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Synthesis, thermomorphic characteristics, and fluorescent properties of poly[2,7-(9,9-dihexylfluorene)]-block-poly(N-isopropylacrylamide) -block-poly(N-hydroxyethylacrylamide) rod-coil-coil triblock copolymers

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Soft Matter 2009年第19期5卷 3761-3770页

作者： Lin, Sung-Tso Fuchise, Keita Chen, Yougen Sakai, Ryosuke Satoh, Toshifumi Kakuchi, Toyoji Chen, Wen-Chang Institute of Polymer Science and Engineering National Taiwan University Taipei 10617 Taiwan Division of Biotechnology and Macromolecular Chemistry Graduate School of Engineering Hokkaido University Sapporo 060-8628 Japan Department of Chemical Engineering National Taiwan University Taipei 10617 Taiwan

New thermoresponsive conjugated rod-coil-coil triblock copolymers were successfully synthesized from terminal azido functionalized poly(N- isopropylacrylamide)-b-poly(N-hydroxyethylacrylamide) (PNIPAAm-b-PHEAA) and alkynyl functionalized polyfluorene (PF) via a click reaction. The azido functionalized PNIPAAm-b-PHEAA copolymers with different block ratio was prepared by atom transfer radical polymerization from an initiator bearing the azide group, whereas alkynyl functionalized PF was synthesized by Suzuki coupling reaction. The lower critical solution temperature (LCST) of the block copolymers increased with an enhanced hydrophilic PHEAA block ratio, since the longer PHEAA segment facilitated the copolymer chains to stretch at an elevated temperature. The micelles of PNIPAAm-b-PHEAA with different block ratio changed into spheres, aggregate spheres, vesicles, and wormlike micelles as the temperature was increased, due to the variation on the hydrophilic/hydrophobic characteristic of PNIPAAm. However, the micellar morphologies became worms, bundles of wormlike micelles, and hollow tubes in the triblock PF-b-PNIPAAm-b-PHEAA, which were probably induced by the π-π interaction among the fluorene segments. The variation of the micelle morphology with temperature was consistent from the results of transmission electron microscopy, atomic force microscopy, and dynamic light scattering. Also, the micelle morphologies of PF-b-PNIPAAm-b-PHEAA showed a thermoreversible property based on its LCST. The photoluminescence characteristics behaved as an on/off fluorescence indicator of temperature, showing an "on-off-on" profile at an elevated temperature in water at a higher block ratio of PNIPAAm and switching to "on-off" as the block ratio of PNIPAAm decreased. The present study suggests that the PF-b-PNIPAAm-b-PHEAA copolymers have tunable morphologies and could be potentially used as thermoresponsive sensory materials. © 2009 The Royal Society of Chemistry.

关键词： Block copolymers

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Wrinkling modes of graphene oxide assembled on curved surfaces

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Nano Research 2023年第2期16卷 1801-1809页

作者： Kaiwen Li Zhanpo Han Lidan Wang Jiaqing Wang Chuanwei Zhang Jiahao Lin Shiyu Luo Li Peng Wenzhang Fang Yingjun Liu Ziliang Wu Yeqiang Tan Chao Gao Zhen Xu MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringKey Laboratory of Adsorption and Separation Materials&Technologies of Zhejiang ProvinceZhejiang UniversityHangzhou 310027China State Key Laboratory of Bio-Fibers and Eco-Textiles Collaborative Innovation Center of Marine Biobased Fiber and Ecological Textile TechnologySchool of Materials Science and EngineeringQingdao UniversityQingdao 266071China MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan 030000China

