A phase-field model for simulating various spherulite morphologies of semi-crystalline polymers

A modified phase-field model is proposed for simulating the isothermal crystallization of polymer melts. The model consists of a second-order phase-field equation and a heat conduction equation. It obtains its model parameters from the real material parameters and is easy to use with tolerable computational cost. Due to the use of a new free energy functional form, the model can reproduce various single crystal morphologies of polymer melts under quiescent conditions, including dendritic, lamellar branching, ring-banded, breakup of ring-banded, faceted hexagonal, and spherulitic structures. Simulation results of isotactic polystyrene crystals demonstrate that the present phase-field model has the ability to give qualitative predictions of polymer crystallization under isothermal and quiescent conditions.

Low-Enthalpy and High-Entropy Polymer Electrolytes for Li-Metal Battery

lonic-conductive solid-state polymer electrolytes are promising for the development of advanced lithium batteries yet a deeper understanding of their underlying ion-transfer mechanism is needed to improve performance.Here we demonstrate the low-enthalpy and high-entropy(LEHE)electrolytes can intrinsically generate remarkably free ions and high mobility,enabling them to efficiently drive lithium-ion storage.The LEHE electrolytes are constructed on the basis of introducing CsPbl_(3)perovskite quantum dots(PQDs)to strengthen PEO@LiTFSI complexes.An extremely stable cycling>1000 h at 0.3 mA cm^(-2)can be delivered by LEHE electrolytes.Also,the as-developed Li|LEHE|LiFePO_(4)cell retains 92.3%of the initial capacity(160.7 mAh g^(-1))after 200 cycles.This cycling stability is ascribed to the suppressed charge concentration gradient leading to free lithium dendrites.It is realized by a dramatic increment in lithium-ion transference number(0.57 vs 0.19)and a significant decline in ion-transfer activation energy(0.14 eV vs 0.22 eV)for LEHE electrolytes comparing with PEO@LiTFSI counterpart.The CsPbl_(3)PQDs promote highly structural disorder by inhibiting crystallization and hence endow polymer electrolytes with low melting enthalpy and high structural entropy,which in turn facilitate long-term cycling stability and excellent rate-capability of lithium-metal batteries.

Interpenetrating network-reinforced gel polymer electrolyte for ultra-stable lithium−iodine batteries

Li-I_(2) batteries have attracted much interest due to their high capacity,exceptional rate performance,and low cost.Even so,the problems of unstable Li anode/electrolyte interface and severe polyiodide shuttle in Li-I_(2) batteries need to be tackled.Herein,the interfacial reactions on the Li anode and I_(2) cathode have been effectively optimized by employing a well-designed gel polymer electrolyte strengthened by cross-linked Ti-O/Si-O(GPETS).The interpenetrating network-reinforced GPETS with high ionic conductivity(1.88×10^(-3)S cm^(-1)at 25℃)and high mechanical strength endows uniform Li deposition/stripping over 1800 h(at 1.0mA cm^(-2),with a plating capacity of 3.0mAh cm^(-2)).Moreover,the GPETS abundant in surface hydroxyls is capable of capturing soluble polyiodides at the interface and accelerating their conversion kinetics,thus synergistically mitigating the shuttle effect.Benefiting from these properties,the use of GPETS results in a high capacity of 207 mAh g^(-1)(1 C)and an ultra-low fading rate of 0.013%per cycle over 2000 cycles(5 C).The current study provides new insights into advanced electrolytes for Li-I_(2) batteries.

A Modified Phase-Field Model for Polymer Crystal Growth

The irrationality of existing phase field model is analyzed and a modified phase-field model is proposed for polymer crystal growth, in which the parameters are obtained from real materials and very simple to use, and most importantly, no paradoxical parameters appeared in the model. Moreover, it can simulate different microstructure patterns owing to the use of a new different free energy function for the simulation of morphologies of polymer. The new free energy function considers both the cases of T〈Tm and T≥Tm, which is more reasonable than that in published literatures that all ignored the T≥Tm case. In order to show the validity of the modified model, the finite difference method is used to solve the model and different crystallization morphologies during the solidification process of isotactic polystyrene are obtained under different conditions. Numerical results show that the growth rate of the initial secondary arms is obviously increased as the anisotropy strength increases. But the anisotropy strength seems to have no apparent effect on the global growth rate. The whole growth process of the dendrite depends mainly upon the latent heat and the latent heat has a direct effect on the tip radius and tip velocity of side branches.

