种子聚合法制备非球形聚合物颗粒的研究进展

十年前,光子晶体的需求促进了非球形颗粒的研究热潮。非球形颗粒由于其对称性下降,带来了新的性能和应用前景,成为当前材料领域研究的热点,得到了较广泛研究,目前其制备方法包括种子聚合法、自组装法、粒子聚集法、微流体法和机械拉伸法等。本文简述了种子聚合法的发展历程,介绍了种子聚合法制备非球形聚合物颗粒的相关机理,以种子微球材质分类综述了种子聚合法制备非球形聚合物颗粒的形貌和结构控制技术进展,概述了其潜在的应用领域,展望了可能的发展趋势。     

基于微流控技术制备微/纳米粒子材料

具有特殊性质的微/纳米粒子,在药物传递、吸收分离、光电材料和磁性设备等多个领域具有重要的应用价值。近年来,微流控技术在有机合成、高分子化学以及材料制备等领域表现出传统釜式反应器无法比拟的优势。本文介绍了基于微流控技术制备微/纳米粒子的最新研究进展,包括以单乳液为模板合成球形和非球形聚合物粒子、无机物粒子、贵金属纳米粒子和半导体纳米粒子,以多重乳状液为模板制备壳核粒子、Janus粒子和微囊。     

晶种法合成金溶胶过程中非球形粒子的抑制

羟胺晶种法制备金纳米粒子时会观察到少量的非球形粒子副产物.研究发现,反应试剂的比例以及试剂的加样顺序对非球形粒子的产生具有明显的影响.羟胺与金氯酸的摩尔比例([NH2OH]:[HAuCl4])较高时能够抑制非球形粒子的生成,较低时则生成较多的非球形粒子.不同的加样顺序使得加样过程中[NH2OH]:[HAuCl4]不同,也可以导致产物中非球形粒子含量的差异.基于以上发现,采用较大的NH2OH用量以维持反应过程中的[NH2OH]:[HAuCl4]比例在10～30左右,并采用适当的加样顺序(先将晶种同NH2OH混合,再加HAuCl4),从14 nm的晶种出发以逐步(step-by-step)的方式依次合成了平均粒径为26、57、81和130 nm的金纳米粒子,产物中基本不含非球形粒子,粒径可控，并具有良好的单分散性(RSD为～10％).     

聚合物负载金属纳米粒子型核壳结构催化剂的研究

核壳结构聚合物负载型催化剂因其载体材料独特的结构、形貌和性质而具有优异的催化活性,成为了催化化学领域研究的热点。本文综述了聚合物负载金属纳米粒子型核壳结构催化剂,包括球形聚合物刷负载金属纳米粒子、聚合物中空微球负载金属纳米粒子、聚合物实心微球表面包覆金属纳米粒子等类型催化剂的制备及其相应的催化性能,强调了各类载体的组成和结构特点对催化活性及其稳定性的影响。最后总结了该类催化材料的优势和不足,并对其性能和应用进行了展望。     

一步溶剂热法合成C掺杂介孔TiO_2可见光光催化材料

在无模板剂的条件下,以钛酸四丁酯为钛源,采用一步溶剂热法,在乙醇体系中合成出C掺杂TiO2球状介孔可见光光催化材料.通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、氮气吸附-脱附仪、X射线光电子能谱(XPS)、固体漫反射(UV-Vis)以及光降解罗丹明B实验等对其进行了结构表征和性能测试.实验结果表明,合成样品为锐钛矿晶型,材料表现为由纳米粒子堆积而成的大小均一的球形形貌.TiO2材料的结晶度和粒子形貌大小可以通过乙酸加入量来进行调控,这对于实际应用具有重要意义.同时,通过测试证明样品中的C原子进入TiO2晶格内部,取代了O原子的位置,窄化了TiO2内部的能带结构,从而大大提高了材料的可见光光催化活性,结果证明合成材料对污染物具有很好的吸附性能和光降解性能.     

