疏水化改性纳米纤维素的制备及应用研究进展

综述了疏水化改性纳米纤维素的研究进展,从表面吸附改性、对表面羟基化学改性和接枝共聚改性3个方面论述了对纳米纤维素的疏水化改性研究,介绍了疏水改性纳米纤维素及其衍生物在乳液和泡沫稳定方面以及在造纸、气凝胶和膜材料领域中的应用,并对其发展进行了展望,为其广泛应用提供了参考。     

纳米纤维素晶须表面接枝及其液晶性能研究进展

作为一种新兴的纳米生物材料,纳米纤维素日益受到各界的广泛关注,对其进行表面接枝改性并开发新的功能是十分必要的。本文综述了纳米纤维素晶须表面接枝的技术及研究进展,主要介绍了传统自由基聚合、离子和开环聚合及活性自由基聚合技术,包括氮氧自由基调控活性聚合、原子转移自由基聚合、可逆加成-断裂链转移聚合、单电子转移活性自由基聚合,讨论了各种接枝聚合方法的适用范围和优缺点。简述了点击化学在纳米纤维素晶须表面接枝的应用。通过各种聚合方法改性得到的纳米纤维素晶须接枝共聚物往往具有一些特殊的功能,某些接枝共聚物在适当的溶剂中可以形成液晶态,本文重点介绍了接枝改性的纳米纤维素晶须的液晶性能及其形成机理和影响因素等。     

纳米晶纤维素改性及其功能性材料的研究进展

纳米晶纤维素(CNC)是一种具有优异性能的纳米粒子,对CNC的改性和其功能性材料的应用一直是研究的热点。本文综述了CNC改性的方法,包括小分子改性、偶联剂改性,自由基开环接枝和ATRP接枝、RAFT接枝改性,吸附改性和一些特殊的化学改性,并分析了CNC功能性纳米材料在生物药物、聚合物电解质、生物激发力学适应性纳米材料方面的研究进展。     

利用原子转移自由基聚合法制备SiO_2/PAM纳米复合材料

为了改善二氧化硅(SiO_2)纳米粒子在聚合物基体中的分散性,采用原子转移自由基聚合(ATRP)法将聚合物接枝到纳米SiO_2表面。用甲苯-2,4-二异氰酸酯(TDI)对纳米SiO_2表面进行改性,然后与2-羟基-2′-乙基-2′-溴丙酸乙酯(HMB)反应,在表面引入ATRP引发剂,合成纳米二氧化硅颗粒(SiO_2-Br)。红外光谱(FT-IR)分析、热失重分析(TGA)和X-射线光电子能谱(XPS)结果表明,成功制备了SiO_2-Br引发剂,并通过ATRP法将聚丙烯酰胺(PAM)接枝到纳米SiO_2表面。通过凝胶渗透色谱(GPC)和分散性实验对改性后的样品进行了表征,结果表明,改性后的纳米SiO_2在甲苯中具有良好的分散性。     

纳米纤维素的疏水改性及应用研究进展

纳米纤维素作为一种性能优越的可再生纳米材料,应用前景极为广阔。然而,由于纳米纤维素结构上富含羟基,使其具有极强的亲水性,严重影响了纳米纤维素的疏水性能,并且在一定程度上限制了其在复合材料领域的应用。综述了纳米纤维素疏水改性的研究进展,从物理吸附、表面化学修饰（甲硅烷化、烷酰化、酯化等）、聚合物接枝共聚3个方面简述了目前应用较为广泛的疏水化改性方法,并对疏水纳米纤维素在包装材料、造纸、水净化等方面的应用现状进行了总结。最后对疏水改性纳米纤维素的未来发展进行了展望,旨在为疏水纳米纤维素的研究和应用提供参考。     

