卷 1703-1710页

作者： SUN XiaoYi zhou yongfeng YAN DeYue College of Chemistry and Chemical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

In this paper, we report the synthesis and self-assembly of double-hydrophilic hyperbranched graft copolymers of HPG-g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG-g-PDMAEMA graft copolymers through atom transfer radical polymerization (ATRP) of DMAEMA monomers. The molecular structures were studied by 1H NMR and GPC. The pyrene-based fluorescent probe method, 1H NMR and DLS were used to study the self-assembly behavior of HPG-g-PDMAEMA. The drug loading and pH-responsive release properties of HPG-g-PDMAEMA were also investigated by using coumarin 102 as a model drug. The results show that the HPG-g-PDMAEMA micelles can continuously release and re-encapsulate coumarin 102 as the pH continuously changes from 11.5 to 2.5; however, this process is not totally reversible.

关键词： hyperbranched polymers double-hydrophilic copolymer polyglycerol ATRP drug delivery

Preparation of polystyrene-grafted titanate nanotubes by in situ atom transfer radical polymerization

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Science China Chemistry 2009年第3期52卷 344-350页

作者： GAO Yuan zhou yongfeng YAN DeYue School of Chemistry and Chemical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

This work successfully prepared nanohybrids by in situ atom transfer radical polymerization (ATRP) of styrene from titanate nanotubes (TNTs). Fourier-transform infrared (FT-IR), pronton nuclear magnetic resonance spectroscopy (1H NMR), and thermal gravimetric analysis (TGA) were used to verify the successful graft of polystyrene (PS) chains from TNTs. Transmission electron microscopy (TEM) dis-played that the obtained PS-g-TNTs nanohybrids had a core-shell structure of TNT core and PS shell. The grafted PS content was well controlled and increased with increasing of the monomer/initiator ratio. Further copolymerization of tert-butyl acrylate (tBA) from the surface of PS-g-TNTs was studied, illus-trating the "living" characteristics of the surface-induced ATRP method used in this work.

关键词： titanate nanotubes atom transfer radical polymerization polystyrene surface modification

Crosslinked chitosan nanofiber mats fabricated by one-step electrospinning and ion-imprinting methods for metal ions adsorption

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Science China Chemistry 2016年第1期59卷 95-105页

作者： Yan Li Jie Zhang Cong Xu yongfeng zhou School of Materials Science and Engineering Tongji University School of Chemistry and Chemical Engineering Shanghai Jiao Tong University

The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were fabricated by one-step electrospinning and ion-imprinting methods and their application as adsorbents for metal ions was also *** resulting chitosan nanofiber mats were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermal gravimetric analysis(TGA).The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were used as adsorbents for the removal of Pb(Ⅱ)ions from aqueous or acid *** effects of p H values,contact time,content of crosslinker(glutaraldehyde)on Pb(Ⅱ)ions adsorption were *** results indicated that the Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats had the highest adsorption capacity of 110.0 mg/g at p H *** kinetic study demonstrated that the adsorption of Pb(Ⅱ)ions followed the pseudo-second-order *** equilibrium isotherm data showed that the Langmuir model was the most suitable for predicting the adsorption isotherm of the studied *** Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats had good adsorption selectivity,which illustrates the equilibrium adsorption capacity in the order of Pb(Ⅱ)>Cu(Ⅱ)>Zn(Ⅱ)>Cd(Ⅱ)>Ni(Ⅱ).The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were stable and had good reuse ability.

关键词： chitosan one-step electrospinning ion-imprinting Pb(II) ion adsorption

Synthesis of cationic hyperbranched multiarm copolymer and its application in self-reducing and stabilizing gold nanoparticles

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Science China Chemistry 2010年第5期53卷 1113-1120页

作者： Zhai, Shuo Hong, HaiYan zhou, yongfeng Yan, DeYue State Key Laboratory of Metal Matrix Composites College of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China

A novel hyperbranched multiarm copolymer of HBPO-star-PDEAEMA with a hydrophobic poly(3-ethyl-3-(hydroxymethyl) oxetane)(HBPO) core and many cationic poly(2-(N,N-diethylamino) ethyl methacrylate)(PDEAEMA) arms has been synthesized through an atom transfer radical polymerization(ATRP) method,and been applied to spontaneously reduce and stabilize gold nanoparticles(AuNPs) in water without other additional *** size of the nanoparticles could be effectively controlled at about 4 nm,and the nanoparticles are extremely stable in solution without aggregation even for one *** was found that solution pH and the molar ratio of N/Au have certain effects on the size and stability of *** work provides a simple method for the synthesis of uniform and highly stable AuNPs.