Assembling two-dimensional(2D)sheets into macroscopic three-dimensional(3D)forms has created a promising material family with rich *** wrinkles are intrinsic features of 2D sheets in their 3D ***,the precise wrinkling modulation optimizes the transition of outstanding properties of 2D sheets to expected performances of assembled materials and dominates their fabrication *** wrinkling evolution of 2D sheets assembling onto flat surfaces has been extensively understood,however,the wrinkling behaviors on the more generally curved surface still remain ***,we investigate the wrinkling behaviors of graphene oxide sheets assembled onto curved surfaces and reveal the selection rule of wrinkling modes that determined by the curvature mismatch between 2D sheets and target *** uncover that three wrinkling modes including isotropic cracked land,labyrinth,and anisotropic curtain phases,respectively emerge on flat,spherical,and cylindrical surfaces.A favorable description paradigm is offered to quantitatively measure the complex wrinkling patterns and assess the curvature mismatch constraint underlying the wrinkling mode *** research provides a general and quantitative description framework of wrinkling modulation of 2D materials such as high performance graphene fibers,and guides the precise fabrication of particles and functional coatings.

关键词： two-dimensional(2D)sheets three-dimensional(3D)assembles curved surfaces wrinkling modes selection curvature mismatch constraint wrinkling modulation

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Effects of Processing Parameters on Mechanical Properties and Structure of Banana Fiber-Reinforced Composites

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Journal of Renewable Materials 2018年第6期6卷 662-670页

作者： Dan-Thuy Van-Pham Minh Tri Nguyen Chanh-Nghiem Nguyen Thi Truc Duyen Le Thi Yen Nhu Pham Khai Thinh Nguyen Yukihiro Nishikawa Qui Tran-Cong-Miyata Department of Chemical Engineering Can Tho UniversityCan Tho CityViet Nam Department of Automation Technology Can Tho UniversityCan Tho CityViet Nam Department of Macromolecular Science and Engineering Graduate School of Science and TechnologyKyoto Institute of TechnologyMatsugasakiSakyo-kuKyoto 606-8585Japan

The mechanical properties of unidirectional natural fiber-reinforced composites are generally affected by several processing parameters during compression *** study investigates the effects of processing temperature,time,and pressure on the tensile and flexural properties of acrylonitrile butadiene styrene reinforced by banana fibers.X-ray CT imaging was employed to find the relationship between the mechanical properties and structure of the processed ***,the water absorption of composites was observed and the way in which the mechanical properties evolved after water absorption was *** tensile and flexural properties of the unidirectional banana fiber-reinforced composite were found to be inversely proportional to the *** addition,high-pressure compression molding might result in cracks and floating fibers that would significantly reduce its mechanical *** composite with the highest strength,smallest porosity and lowest water absorption was optimally prepared at T=170℃,t=20 min,and P=100 kg cm^-2.

关键词： Banana fiber composite compression molding porosity X-ray CT

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A Mini Review on Nanocarbon-Based 1D Macroscopic Fibers:Assembly Strategies and Mechanical Properties

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Nano-Micro Letters 2017年第4期9卷 175-192页

作者： Liang Kou Yingjun Liu Cheng Zhang Le Shao Zhanyuan Tian Zengshe Deng Chao Gao Shaanxi Coal and Chemical Technology Institute Co. Ltd MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua University

Nanocarbon-based materials, such as carbon nanotubes(CNTs) and graphene have been attached much attention by scientific and industrial community. As two representative nanocarbon materials, one-dimensional CNTs and twodimensional graphene both possess remarkable mechanical properties. In the past years, a large amount of work have been done by using CNTs or graphene as building blocks for constructing novel, macroscopic, mechanically strong fibrous materials. In this review, we summarize the assembly approaches of CNT-based fibers and graphene-based fibers in chronological order, respectively. The mechanical performances of these fibrous materials are compared, and the critical influences on the mechanical properties are discussed. Personal perspectives on the fabrication methods of CNT-and graphene-based fibers are further presented.