A novel permselective organo-polysulfides/PVDF gel polymer electrolyte enables stable lithium anode for lithium–sulfur batteries

Lithium-sulfur(Li-S)battery can satisfy the need of the future power battery market because of its high energy density,but the hidden dangers caused by lithium anode have seriously hindered their commercialization.Herein,an innovative gel polymer electrolyte(GPE)composed of polyvinylidene fluoride(PVDF)and organo-polysulfide polymer(PSPEG)is proposed,which could be used in semisolid-state Li-S batteries for protection of Li anodes.Particularly,organo-polysulfide polymer could chemically/electrochemically generate both inorganic and organic components simultaneously in-situ once contacting fresh Li metal surface and/or during discharging processes.And these inorganic/organic components could participate in the formation of the SEI layer and finally constitute a stable and flexible hybrid SEI layer on the surface of Li metal anode.Moreover,the organic components were permselective to lithium ions against anions.Therefore,PVDF/PSPEG GPE ensures the ideal chemical and electrochemical properties for Li-S batteries.Our work demonstrates an effective solution to solve the problems about Li anodes and contributes to the development of the safe Li metal batteries.

Supramolecular dendritic polymers for diagnostic and theranostic applications

Supramolecular dendritic polymers（SDPs）provide a new opportunity for the precision diagnosis and treatment of diseases. SDPs are a novel class of non-covalently bonded macromolecules with highly branched structure and three-dimensional globular topology, which exhibit dynamic/reversible features and unique physical/chemical properties（e.g., high solubility, low viscosity, and numerous functional terminal groups）. The reversibility of non-covalent interactions endows SDPs with the ability of facile preparation, smart responsiveness, and simple metabolism. These special characteristics determine the properties of SDPs, which are the key points for theranostic applications, including diagnosis,therapy, and theranostics. In this review, we briefly summarize the design and synthesis of SDPs with aimed structures,properties, functions as well as their present diagnostic and theranostic applications. These developments on the preparation and applications of SDPs for diagnostic and theranostic purpose promote interdisciplinary research fields of chemistry, material and biomedical science.

A lithiated gel polymer electrolyte with superior interfacial performance for safe and long-life lithium metal battery

Rechargeable lithium metal batteries(LMBs)have gained much attention recently.However,the short lifespan and safety issues restrict their commercial applications.Here we report a novel gel polymer electrolyte(GPE)based on lithiated poly(vinyl chloride-r-acrylic acid)(PVCAALi)to realize dendritesuppressing and long-term stable lithium metal cycling.PVC chains ensure the quick gelation process and high electrolyte uptake,and lithiated PAA segments enable the increase of mechanical strength,acceleration of lithium-ion transmission and improvement of interfacial compatibility.PVCAALi GPE showed much higher mechanical strength compared with other free-standing GPEs in previous works.It displays a superior ionic conductivity of 1.50 m S cm^(-1) and a high lithium-ion transference number of 0.59 at room temperature.Besides,the lithiated GPE exhibits excellent interfacial compatibility with lithium metal anodes.Lithium symmetrical cells with PVCAALi GPE yield low hysteresis of 50 m V over1000 h at 1.0 m A cm^(-2).And the possible mechanism of the lithiated GPE with improved lithium-ion transfer and interfacial property was discussed.Accordingly,both the Li4Ti5O12/Li and lithium-sulfur(Li-S)cells assembled with PVCAALi GPE show outstanding electrochemical performance,retaining high discharge capacities of 133.8 m Ah g^(-1) and 603.8 m Ah g^(-1) over 200 cycles,respectively.This work proves excellent application potential of the highly effective and low-cost PVCAALi GPE in safe and long-life LMBs.

树枝状聚合物对聚乳酸熔体微分电纺纤维膜的增韧改性研究

采用树枝状聚合物CYD-T151为增塑剂,通过熔融共混方式对聚乳酸(PLA)进行改性,探究了CYD-T151含量、纺丝温度和纺丝电压对熔体微分电纺PLA及PLA/CYD-T151纤维平均直径、直径分布和纤维膜拉伸力学性能的影响。结果表明,树枝状聚合物CYD-T151的加入可有效提高PLA的熔体流动性,降低纤维细度,当CYD-T151含量(质量分数,下同)为1.25%、纺丝温度为240℃、纺丝电压为55 kV时,熔体电纺纤维的纤维平均直径为1.360μm,较纯PLA减小了49.72%;树枝状聚合物CYD-T151作为增塑剂,可有效提高PLA熔体电纺纤维膜的韧性,当CYD-T151含量为1.25%,纺丝温度为240℃,纺丝电压为55 kV时,PLA/CYD-T151纤维膜的抗拉强度和断裂伸长率分别为11.50 MPa和92.33%,较纯PLA提高了4.07%和13.99%。