用于高分子材料改性领域的无机纳米填料化学改性方法

综述了对高分子材料中广泛使用的无机纳米填料进行表面化学改性的方法,包括偶联剂改性法、酯化改性法等小分子改性剂法,以及表面原位接枝聚合改性等大分子接枝法。这些方法不仅解决了无机纳米填料易团聚、分散性差及与高分子材料复合相容性不佳的问题,而且有效地提升了其在电子、催化、能源、生物医学等领域的应用性能。同时介绍了各种方法的改性机理、适用条件和优缺点,并对改性方法的工艺优化和发展研究方向进行了展望。     

纳米纤维素研究进展

综述了纳米纤维素（NCC）的性质,对物理法、化学法、生物法三种制备纳米纤维素的方法做了重点介绍。同时,对纳米纤维素在复合材料领域的应用现状进行了总结,对其在复合材料增强方面的应用进展做了较详细的介绍。最后对纳米纤维素的发展前景进行了展望。     

ATRP法接枝卤胺分子制备纤维素共聚物抗菌材料

以氯化1-烯丙基-3-甲基咪唑（[AMIM]Cl）离子液体为溶剂,采用原子转移自由基聚合法（ATRP）在微晶纤维素上接枝功能单体N-羟甲基丙烯酰胺,制备了卤胺化合物中间体,应用卤化法将接枝共聚物中的N-H转化为N-Cl键获得具有抗菌性的共聚物材料,并对其抗菌性能进行研究。通过FT-IR、¹H NMR、SEM以及抗菌测试等分析手段表征分析了聚合物的结构、表面形貌和抗菌性能等。结果表明该工艺合成了纤维素接枝N-羟甲基丙烯酰胺共聚物,接枝后表面明显变得粗糙,有利于材料与细菌的接触进而充分发挥其抗菌性能,制备的材料对金黄色葡萄球菌和大肠杆菌均表现出良好抗菌性能,在抗菌材料领域具有较好的应用前景。     

原子转移自由基聚合在纳米粒子改性方面的研究进展

介绍了原子转移自由基聚合(ATRP)在纳米粒子改性方面的研究进展,综述了基于 ATRP 的多种不同催化体系的衍生技术在纳米粒子表面改性方面的应用,其中主要包括反向原子转移自由基聚合（RATRP）和电子转移活化再生催化剂原子转移自由基聚合(AGET ATRP),并对其特点进行了概述,对纳米粒子表面引发ATRP的发展进行了展望。     

可控/活性聚合在无机粒子表面接枝研究进展

介绍了一些主要的可控／活性自由基聚合法,包括氮氧调解自由基聚合法（NMRP）、原子转移自由基聚合法（ATRP）、可逆加成断裂链转移聚合法（RAFT）在粒子表面接枝聚合形成无机纳米粒子／聚合物的壳核结构,达到了对粒子改性的目的。并提出了一些目前研究中存在的问题,对可控／活性聚合应用的发展进行了展望。     

纳米纤维素构建超疏水材料研究进展

纳米纤维素表面富含活性羟基,具有高度的亲水性和吸水性,这在很大程度上成为影响纳米纤维素在工业上大规模应用的主要因素。对纳米纤维素表面的活性羟基进行化学修饰提高其疏水性,日益成为国内外学者研究的热点。本文在简要阐述超疏水材料基本特征和制备方法的基础上,对比了不同超疏水材料制备方法（模板法、喷涂法、沉积法、刻蚀法）的优劣,重点介绍了国内外学者利用纳米纤维素构建超疏水材料（气凝胶、纸张、涂层、薄膜等）在生物医学、造纸工业、油水分离、食品包装、储能材料等不同领域的研究进展,归纳并分析了目前纳米纤维素构建超疏水材料在改性方式和性能提升等方面仍存在的问题,同时指出了纳米纤维素构建超疏水材料未来将朝着过程无污染化、工艺简化、稳定性优化等方向发展。     

Synthesis of controlled thermoresponsive PET track‐etched membranes by ATRP method