关键词： gold nanoparticles hyperbranched polymers self-reduction stabilization

Effect of Milling Time on the Microstructure and Tensile Properties of Ultrafine Grained Ni–SiC Composites at Room Temperature

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Journal of Materials Science & Technology 2015年第9期31卷 923-929页

作者： Hefei Huang Chao Yang Massey de los Reyes yongfeng zhou Long Yan Xingtai zhou Shanghai Institute of Applied Physics Chinese Academy of Sciences Institute of Materials Engineering Australian Nuclear Science and Technology Organisation

Bulk metallic nickel-silicon carbide nano-particle （Ni-SiCNp） composites, with milling time ranged from 8 to 48 h, were prepared in a planetary ball mill and sintered using a spark plasma sintering （SPS） furnace. The microstructure of the Ni-SiCnp composites was characterized by transmission electron microscopy （TEM） and their mechanical properties were investigated by tensile measurements. The TEM results showed well-dispersed SiCNp particles, either within the matrix, between twins or along grain boundaries （GB）, as well as the presence of stacking faults and twin structures, characteristics of materials with low stacking fault energy. Dislocation lines were also observed to interact with the SiCNp which were plastically nondeformable. A synergistic relationship existed between Hall-Perch strength- ening and dispersion strengthening mechanisms, which was shown to greatly influence the mechanical properties of the Ni-SiCNp composites. Both the maximum yield and tensile strengths were found in the Ni-SiCNp composite with a milling time of 48 h, whereas the increased rate of strengths drastically decreased in material milled above 8 h due to the significant SiCNp agglomeration. The ball milling process resulted in the formation of nano-scale, ultra-fine grained （UFG） Ni-SiCNp composites when the milling time was extended for longer periods, greatly strengthening these materials. The sharp decrease in elongation percentages, however, should be comprehensively considered before irrevers- ible inelastic deformation.

关键词： Ni-SiCNp compositeMechanical alloyingSpark plasma sinteringTransmission electron microscopyTensile testUltra-fine grained (UFG)

Synthesis of Polyethylenes with In-Chain Isolated Carbonyls from CO_(2)and Ethylene via a Tandem Photoreduction/Polymerization Protocol

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CCS Chemistry 2024年第6期6卷 1591-1599页

作者： Fulin zhou Haojie Dai Shan Tang yongfeng zhou Frontiers Science Center for Transformative Molecules Shanghai Key Laboratory for Molecular Engineering of Chiral DrugsSchool of Chemistry and Chemical EngineeringShanghai Jiao Tong UniversityShanghai 200240

Aiming at accessing polyethylene-bearing in-chain degradable functionality,copolymerization of carbon dioxide(CO_(2))with ethylene has long been recognized as a significant but highly challenging ***,most trials have resulted in ethylene homopolymerization because of the endothermic property and high energy barriers of CO_(2)insertion during polymer chain *** we report an unprecedented tandem reaction protocol for the synthesis of polyethylenes with in-chain carbonyls from CO_(2)and ethylene by the combination of photocatalytic CO_(2)reduction and palladium-catalyzed coordination/insertion *** protocol provides an easy way to adjust the carbonyl content(from 0.13 to 12 mol%)and insertion selectivity(up to 99%isolated carbonyls)of the polyethylene copolymers,which enables the polymers tomaintain the main properties of highdensity polyethylene and simultaneously endows them with good *** addition,besides apolar polyethylene copolymers,polar-functionalized polyethylenes with in-chain isolated carbonyls can also be synthesized from CO_(2),ethylene and a polar monomer using the same *** believe our present work sheds new light on the synthesis of degradable polyethylenes by employing CO_(2)as a green carbonyl source.

关键词： carbon dioxide coordination polymerization polyethylene photoreduction photodegradation

Computer simulation studies of the influence of side alkyl chain on glass transition behavior of carbazole trimer

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Science China Chemistry 2017年第3期60卷 377-384页

作者： Chunyang Yu Li Ma Wei Huang yongfeng zhou Jingui Qin Deyue Yan State Key Laboratory of Metal Matrix Composites School of Chemistry & Chemical EngineeringShanghai Jiao Tong University Department of Chemistry Wuhan University

In this work,all-atom molecular dynamics simulations were employed to study the influence of the side alkyl chain on glass transition behavior of several carbazole trimers(CT) in a temperature range from 423 to 183 *** glass transition temperatures were obtained from the break in the slope of the volume-temperature curves and found to agree with the experimental *** short time dynamics of four CT molecules were probed by usingvelocity autocorrelation functions and mean-square *** current studies showed that the dynamics of CT systems can be easily interpreted through the cage ***,the investigation of the torsional autocorrelation function and P_(2-state)/P_(3-state) functions showed that the rotational barriers of side chains can slow down the conformational relaxation and lead to stronger temperature dependence of conformational *** relaxation time,characteristic time of P_(2-state)(t) and P_(3-state)(t) functions were all found to have Arrhenius-type temperature dependence.

关键词： carbazole trimer molecular dynamics simulation glass transition relaxation time

Layered double hydroxide coatings on magnesium alloys: A review

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Journal of Materials Science & Technology 2018年第9期34卷 1455-1466页

作者： Lian Guo Wei Wu yongfeng zhou Fen Zhang Rongchang Zeng Jianmin Zeng College of Material Science and Engineering Shandong University of Science and Technology Ministry-Province Jointly-constructed Cultivation Base for State Key Laboratory of Processing for Non-ferrous Metal and Featured Materials Guangxi University

Layered double hydroxides（LDHs） as a class of anionic clays have extensive applications due to their unique structures. Nowadays, the emphasis is laid on the development of LDH coatings for corrosion resistance and medical applications. Thus, this review highlights synthetic methods of LDH coatings and LDH-based composite coatings on magnesium alloys. Special attention is focused on self-healing,biocompatible and self-cleaning LDH-based composite coatings on magnesium alloys.

关键词： Layered double hydroxides Magnesium alloys Corrosion resistance Self-healing Biocompatibility Self-cleaning