关键词： One dimensional Macroscopic architectures Carbon nanotubes Graphene fibers Assembly strategies Mechanical performance

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Structural modification of carbon black for improving the dielectric performance of epoxy based composites

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Advanced Industrial and engineering Polymer Research 2018年第1期1卷 111-117页

作者： Wang, Xin Li, Zewei Chen, Zhiwu Zeng, Lanying Sun, Luyi School of Materials Science and Engineering South China University of Technology Guangzhou China Polymer Program Institute of Materials Science and Department of Chemical & Biomolecular Engineering University of Connecticut Storrs CT United States

To explore a feasible strategy for improving the dielectric properties of carbon black (CB)/epoxy composites, CB@TiO2 core-shell particles and CB-SiO2 hybrid particles were prepared and incorporated into epoxy. The microstructures of CB, CB@TiO2, and CB-SiO2 particles, as well as the dielectric properties of their epoxy-based composites were investigated. The results showed that the composites containing CB-SiO2 hybrid particles possessed a higher dielectric constant than the ones containing pristine CB. The dielectric constant of the composite with 20.0 vol% CB-SiO2 reached 52.68 (1 kHz), which was ca. 4 times greater than that of the one containing 20.0 vol% pristine CB. Meanwhile, the composites containing CB@TiO2 core-shell particles exhibited suppressed values of dielectric loss. The permittivity of the composite with 20.0 vol% CB@TiO2 reached 19.52 (1 kHz), while its dielectric loss remained low (0.047 at 1 kHz). These results indicated that the dielectric properties of epoxy composites could be enhanced with the introduction of modified fillers. © 2018 Kingfa SCI. & TECH. CO., LTD.

关键词： Carbon black

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Nonlinear viscoelasticity of native and engineered ligament and tendon

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2010 Annual Conference on Experimental and Applied Mechanics

作者： Jinjin, Ma. Arruda, Ellen M. Department of Mechanical Engineering University of Michigan United States Department of Biomedical Engineering University of Michigan United States Macromolecular Science and Engineering Program University of Michigan United States

ISBN: (纸本)9781441994974

Ligaments and tendons are non-linear viscoelastic materials and their response functions are typically assessed using creep and stress relaxation tests. Non-linear viscoelastic models such as multiple Maxwell elements in parallel and the quasilinear viscoelastic model (QLV) used to capture the non-linear viscoelastic response of ligaments and tendons frequently employ multiple relaxation time constants determined from curve-fitting the entire available data set and generally lack a clear physiological relevance. Uniaxial load-unload tension tests on ligament and tendon also manifests the viscoelastic response and such experiments suggest that the bulk of the non-linearity in the response of these soft tissues is in the elasticity. We propose physiologically relevant nonlinear viscoelastic models in which the response of the main structural proteins in ligament and tendon (e.g. collagen and elastin) are described using non-linear elasticity. Our approach using a three-element, non-linear solid micromechanical model captures this viscoelastic response in load-unload, stress relaxation and creep with a limited number of physically meaningful parameters. Previous research also shows different viscoelastic responses between native tendon and ligaments. In our model, by varying the properties of the non-linear springs, we are able to capture the differences in the viscoelastic responses of ligaments verses tendon. We will demonstrate the capabilities of our model by comparing to the experimental results from testing native and engineered ligament and tendon. ©2010 Society for Experimental Mechanics Inc.

关键词： Tendons

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Probing the effects of external species on poly(acrylate acid) chain dynamics by using cationic AIE-active fluorophore

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science China Chemistry 2016年第2期59卷 218-224页

作者： Junfeng Niu Yuan Gao Yuru You Yinbang Zhu Jingzhi Sun Ben Zhong Tang School of Biological and Chemical Engineering Zhejiang University of Science & Technology Hangzhou 310023 China Key Laboratory of Macromolecular Synthesis and Functionalization Ministry of Education Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China Department of Chemistry Institute for Advanced Study Division of Biomedical Engineering Division of Life Science State Key Laboratory of Molecular Neuroscience and Institute of Molecular Functional Materials the Hong Kong University of Science and Technology Kowloon Hong Kong China