Controlled thermoresponsive PET track‐etched membranes were synthesized by grafting N‐isopropylacrylamide (NIPAAm) onto the membrane surface via atom transfer radical polymerization (ATRP). The initial measurements were made to determine the anchoring of ATRP initiator on PET membrane surface. Thereafter, polymerization was carried out to control the mass of polymer by controlling reaction time grafted from the membrane surface and, ATR‐FTIR, grafting degree measurements, water contact angle measurements, TGA, and SEM were used to characterize changes in the chemical functionality, surface and pore morphology of membranes as a result of modification. Water flux measurements were used to evaluate the thermoresponsive capacity of grafted membranes. The results show the grafted PET track‐etched membranes exhibit rapid and reversible response of permeability to environmental temperature, and its permeability could be controlled by controlling polymerization time using ATRP method. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

微孔膜法油水分离——表面性质及微观结构的研究进展

石油炼制和化工过程存在大量油水混合物体系,影响生产过程稳定性,也会造成环境污染,亟需高效低成本的油水分离技术。与气浮、离心、化学混凝等传统油水分离技术相比,微孔膜技术通过油或水的选择性渗透实现分离,具有操作简单、分离效率高、运行成本低等众多优点。然而,微孔膜处理油水混合物的分离效率和加工能力同时取决于膜材料的表面性质（表面浸润性能）和微孔结构（分离通道的尺寸效应）。本文首先基于表面润湿现象和尺寸筛分机制介绍了膜法油水分离的原理,然后从上述两个角度出发综述了近年来微孔膜法油水分离的相关研究进展,最后指出微孔膜法油水分离在迈向工业化应用的过程中还需解决的一些问题,并对未来膜材料表面性质和微孔结构的研究进行了展望。     

聚乙烯醇纤维成纤前后改性方法的研究进展

聚乙烯醇纤维具有耐酸碱、耐磨、可降解、水溶、耐腐耐候和防霉防虫等突出的优点,但存在应用范围较窄的问题。近三十年来,聚乙烯醇纤维的发展经历了服用纤维到产业用纤维的深刻转变,对聚乙烯醇纤维进行功能化改性,是提高其性能并拓宽其应用领域的有效方法。本文以聚乙烯醇纺丝成纤前后两个阶段为重点,系统介绍了纺丝液共混改性和纤维表面修饰两种典型方法。其中,共混改性分为高分子和小分子共混改性,而表面修饰按照其不同的机理则分为表面化学反应改性、表面接枝改性、物理改性等。此外,文中通过对各种改性方法优缺点的分析,阐述了共混改性和表面修饰与性能之间的关系,为选择合适的方法制备特定功能的聚乙烯醇纤维提供一定的借鉴和参考。基于现有聚乙烯醇纤维的改性方法及应用范围,提出了在深度和广度两个层次上不断加强聚乙烯醇纤维的改性研究,赋予其新的性能或满足更高要求的发展趋势。     

Functionalization of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) films via surface‐initiated atom transfer radical polymerization: Comparison with the conventional free‐radical grafting procedure

We modified hydrophobic poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBHV) films with hydrophilic chains to control their surface properties. We designed and investigated surface‐initiated atom transfer radical polymerization (SI‐ATRP) to modify the PHBHV films by grafting poly(2‐hydroxyethyl methacrylate) (PHEMA) from the surface. This method consisted of two steps. In the first step, amino functions were formed on the surface by aminolysis; this was followed by the immobilization of an atom transfer radical polymerization initiator, 2‐bromoisobutyryl bromide. In the second step, the PHEMA chains were grafted to the substrate by a polymerization process initiated by the surface‐bound initiator. The SI‐ATRP technique was expected to favor a polymerization process with a controlled manner. The experimental results demonstrate that the grafting density was controlled by the reaction conditions in the first step. The grafted films were analyzed by Fourier transform infrared spectroscopy, contact angle testing, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. The results show that grafted chains under the SI‐ATRP method were preferentially located on the surface for surface grafting and in the bulk for conventional free‐radical polymerization initiated by benzoyl peroxide. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Some water-soluble copolymers from lignin

The utilization of lignin materials would be enhanced if lignin properties could be altered through chemical modification. Towards this end, lignosulfonate, recovered from spent pulping liquors, was grafted with acrylamide or acrylic acid, using redox initiation. Study was made of the effects of some reaction variables (such as reaction medium, lignin/monomer ratio, and initiator concentration) on the copolymerization efficiency and on the copolymer characteristics. Lignosulfonate having bivalent counterions yielded better copolymerization results than that having univalent cations. Aqueous solutions of graft copolymers displayed high viscosities, and exhibited promising stability during storage and against shearing, suggesting the potential use of copolymers as water-thickening agents.     

