检索结果-南通市图书馆

Readily Prepared and Tunable Ionic Organocatalysts for Ring-opening Polymerization of Lactones

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2019年第12期37卷 1205-1214,I0005页

作者： Zhuo-Lun Jiang Jun-Peng zhao guang-zhao zhang Faculty of Materials Science and Engineering South China University of Technology

Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization(ROP)of lactones,includingδ-valerolactone,ε-caprolactone,andδ-*** catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a(thio)urea at elevated temperature under vacuum,and used in cooperation with an alcoholic *** performance of the catalyst is readily adjusted and optimized through variation of the(thio)urea precursor,catalyst composition,and reaction ***-derived catalysts are generally superior to thiourea-derived *** with proper N-substituents,the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification,even at high monomer conversion and/or substantially extended reaction *** addition to acidity,structural symmetry of the urea also proves decisive for the catalytic activity,which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.

关键词： Organocatalytic polymerization Ring-opening polymerization Polyester

Modulation of Self-healing of Polyion Complex Hydrogel by Ion-specific Effects

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2016年第6期29卷 725-728,I0002页

作者： Hui-li Liu guang-ming Liu guang-zhao zhang DepartmentofChemicalPhysics HefeiNationalLaboratoryforPhysicalSciencesattheMicroscaleUniversityofScienceandTechnologyofChinaHefei230026China FacultyofMaterialsScienceandEngineering SouthChinaUniversityofTechnologyGuangzhou510640China

We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the self- healing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.

关键词： Polyelectrolyte hydrogel Self-healing Ion-specific effects Mechanical property Counterions

Progress in Polymer-Ceramic Hybrid Antifouling Coatings

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2023年第7期41卷 995-1001页

作者： Zhen-Qiang zhang Yin-Jie Huang Chun-Feng Ma guang-zhao zhang Faculty of Materials Science and Engineering South China University of TechnologyGuangzhou510640China

Simultaneous realization of superior mechanical and antifouling properties is critical for a coating. The use of stereoscopic polysiloxanes in place of linear polysiloxanes to fabricate antifouling coatings can combine properties of organic and inorganic materials, i.e., they can exhibit both high hardness and wear resistance from inorganic components as well as the flexibility and tunability from organic components. This strategy is used to prepare hard yet flexible antifouling coatings or polymer-ceramic hybrid antifouling coatings. In this mini-review, we report the recent advances in this field. Particularly, the effects of stereoscopic polysiloxane structures on their mechanical and antifouling properties are discussed in detail.

关键词： Antifouling coating Organic-inorganic hybrid Sol-gel Hard yet flexible

Efficient design method for cell allocation in hybrid CMOS/nanodevices using a cultural algorithm with chaotic behavior

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2016年第2期11卷 115-123页

作者： Zhong-Liang Pan Ling Chen guang-zhao zhang School of Physics and Telecommunications Engineering South China Normal University Guangzhou 510006 China Department of Electronics and Communications Sun Yat-sen University Guangzhou 510275 China

The hybrid CMOS molecular （CMOL） circuit, which combines complementary metal-oxide- semiconductor （CMOS） components with nanoscale wires and switches, can exhibit significantly improved performance. In CMOL circuits, the nanodevices, which are called cells, should be placed appropriately and are connected by nanowires. The cells should be connected such that they follow the shortest path. This paper presents an efficient method of cell allocation in CMOL circuits with the hybrid CMOS/nanodevice structure; the method is based on a cultural algorithm with chaotic behavior. The optimal model of cell allocation is derived, and the coding of an individual represent- ing a cell allocation is described. Then the cultural algorithm with chaotic behavior is designed to solve the optimal model. The cultural algorithm consists of a population space, a belief space, and a protocol that describes how knowledge is exchanged between the population and belief spaces. In this paper, the evolutionary processes of the population space employ a genetic algorithm in which three populations undergo parallel evolution. The evolutionary processes of the belief space use a chaotic ant colony algorithm. Extensive experiments on cell allocation in benchmark circuits showed that a low area usage can be obtained using the proposed method, and the computation time can be reduced greatly compared to that of a conventional genetic algorithm.

关键词： nanodevices structure design cell allocation CMOS technology cultural algorithms

Organocatalytic Copolymerization of Mixed Type Monomers

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2017年第5期35卷 581-581,582-601页

作者： Qi-lei Song Shuang-yan Hu 赵俊鹏 guang-zhao zhang Faculty of Materials Science and Engineering South China University of Technology

Triggered by environmental concerns and the rising demands for metal-free polymers in e.g. bio-related and microelectronic applications, studies on organocatalytic polymerization have been launched and developed unprecedentedly during the last 15 years. A wide range of organic molecules are now available in polymer chemists＇ toolbox to choose from as catalysts for polymerization of （hetero）cyclic and polar vinyl monomers. Apart from the intrinsic merits such as lower toxicity and better solubility compared with （transition） metal catalysts/initiators, organocatalysts have also shown, in many cases, excellence to achieve high polymerization rates and/or good control （selectivity）. In addition, particular natures and catalytic/activating mechanisms of organocatalysts have led to new opportunities for rational design and efficient synthesis of macromolecular architectures, i.e. chain structures, topological structures and functionalities. This mini-review is specially themed on pathways to construct copolymer chain structures by organocatalytic copolymerization of mixed type monomers （comonomers bearing different polymerizing moieties） and will be sectioned by different comonomer combinations, including cyclic monoesters of different sizes, cyclic monoesters and lactides, cyclic esters and cyclic carbonates or epoxides, heterocycles and vinyl monomers.