以聚丙烯酰胺为电解液添加剂稳定金属锌负极

水系锌离子电池因具有成本低廉和安全性高等优点而被认为是极具前景的储能体系。金属锌因具备高的理论体积比容量和较低的氧化还原电位,可以直接用作水系锌离子电池负极,但金属锌负极存在自腐蚀和锌枝晶生长等问题,导致电池循环寿命缩短,严重制约了其实际应用。本工作设计了一种聚丙烯酰胺(PAM)聚合物作为锌离子电池的电解液添加剂,结果显示在2 g/L PAM添加剂电解液体系中电池表现出最优的循环性能,在5 mA/cm^(2)、1 mAh/cm^(2)时锌-锌对称电池能稳定循环2800 h,进一步的电化学测试和扫描电子显微镜表征证明PAM添加剂能够很好地抑制金属锌枝晶和减轻锌电极腐蚀。该工作为通过功能性电解质添加剂设计高性能的水系电解液添加剂提供了一种新思路。

Luminescent Metallo-Supramolecular Polymers

Luminescent metallo-supramolecular polymers are a type of functional supramolecular architectures which integrates the advantages of emission,metal-coordination,supramolecular chemistry as well as polymeric properties to realize advanced functions.Due to the abundant stimuli-responsiveness of supramolecular assemblies and the light-emitting properties,they have been widely applied as chemo-sensors,light-emitting devices,contrast agents for bio-imaging,etc.In this review,we classify luminescent metallo-supramolecular polymers based on the types of species (lanthanides,organometallic compounds,oligomer or polymer-based ligands,small-molecule-based organic ligands) used to generate the luminescence and summarize recent developments of luminescent metallo-supramolecular polymers.We mainly focus on the functions and applications of luminescent metallo-supramolecular polymers and hope to give our reader a snapshot of research on luminescent metallo-supramolecular polymers and encourage more scientists to devote into this promising area.

Quantification and visualization of spatial distribution of dendrites in solid polymer electrolytes

Integrating lithium metal anodes with polymer electrolytes is a promising technology for the next generation high-energy-density rechargeable batteries.As the progress is often hindered by the dendrite growth upon cycling,quantifying three-dimensional(3D)microstructures of dendrites in polymer electrolytes is essential to better understanding of dendrite formation for the development of mitigation strategies.Techniques for 3D quantification and visualization of dendrites,especially those with low Li contents,are rather limited.This study reports quantitative measurements of the spatial distribution of Li dendrites grown in solid polymer electrolytes using 3D tomographic neutron depth profiling(NDP)with improved spatial resolution,compositional range,and data presentation.Data reveal heterogeneous distribution of Li over length scales from tens nanometers to centimeters.While most dendrites grow from the plating toward the stripping electrode with dwindling Li quantities,dendrites apparently grown from the Li-stripping electrode are also observed.The discovery is only possibly due to the unique combination of the high specificity and high sensitivity of the neutron activation analysis of Li isotope.

Enzyme/pH-sensitive dendritic polymer-DOX conjugate for cancer treatment

It is in a great demand to design a biodegradable, tumor microenvironment-sensitive drug delivery system to achieve safe and highly efficacious treatment of cancer.Herein, a novel pH/enzyme sensitive dendritic pdi HPMADOX conjugate was designed. di HPMA dendritic copolymer with GFLG segments in the branches which are sensitive to the intracellular enzyme of the tumor was prepared through RAFT polymerization. DOX was attached to dendritic di HPMA polymer through a pH-sensitive hydrazone bond. The dendritic pdi HPMA-DOX conjugate self-assembled into nanoparticles with an ideal spherical shape at a mean size of 103 nm. The DOX attached to the polymeric carrier was released in an acidic environment, and the GFLG linker for synthesizing the dendritic vehicle with a high molecular weight（M_W, 220 kDa） was cleaved to release low MWsegments（〈40 kDa） in the presence of cathepsin B. The dendritic polymeric conjugate was internalized via an endocytic pathway, and then released the anticancer drug, which led to significant cytotoxicity for tumors. The blood circulation time was profoundly prolonged, resulting in high accumulation of DOX into tumors. In vivo anti-tumor experiments with 4 T1 tumor bearing mice demonstrated that the conjugate had a better antitumor efficacy in comparison with free DOX. Additionally, body weight measurements and histological examinations indicated that the conjugate showed low toxicities to normal tissues. This dendritic polymeric drug carrier in a response to intracellular enzyme and acidic pH of tumor tissue or cells holds great promise in tumor-targeted therapy.