低温等离子体与马来酸酐对UHMWPE纤维表面改性

用低温等离子体技术和接枝反应对超高分子量聚乙烯（UHMWPE）纤维进行表面处理.纤维进行低温等离子体后接枝处理的最佳工艺条件是：在80℃的1.0 mol/L的马来酸酐水溶液中加热1.5 h在维持整体形貌的前提下,在纤维长链表面引入了活性基团,增大了纤维与其他基质材料之间的化学键合能力和咬合能力,提高纤维的表面性能,从而达到表面改性的目的。     

Chemical modification of cashew gum with acrylamide using an ultrasound‐assisted method

A flocculant based on cashew gum (CG) grafted with polyacrylamide (PAM) was synthesized using potassium persulfate as the chemical initiator and ultrasound energy. The intrinsic viscosity, hydrodynamic radius, and grafting efficiency of the grafted copolymers (CG‐g‐PAM) were investigated at different monomer and initiator concentrations. The CG‐g‐PAM copolymers were evaluated in kaolin suspension and river water by using jar test procedure comparatively to a commercial flocculant (Flonex‐9045). Ultrasonication resulted in reduced reaction time and high grafting efficiency. The reaction gel point was reached within 10 min and the grafting efficiency was dependent on the acrylamide concentration. The grafted copolymer CG‐g‐PAM‐15²⁸⁵ obtained with 0.285 mmol of initiator showed higher hydrodynamic radius, with flocculation efficacy of 96% comparable with the flocculant Flonex‐9045. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43634.     

CdS/CdSe quantum dot co-sensitized graphene nanocomposites via polymer brush templated synthesis for potential photovoltaic applications

CdS/CdSe quantum dot (QDs) co-sensitized graphene sheets have been obtained via polymer brush templated synthesis. Firstly, the anionic functional polymer (polymethacrylate cadmium) was grafted via the surface initiated atomic transfer radical polymerization (ATRP) using a macromolecular initiator, which contains polymerized pyrene units for chemical anchoring on graphene surface and alkyl bromines to initiate ATRP. Then, the coordinated cadmium in the polymer chains can act as a source precursor for QDs. After reaction, polymer brushes can be recovered and act as the nanoreactor via the absorption of cadmium ions by carboxylate groups. So, high density QDs can be multiply uploaded onto the graphene surface by repeated steps. The as-prepared composite materials exhibited significantly enhanced visible light response compared to plain graphene, and have potential applications as the platform to build solar cell assembles.     

碳限域铁基费托合成催化剂研究进展

利用费托合成工艺,将煤、生物质等原料气化产生的合成气转化为液体燃料或化学品,符合我国能源特点和战略需求,而高性能铁基费托合成催化剂的开发能够推动该工艺进步,载体的结构和电子环境会显著影响催化剂的性质。碳材料是铁基费托合成催化剂备受关注的一类载体。本文回顾了不同种类的碳限域载体（包括碳纳米管、介孔碳、有机物衍生、石墨烯等）在费托合成中的最新进展,并重点从几何效应和电子效应两方面阐述了碳材料对铁基费托合成催化剂的限域作用,如对气体扩散和局部浓度、铁物种还原和碳化、碳化铁的相态和晶粒尺寸的稳定性等方面的影响。今后的研究重点是解决催化剂可控制备及碳材料本身在工业操作条件下的稳定性问题,并进一步探明碳包覆结构对碳化铁物相形成和反应机理的影响机制。