We report here our results on the investigation of the chain dynamics of poly(acrylic acid) in aqueous solution. The concentration of poly(acrylic acid) was approximately 3.8×10^(-4) mol/L, two orders of magnitude higher than that reported in the literature. The p H value of the solution was 3.9, and the hydrogen bonds between the intrinsic and ionized carboxylic acid groups formed dynamic networks, which captured aggregation-induced emission-active molecules(a tetra-quaternary ammonium modified tetraphenylethene derivative) inside the polymer coils and induced fluorescence emission. The hydrogen bonds can be classified as intra- or intermolecular; both can be probed based on the emission change of the tetra-quaternary ammonium modified tetraphenylethene probes. The effects of different external stimuli on the polymer chain dynamics were investigated using different metal cations(including Na^+, Li^+, Zn^(2+), Ni^(2+), Ca^(2+), and Co^(2+)), different cation concentrations(1×10^(-6) to 4×10^(-4) mol/L), different poly(acrylic acid) molecular weights(5, 240, and 450 k Da), and different copolymers. The experimental results indicate that the long poly(acrylic acid) chains(high molecular weight) tend to form dense globular coils and exclude the probe molecules outside, which are robust and unsusceptible to water-soluble metal cations. However, the shorter poly(acrylic acid) chains tend to form intermolecular hydrogen bonds, which are helpful in capturing more probe molecules inside the networks, thus inducing stronger emission. Because of the dual functions of forming hydrogen bonds with carboxylic groups and acting as an acceptor of protons from the carboxylic acid group to form cationic species, copolymerization with acrylate amide [poly(acrylic acid)-co-poly(acrylamide)] can greatly affect the chain dynamics of poly(acrylic acid) segments, which is reflected by the drastically decreased emission intensity from the fluorescent probes.

关键词： polymer dynamics concentrate solution aggregation-induced emission metal cation hydrogen bonding.

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Carbon-supported layered double hydroxide nanodots for efficient oxygen evolution: Active site identification and activity enhancement

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Nano Research 2021年第9期14卷 3329-3336页

作者： Shenlong Zhao Detao Zhang Shuai Jiang Yanglansen Cui Haijing Li Juncai Dong Zhirun Xie Da-Wei Wang Rose Amal Zhenhai Xia Liming Dai Australian Carbon Materials Centre(A-CMC) School of Chemical EngineeringThe University of New South WalesSydneyNSW 2052Australia Center of Advanced Science and Engineering for Carbon(Case4Carbon) Department of Macromolecular Science and EngineeringCase Western Reserve University(CWRU)10900 Euclid AvenueClevelandOH 44106USA School of Chemical and Biomolecular Engineering The University of SydneySydneyNSW 2006Australia Department of Materials Science and Engineering University of North TexasDentonTX 76203USA Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Chemical Engineering The University of New South WalesSydneyNSW 2052Australia

In this study,we developed a novel confinement-synthesis approach to layered double hydroxide nanodots(LDH-NDs)anchored on carbon nanoparticles,which formed a three-dimensional(3D)interconnected network within a porous carbon support derived from pyrolysis of metal-organic frameworks(C-MOF).The resultant LDH-NDs@C-MOF nonprecious metal catalysts were demonstrated to exhibit super-high catalytic performance for oxygen evolution reaction(OER)with excellent operation stability and low overpotential(-230 mV)at an exchange current density of 10 mA·cm^(-2).The observed overpotential for the LDH-NDs@C-MOF is much lower than that of large-sized LDH nanosheets(321 mV),pure carbonized MOF(411 mV),and even commercial RuO_(2)(281 mV).X-ray absorption measurements and density functional theory(DFT)calculations revealed partial charge transfer from Fe^(3+)through an O bridge to Ni^(2+)at the edge of LDH-NDs supported by C-MOF to produce the optimal binding energies for OER ***,coupled with a large number of exposed active sides and efficient charge and electrolyte/reactant/product transports associated with the porous 3D C-MOF support,significantly boosted the OER performance of the LDH-ND catalyst with respect to its nanosheet *** from the fact that this is the first active side identification for LDH-ND OER catalysts,this work provides a general strategy to enhance activities of nanosheet catalysts by converting them into edge-rich nanodots to be supported by 3D porous carbon architectures.