关键词： Chain structure Copolymer Organocatalytic polymerization

Cultural Algorithm for Minimization of Binary Decision Diagram and Its Application in Crosstalk Fault Detection

在线全文

学校读者我要写书评

暂无评论

International Journal of Automation and computing 2010年第1期7卷 70-77页

作者： Zhong-Liang Pan Ling Chen guang-zhao zhang Department of Electronics South China Normal University Guangzhou 510006 PRC Department of Electronics and Communications Sun Yat-sen University Guangzhou 510275 PRC

The binary decision diagrams （BDDs） can give canonical representation to Boolean functions; they have wide applications in the design and verification of digital systems. A new method based on cultural algorithms for minimizing the size of BDDs is presented in this paper. First of all, the coding of an individual representing a BDDs is given, and the fitness of an individual is defined. The population is built by a set of the individuals. Second, the implementations based on cultural algorithms for the minimization of BDDs, i.e., the designs of belief space and population space, and the designs of acceptance function and influence function, are given in detail. Third, the fault detection approaches using BDDs for digital circuits are studied. A new method for the detection of crosstalk faults by using BDDs is presented. Experimental results on a number of digital circuits show that the BDDs with small number of nodes can be obtained by the method proposed in this paper, and all test vectors of a fault in digital circuits can also be produced.

关键词： Digital circuits binary decision diagrams (BDDs) cultural algorithms variable order fault detection

在线全文

学校读者我要写书评

暂无评论

杂化共聚反应

高分子学报 2018年第6期28卷 668-673页

作者：张广照华南理工大学材料科学与工程学院广州510640

杂化共聚是具有不同可聚合基团的2种或2种以上单体的共聚合反应.它颠覆了传统共聚的概念,因为传统共聚的单体必须具有相同的可聚合基团.显然,杂化共聚为高分子合成提供了新路径.然而,由于具有不同可聚合基团的单体聚合机理不同、反应活... 详细信息

杂化共聚是具有不同可聚合基团的2种或2种以上单体的共聚合反应.它颠覆了传统共聚的概念,因为传统共聚的单体必须具有相同的可聚合基团.显然,杂化共聚为高分子合成提供了新路径.然而,由于具有不同可聚合基团的单体聚合机理不同、反应活性相差大,杂化共聚十分具有挑战性.20世纪80年代,先后出现了自由基开环杂化共聚和两性离子杂化共聚.近年来,随着有机小分子引发/催化的发展,人们创立了阴离子杂化共聚和阳离子杂化共聚.本文将介绍杂化共聚的进展情况.

关键词：杂化共聚阴离子聚合阳离子聚合自由基开环聚合有机小分子催化

NOVEL SYNTHESIS OF LONG MULTI-BLOCK HETEROPOLYMER CHAINS WITH AN ORDERED SEQUENCE AND CONTROLLABLE BLOCK LENGTHS

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2001年第5期19卷 451-454页

作者： Chi Wu Zuo-wei Xie guang-zhao zhang Guo-fu Zi Department of Chemistry, The Chinese University of Hong Kong Shatin, N.T., Hong Kong China Chinese Univ Hong Kong Dept Chem Shatin Hong Kong Peoples R China

It had very long been a dream in polymer science to synthesize long multi-block polymer chains with an orderedchain sequence and controllable block lengths. Using ionic or living free radical polymerization or furnishing each end ofpolymer blocks with a reactive functional group, one can only prepare heteropolymer chains with few long blocks, such asdiblock and triblock copolymers. The most plausible result so far was a pentablock copolymer. Recently, using a combinationof polymer physics and synthetic chemistry, we have invented self-assembly assisted polycondensation (SAAP). Thiscommunication reports the results of using this novel. method to connect 10-100 triblock polymer chains together to formlong multi-block heteropolymer chains with an ordered sequence and controllable block lengths.

关键词： multi-block copolymer self assembly self assembly assisted polypolymerization novel polymer synthesis

New Insights into Folding Kinetics of α,ω Dye-Functionalized Poly(N-isopropylacrylamide)

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2018年第6期31卷 789-798,733,734页

作者： Xiao-yan Wang Hai-yan Fan Xiao-dong Ye Shi-lin Liu guang-zhao zhang Hefei National Laboratory for Physical Sciences at the Microscale Department of Chemical PhysicsUniversity of Science and Technology of China Hefei 230026 China CAS Key Laboratory of Soft Matter Chemistry University of Science and Technology of ChinaHefei 230026 China Faculty of Materials Science and Engineering South China University of Technology Guangzhou 510640 China

Two narrowly-distributed poly(N-isopropylacrylamide)(PNIPAM) samples were prepared via atom transfer radical polymerization (ATRP) with a novel dansyl functionalized initiator. The other end of the PNIPAM was functionalized by dabcyl group via click reaction. From the static fluorescence measurements, the fluorescence intensity of dansyl group and energy transfer efficiency between dansyl and dabcyl groups increased when the temperature increased from 36 °C to 45 °C, indicating that the microenvironment surrounding dansyl became hydrophobic and the distance between dansyl and dabcyl decreased. The kinetics of the conformational change of the dye-labeled PNIPAM was studied by a home-made laser-induced temperature jump device with fluorescent measurement. Our results revealed that the characteristic transition time was 3.8 and 5.8 ms for PNIPAM with degrees of polymerization of 85 and 142, respectively, indicating that the characteristic transition time was related to the chain length. Besides, characteristic transition time for the change of the energy transfer efficiency was 2.9 ms for PNIPAM with the degree of polymerization of 85, suggesting that the energy transfer efficiency change was faster than the fluorescence intensity change of dansyl group.

关键词： Fluorescence Laser-induced temperature jump Phase transition Poly(N-isopropylacrylamide)