金属有机框架复合材料的合成及其在肿瘤诊疗领域中的应用

金属-有机框架(MOF)材料是指以有机配体为连接体和以金属离子簇为节点,通过配位键组装形成的具有周期性结构的配位化合物。该材料在气相传导、光学催化以及生物应用领域都有着应用潜力。不同形貌、大小和组分的MOF材料具有不同的物理化学性质。将金属纳米粒子和MOF材料的性能相结合,就能够有效地避免金属纳米粒子和MOF材料的相互凝聚。本文主要阐述了MOF材料的几种合成方法,包括气相法、液相法、固相法、模板法、微波法和电化学法,并对其优缺点进行了讨论。重点分析了其在肿瘤领域中的应用,包括药物负载、荧光标记和光动力学疗法等。最后指出今后其主要的研究方向是改善生物相容性、降低制备成本、扩展生物MOF及其负载药物的种类,使其应用到更多疾病的治疗上。     

模板法合成纳米结构材料

模板法（包括硬模板和软模板法）是制备纳米结构材料的常用方法,可用来制备多种物质的各种形状（如：球形粒子、一维纳米棒、纳米线、纳米管以及二维有序阵列等）的纳米结构,近年来关于这一领域的研究较为活跃。本文介绍了近年来利用氧化铝、二氧化硅、碳纳米管、表面活性剂、聚合物、生物分子等作模板制备多种物质的纳米结构材料的一些进展。     

胶体晶体微球及其生物医学应用

光子晶体(PhCs)是由单分散纳米粒子周期性排列形成的材料,具有光子禁带,频率落在光子禁带内的光被禁止传播,这个特性激起了研究者对其制备和应用的研究热情。然而,一般的光子晶体材料都具有角度有偏性质,限制了其在宽视角光学材料和设备上的应用。近几年有一系列围绕球形胶体光子晶体材料的研究成果问世,由于球形的对称性,球形胶体晶体的衍射峰不会随着光的入射角变化而发生变化,从而拓宽了胶体晶体的应用范围。随着微流控技术被用于制备液滴模板,球形胶体晶体的制备取得了巨大的进步。微流控技术不仅保证了液滴模板的单分散性,还增加了胶体晶体微球的结构与功能的多样性。胶体晶体微球这些特有的性质,可以很好地将光子晶体材料与编码、非标记检测、细胞培养以及载药等生物医学领域连接起来,为其应用提供了广阔的前景。本文总结了球形光子晶体的研究进展,包括球形光子晶体的设计、制备及其生物医学应用,最后,对球形光子晶体未来的发展方向作了展望。     

氧化石墨烯分离膜机械性能调控

氧化石墨烯(Graphene oxide, GO)片层组装制备的分离膜,具有可调控的纳米通道和独特的分离性能,是一种很有前景的分离材料,但较差的机械性能制约了其实际应用。将活性分子、阳离子等粒子引入到GO膜的片层间,利用其与GO形成的稳定键合可提高GO膜的机械性能。本文综述了国内外在GO膜机械性能调控方面的研究进展。依据引入的粒子与GO成键的类型可分为共价键法和非共价键法,其中共价键法又分为大分子共价键法和小分子共价键法,非共价键法分为氢键法、π-π键法和离子键法。无论共价键法还是非共价键法都能显著提升GO膜的机械性能,其中共价键法对GO复合膜的增强效果优于非共价键法,大分子共价键法优于小分子共价键法。最后,阐述了现有方法存在的问题,并对未来的发展前景做出了展望。     

高分子微凝胶控制合成无机-有机复合材料研究进展

高分子微凝胶是一类具有三维网络结构的分子内交联的高分子球形微粒,其物理、化学性质与其构象变化有着密切的关系,对于外界环境条件如温度、pH、离子强度、电场或磁场等的改变,微凝胶即表现出相应的体积相转变特性.近年来,基于高分子微凝胶对外界的刺激相应性与无机纳米粒子的特殊性能制备得到了各种有机-无机复合材料.本文根据微凝胶在无机微、纳米材料制备过程中所起的作用,将基于高分子微凝胶制备无机-有机复合微、纳米材料的方法分为原位合成法、物理诱捕法和聚合法,并分别从各类方法的特点和应用等方面进行详尽地分析和阐述.     