A hybrid lithium sulfonated polyoxadiazole derived single-ion conducting gel polymer electrolyte enabled effective suppression of dendritic lithium growth

Lithium metal is deemed as an ideal anode material in lithium-ion batteries because of its ultrahigh theoretical specific capacity and the lowest redox potential.However,the rapid capacity attenuation and inferior security resulting from the dendritic lithium growth severely limit its commercialization.Herein a novel hybrid gel polymer electrolyte (GPE) based on electrospun lithium sulfonated polyoxadiazole (LiSPOD) nanofibrous membrane swelled by lithium bis(trifluoromethanesulfonyl)imide (Li TFSI) ether liquid electrolyte is proposed to address the issue of lithium dendrites.The Li-SPOD membrane synthesized by a simple one-pot method exhibits excellent mechanical strength and thermal resistance due to its high molecular weight and rigid backbone.The electron-withdrawing oxadiazole ring and oxadiazole ring-Li;complex,and N,O heteroatoms with lone pairs of electrons in Li-SPOD macromolecular chains facilitate the dissociation of-SO_(3)Li group and Li^(+)transference.The hybrid Li-SPOD GPE exhibits both a high lithium-ion transference number (0.64) and high ionic conductivity (2.03 m S/cm) as well as superior interfacial compacity with lithium anodes.The Li Fe PO_(4)-Li cell using this novel GPE can operate steadily at 2C for 300 cycles,remaining a high discharge capacity of 125 m Ah/g and dendrite-free anode.Remarkable performance improvements for the Li-Li and Cu-Li cells are also presented.

Synthesis of Helical Poly(phenylacetylene)s Carrying Dendritic Pendants with Varied Branching Densities Through Polymerization in Different Solvents

Helical poly(phenylacetylene)s(PPAs)have received extensive attention because of their features in dynamic chirality and promising applications.Therefore,understanding relationship among the polymer molecular structures,polymerization conditions and tunability of their chirality is of key scientific value.Recently,we developed a novel class of dendronized PPAs carrying 3-fold dendritic oligo(ethylene glycols)(OEGs)via alanine linkage,and found that these bulky polymers exhibited tunable helical conformations through thermally-mediated dehydration and aggregation.Herein,we report on synthesis of a homologous series of dendronized PPAs that carry 2-fold,3-fold or 6-fold dendritic OEG pendants,and focus on effects of molecular topological structures,peripheral units and polymerization solvents on the thermoresponsiveness and their conformation switching behaviors.Effects of branching density and peripheral units(ethoxyl or methoxyl)of the dendritic OEG pendants were examined,and found to play a decisive role on the helical conformation and thermoresponsiveness of these dendronized PPAs due to their different bulkiness and overall hydrophilicity.In addition,different polymerization solvents were checked for their possible influence on the polymerization,thermoresponsive behavior and the chirality of the resulting polymers.For polymerization in selective solvents like water or methanol,the obtained dendronized PPAs exhibited weak thermal transitions,while polymerization in non-selective solvent like THF furnished PPAs with characteristic thermoresponsive behavior,indicating that solvents were involved in the process of polymerization of the dendronized macromonomers.More interestingly,different chiralities of the PPAs through polymerization in various solvents were retained,irrelevant to the purification process and solvents treatments.This work suggests that the topological structures together with polymerization solvents can modulate the thermoresponsive behavior and helical conformation of the dendronized PPAs.

高分子表面活性剂的研究现状

综述了高分子表面活性剂的研究现状，重点介绍了高分子表面活性剂的分类，性质及其制备方法。

聚酰胺-胺型树枝状化合物与细胞色素C的结合作用

The methyl ester terminated G1 5,2 5 and 3 5 poly(amidoamine) dendrimers (PAMAM) are hydrolyzed by using NaOH to obtain external carboxylate groups with them (PAMAMC).These dendrimers show interaction with cytochrome C in some extent.For example,the reduction rate of Fe Ⅲ cytochrome C to Fe Ⅱ cytochrome C by ascorbic acid was clearly slowed down because of the interaction between cytochrome C and PAMAM dendrimers.The reaction happened only betweem Fe Ⅲ cytochrome C and ascorbic acid,it showed a pseudo first order constant of 3 48 min -1 .When PAMAMC (G2 5 or 3 5) dendrimers were added in the reaction system,the pseudo first order constant dropped to 1 40 or 1 32 ?min -1 .The association constant of 1:1 cytochrome C G2 5C is 2 4×10 4 and the association constant of 1:1 cytochrome C G3.5C is 2 6×10 4.

金刚烷的应用开发

综述了近年来金刚烷化学领域的研究进展 ,讨论了其在合成及改性高聚物方面的应用。

超支化聚合物研究进展

超支化聚合物由于具有高度文化三维球状结构以及众多的端基，因此显示出与相应线型分子截然不同的性质，如低粘度、无链缠结和良好的溶解性．本文讨论了超支化聚合物的特性与表征，对合成超支化聚合物所用单体以及产物作了详细介绍，旨在引起对该领域的兴趣．

树枝状聚醚酰胺基紫外固化粉末涂料的研究

论述了紫外固化粉末涂料的优点、加工工艺、应用领域以及国际上研究与开发动态。着重介绍了本实验室合成的光固半结晶树枝状聚醚酰胺的结晶性能。

高支化聚合物的研究进展及应用前景

综述了近几年国内外高支化聚合物的研究进展及其应用前景。