关键词： carbon nanomaterials layered double hydroxide(LDH)nanodots metal-organic framework(MOF)derivatives oxygen evolution reaction

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Development of hydroxyapatite-mediated synthesis of collagen-based copolymers for application as bio scaffolds in bone regeneration

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Journal of Fluid Mechanics 2014年第1期1621卷 53-58页

作者： Bhuiyan, Didarul Middleton, John Tannenbaum, Rina Department of Biomedical Engineering University of Alabama at Birmingham BirminghamAL35924 United States Department of Materials Science and Engineering Program in Chemical and Molecular Engineering Stony Brook University Stony BrookNY11794 United States

Hydroxyapatite (HAP) is a biocompatible bio-ceramic whose structure and composition is similar to bone. However, its lack of strength and toughness have seriously hampered its applications as a bone graft substitute material. Attempts have been made to overcome these mechanical properties deficiencies by combining HAP bioceramic material with absorbable polymers in order to improve its mechanical properties. However, poor interfacial bonding between the HAP and the polymers has limited the benefits of such biocomposite structures. At the other end of the biomaterials spectrum is collagen, which constitutes the most abundant proteins in the body and exhibits properties such as biodegradability, bioadsorbability with low antigenicity, high affinity to water, and the ability to interact with cells through integrin recognition. These favorable properties renders collagen as a natural candidate for the modification and compatibilization of the polymer-HAP biocomposite. In this study, we developed a novel approach to the synthesis of a potential bone graft material, where the HAP moiety acts not only as a bioceramic filler, but also constitutes the initiator surface that promotes the in-situ polymerization of the adsorbable polymer of choice. The synthesis of poly(D,L-lactide-co-glycolide) (PLGA) polymer was catalyzed by nano-hydroxyapatite (nHAP) particles and upon reaction completion, the biocomposite material was tethered with collagen. The synthesis was monitored by 1H NMR and FTIR spectroscopies and the products after each step were characterized by thermal analysis to probe both thermal stability, morphological integrity and mechanical properties. Copyright © Materials Research Society 2014.

关键词： Hydroxyapatite

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Amination of biochar surface from watermelon peel for toxic chromium removal enhancement

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Chinese Journal of chemical engineering 2021年第8期34卷 199-222页

作者： Mohamed A.El-Nemr Ibrahim M.A.Ismail Nabil M.Abdelmonem Ahmed El Nemr Safaa Ragab Department of Chemical Engineering Faculty of EngineeringCairo UniversityGizaEgypt Renewable Energy Program Zewail City of Science and TechnologyEgypt Environmental Division National Institute of Oceanography and FisheriesKayet BeyEl-AnfoushyAlexandriaEgypt

Watermelon peel residues were used to produce a new biochar by dehydration *** new biochar has undergone two methods of chemical modification and the effect of this chemical modification on its ability to adsorb Cr(VI)ions from aqueous solution has been *** biochars,Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA,were made from watermelon peel via dehydration with 50%sulfuric acid to give Melon-B followed by oxidation with ozone and amination using ammonium hydroxide to give Melon-BO-NH_(2) or Triethylenetetramine(TETA)to give *** prepared biochars were characterized by BET,BJH,SEM,FT-IR,TGA,DSC and EDAX *** highest removal percentage of Cr(VI)ions was 69%for Melon-B,98%for Melon-BO-NH_(2) and 99%for Melon-BO-TETA biochars of 100 mg·L^(−1) Cr(VI)ions initial concentration and 1.0 g·L^(−1) adsorbents *** unmodified biochar(Melon-B)and modified biochars(Melon-BO-NH_(2) and Melon-BO-TETA)had maximum adsorption capacities(Q_(m))of 72.46,123.46,and 333.33 mg·g^(−1),*** amination of biochar reduced the pore size of modified biochar,whereas the surface area was *** obtained data of isotherm models were tested using different error function *** Freundlich,Tempkin and Langmuir isotherm models were best fitted to the experimental data of Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA,*** adsorption rate was primarily controlled by pseudo-second–order rate ***,the functional groups interactions are important for adsorption mechanisms and expected to control the adsorption *** adsorption for the Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA could be explained for acid–base interaction and hydrogen bonding interaction.

关键词： Waste treatment Powder technology Citrullus lanatus Hexavalent chromium Biochar amination Adsorption

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