天然-合成高分子生物杂化材料在生物医学领域中的应用

综述了天然—合成高分子生物杂化材料在生物医学领域中的应用，并分析了它作为组织工程基质和药物载体的优点，指出生物杂化材料是生物医用材料的发展趋势。     

Lattice Boltzmann simulation of particles agglomeration and rheology in a particulate flow

The dynamics and rheology of particles in a Newtonian fluid subjected to shear are simulated using Lattice Boltzmann Method. A computationally-efficient Smoothed Profile Method is used to resolve fluid-solid interactions, and the Lennard-Jones inter-particle potential is implemented to account for inter-particle forces. The use of a bi-periodic computational domain with Lees-Edward boundary conditions allows simulation for systems consisting of a large number of particles under shear. The method is validated for single and dual particle problems and an analysis is performed for multi-particle problems under a range of shear rates and particle fractions. The introduction of particle-particle interactions, which are physically important in many engineering processes, is found to have a considerable impact on the dynamics, agglomeration and rheology. The total stress exhibits high unsteadiness primarily due to the solid component contribution, at higher particle fractions. The simulations underscore the complex interplay between shear, interparticle forces and agglomeration and the complex dependencies of the rheological properties.     

Metal particle adsorption and diffusion in a model polymer/metal composite system

We have developed a model polymer/metal composite system based on the adsorption of colloidal gold particles from a dilute aqueous suspension to the surface of poly(2-vinylpyr-idine) (PVP). Particle coverages and tracer diffusion coefficients for the particles within a PVP matrix phase were measured by Rutherford backscattering spectrometry. The adsorption process is quantitatively described by a diffusion-limited mechanism where gold particles irreversibly adsorb to the surface of the polymer film. Model dispersions produced in this way are excellent model systems for studying the fundamental properties of metal particle dispersions, since the particle size and the areal density of particles on the surface are well-controlled. Diffusion coefficients for the gold particles within PVP were also measured. The diffusion of the gold particles was found to be coupled to the bulk viscosity of the polymer, even though the size of the gold particles was only slightly larger than the mesh size of the entanglement network for PVP. © 1995 John Wiley & Sons, Inc.     

Synthesis and characterization of dual‐responsive micrometer‐sized core‐shell composite polymer particles

Dual‐responsive micrometer‐sized core‐shell composite polymer particles were prepared by dispersion polymerization followed by seeded copolymerization. Polystyrene (PS) particles prepared by dispersion polymerization were used as core particles. N‐isopropyl acrylamide (NIPAM) and methacrylic acid (MAA) were used to induce dual‐responsive that is thermo‐ and pH‐responsive properties in the shell layer of composite polymer particles, prepared by seeded copolymerization with PS core particles. Temperature‐ and pH‐dependent adsorption behaviors of some macromolecules on composite polymer particles indicate that produced composite polymer particles exhibit dual‐responsive surface properties. Copyright © 2007 John Wiley & Sons, Ltd.     

Sequence-defined Pareto frontier of a copolymer structure

The correlations between the sequence of monomers in a macromolecule and its three-dimensional (3D) structure is a grand challenge in polymer science. The properties and functions of macromolecules depend on their 3D shape that has appeared to be dictated by their monomer sequence. However, the progress towards understanding the sequence–structure-property correlations and their utilization in materials engineering are slow because it is almost impossible to characterize an astronomically large number of possible sequences of a copolymer using traditional experimental and simulation methods. To address this problem, here, we combine evolutionary computing and coarse-grained molecular dynamics (CGMD) simulation and study the sequence-structure correlations of a model AB-type copolymer in a solution and assess the impact of sequence on the packing density in its bulk phase. The CGMD-based evolutionary algorithm (EA) screens the sequence space of a single chain copolymer efficiently and identifies a wide range of single-molecule structures including extremal radii of gyration. The data are utilized to estimate the Pareto front of the structure-space of a binary copolymer as a function of its composition. The monomer packings in single-molecule solution phase and multimolecular bulk phase are found to be identical. The work highlights the opportunities of sequence-specific control of macromolecular structure for designing target materials.     

Multifunctional micro-/nanoscaled structures based on polyaniline: an overview of modern emerging devices

With the advent of Materials Science-based technological advances, the fabrication of materials that could simultaneously exhibit both mechanical and processing properties of polymers and unique electrical characteristics of metals is a requirement with prior mandate. With the development of conducting polymers, great opportunities have been established, and novel devices with the significant features have emerged. Polyaniline (PANI) and its derivatives have attracted immense attention because of their fascinating properties, including high conductivity, inexpensiveness of starting material, unique redox behavior, facile synthesis, tunable properties, appropriate electrochemical and environmental stability, and strong bimolecular interactions. Nanostructures based on PANI have shown improved functionalities in various applications. In this article, different synthesis strategies such as interfacial polymerization, microwave-assisted polymerization, and sonochemical polymerization among others have been summarized. Besides, PANI-based nanocomposites and their various industrial, as well as biomedical applications in supercapacitors, batteries, gas vapor sensors, printable electronics, electrochromics, actuators, electrostatic dissipation, electromagnetic interference shielding, corrosion protection, filtration membranes, microbial fuel cell, biosensors, tissue engineering, and drug delivery systems, have been discussed in detail.     

Polythiolactone-Decorated Silica Particles: A Versatile Approach for Surface Functionalization,Catalysis and Encapsulation

The surface chemistry of colloidal silica has tremendous effects on its properties and applications. Commonly the design of silica particles is based on their de novo synthesis followed by surface functionalization leading to tailormade properties for a specific purpose. Here, the design of robust “precursor” polymer-decorated silica nano- and microparticles is demonstrated, which allows for easy post-modification by polymer embedded thiolactone chemistry. To obtain this organic-inorganic hybrid material, silica particles (SiO₂P) were functionalized via surface-initiated atom transfer radical polymerization (SI-ATRP) with poly(2-hydroxyethyl acrylate) (PHEA)-poly(thiolactone acrylamide (PThlAm) co-polymer brushes. Exploiting the versatility of thiolactone post-modification, a system was developed that could be used in three exemplary applications: 1) the straightforward molecular post-functionalization to tune the surface polarity, and therefore the dispersibility in various solvents; 2) the immobilization of metal nanoparticles into the polymer brushes via the in situ formation of free thiols that preserved catalytic activity in a model reaction; 3) the formation of redox-responsive, permeable polymer capsules by crosslinking the thiolactone moieties with cystamine dihydrochloride (CDH) followed by dissolution of the silica core.     

聚醚砜/热致液晶高分子原位复合材料的结构与性能

<正> 国际上关于热致液晶高分子(TLCP)原位复合材料的报道始于80年代,原位复合增强材料的增强形式不是在树脂加工前实际存在的,而是在加工过程中形成的,原位复合的方法是将TLCP掺入树脂基体,使其在特定的流场和应力场作用下,诱导取向并形成徽     

通过分子复合超分子方法制备高性能高分子材料

分子复合可调控聚合物超分子结构和聚集态结构,提高其性能,是高分子材料制备和高性能化的超分子方法.本文介绍了我们研究组近几年来通过分子复合超分子方法制备新型高分子材料的一些研究工作,如实现PVA的热塑加工,制备高性能熔纺纤维、吹塑薄膜、中空瓶、注塑制品等;制备新型聚合物无卤阻燃剂MCA,大大简化其合成工艺,并具有更高阻燃...     

Influence of poly(ethylene oxide) brushes on the rheological properties of MgO colloidal suspensions in water

A combined experimental and multiscale simulation study of the influence of polymer brush modification on interactions of colloidal particles and rheological properties of dense colloidal suspensions has been conducted. Our colloidal suspension is comprised of polydisperse MgO colloidal particles modified with poly(ethylene oxide) (PEO) brushes in water. The shear stress as a function of shear rate was determined experimentally and from multiscale simulations for a suspension of 0.48 volume fraction colloids at room temperature for both bare and PEO-modified MgO colloids. Bare MgO particles exhibited strong shear thinning behavior and a yield stress on the order of several Pascals in both experiments and simulations. In contrast, simulations of PEO-modified colloids revealed no significant yielding or shear thinning and viscosity only a few times larger than solvent viscosity. This behavior is inconsistent with results obtained from experiments where modification of colloids with PEO brushes formed by adsorption of PEO-based comb-branched chains resulted in relatively little change in suspension rheology compared to bare colloids over the range of concentration of comb-branch additives investigated. We attribute this discrepancy in rheological properties between simulation and experiment for PEO-modified colloidal suspensions to heterogeneous adsorption of the comb-branch polymers.