新型室温酯化法接枝聚合物改性SiO_2纳米微粒

提出了一种在室温、大气环境等温和条件下通过酯化反应将端羧基聚合物链接枝到纳米SiO2微球表面从而制备有机/无机复合纳米微粒的新方法.该方法通过以下两个步骤得以实现,即第一,用3-环氧丙基三甲氧基硅烷对纳米SiO2微球表面进行改性处理,接着将引入到纳米SiO2表面的环氧基团转化为烷羟基基团;第二,通过引入到纳米SiO2微球表面的烷羟基与聚合物中的端羧基在室温下发生酯化反应,从而将聚合物接枝到纳米SiO2表面制得复合微球.利用XPS、FTIR、TEM和TGA等测试手段对纳米SiO2的改性过程以及聚合物接枝后得到的复合微球进行了表征.研究结果表明,该室温酯化接枝方法具有较高的接枝率,接枝到无机纳米微粒表面的聚合物占复合微球质量的55wt%～70wt%;接枝聚合物后,纳米SiO2微球的粒径从40nm增加到64～75nm,从而得到了以SiO2为核、以聚合物为壳的有机-无机复合微球.     

SiO2交联剂交联MMA聚合制备PMMA/SiO2纳米复合材料

用SiO2交联剂(SiO2HPA)交联甲基丙烯酸甲酯(MMA)自由基聚合制备PMMA SiO2纳米复合材料。采用两步法将可聚合乙烯基单体以化学键的形式键接到SiO2表面合成SiO2交联剂,首先利用过量的甲苯2,4二异氰酸酯(TDI)对SiO2纳米粒子表面进行化学修饰合成出表面带有高反应活性NCO基团的功能化SiO2粒子(SiO2TDI),SiO2TDI与丙烯酸羟丙酯(HPA)反应合成SiO2交联剂。系统研究了MMA单体与SiO2交联剂投料比及聚合时间对聚合反应的影响。此外,利用红外光谱(FT IR)、DSC、TGA、可见光光谱仪等实验手段对纳米复合材料进行了表征分析。结果表明,纳米SiO2粒子在复合材料中起着物理交联点和化学交联点作用,复合材料玻璃化转变温度(Tg)明显地高于其纯PMMA的玻璃化转变温度,随着纳米SiO2粒子含量的增加,复合材料玻璃化温度升高,而透明度明显降低。     

纳米SiO2的修饰改性及其在紫外光固化涂料中的性能研究

以对-甲基苯磺酸为催化剂，用丙烯酸羟乙酯和纳米SiO2进行酯化反应制备改性纳米SiO2用红外光谱仪和热失重分析仪对产物分析表明：纳米SiO2中约70．5％的Si-OH基团和丙烯酸羟乙酯发生了酯化反应。将改性前后的纳米SiO2应用于紫外光固化涂料中，研究了对涂料黏度和固化速率、涂料固化膜的铅笔硬度和耐磨性能等的影响。结果...     

辛醇改性纳米二氧化硅表面的研究

纳米粒子由于粒径小,所以具有很高的比表面积,表面原子处于高度活化状态,使得表面能很高,粒子易于团聚,填充未经表面处理的纳米粒子,不但起不到特殊作用,反而会成为复合材料的力学弱点。所以要对纳米粒子进行表面改性,提高分散性,增加纳米粒子与聚合物间的界面结合力。用醇类对许多粉体进行酯化反应是常用的表面改性方法。金属氧化物与醇的反应是酯化反应[1]。酯化反应修饰法对于表面为弱酸性和中性的纳米粒子最为有效,例如SiO2等。醇的羟基与SiO2的表面羟基发生反应脱掉一分子水,达到表面接枝的目的。方程式为:这样R基团接枝到SiO2的表面,由于R基团是亲油性的,从而增加了极性的SiO2纳米粒子与有机物的润湿性。为了推动反应正向进行,关键在于及时将产生的水份引出反应体系。目前国内外用醇对纳米粒子进行表面改性主要采用常规回流法和高压反应釜法[2]。由于微波照射具有对物质高效、均匀的加热作用,同时还具有电磁场对反应分子间行为的直接作用而引起的所谓“非热效应”,所以本实验采用微波照射法用正辛醇对SiO2纳米微粒进行表面酯化反应并与常规回流法进行比较。关于该方面的研究报道国内外较少。1实验部分1.1实验原料纳米SiO2:(10~20nm...     

二氧化硅-聚丙烯腈核-壳结构复合纳米粒子的制备与表征

以甲基丙烯酸-3-(三甲氧基硅基)丙酯改性的SiO2纳米粒子为种子,采用乳液聚合法制备了粒径分布较窄的SiO2-聚丙烯腈(SiO2-PAN)核-壳结构复合纳米粒子。采用动态光散射、傅里叶红外光谱、透射电镜和扫描电镜表征了复合纳米粒子的粒径及分布、组成、形态和结构,并研究了表面活性剂的加入方式、反应温度及交联剂的引入对制备SiO2-PAN复合纳米粒子的影响。结果表明:SiO2-PAN复合纳米粒子为核-壳结构。采用半连续加入表面活性剂的方法,可以成功抑制乳液聚合中次级粒子的生成。通过增加表面活性剂的初始加入量、加快表面活性剂的补加速率,或降低反应温度,可使SiO2-PAN复合纳米粒子的粒径变小。反应温度的降低以及交联剂的引入使SiO2-PAN复合纳米粒子的表面变得平滑。     

二氧化硅纳米粒子表面修饰及其表征

采用溶胶-凝胶法合成粒径在50—150nm范围内的二氧化硅（SiO2）纳米粒子。用甲基丙烯酸-3-（三甲氧基硅基）丙酯（MPS）对SiO2纳米粒子表面进行修饰,使其表面接枝能参与自由基聚合反应的碳碳双键基团。用元素分析、FTIR、^13C CP／MASNMR和^29Si CP／MASNMR等手段对修饰过的SiO2纳米粒子进行表征,以确证MPS接枝在SiO2纳米粒子上。分析修饰过的SiO2纳米粒子的^29Si CP／MASNMR和FTIR谱图,还可初步推断MPS接枝在SiO2纳米粒子表面的机理：MPS首先发生水解缩合反应形成低聚物,然后通过氢键作用吸附到SiO2纳米粒子表面,最后MPS低聚物中未缩合的硅羟基与SiO2纳米粒子表面的硅羟基发生缩合反应。     

尼龙6/SiO_2纳米复合材料的制备及其力学性能和热稳定性

以表面含有氨基的可反应性纳米SiO2(RNS-A)和表面含有烷基碳链的可分散性纳米SiO2(DNS-3)作为填料,利用原位聚合法制备了尼龙6/SiO2纳米复合材料(相应的复合材料分别简记为RPA和DP3);采用透射电子显微镜观察了复合材料中纳米SiO2的表面形貌,并利用热失重分析仪测定了复合材料的热稳定性,进而考察了纳米SiO2表面功能基团对尼龙6力学性能和热稳定性的影响.结果显示,纳米SiO2能够很好地分散在尼龙6基体中,并使尼龙6的热分解温度提高10℃左右.与此同时,RPA的最大拉伸强度和冲击强度较纯尼龙6的分别提高34.5%和12.5%,DP3的最大拉伸强度和冲击强度分别提高18.2%和45.7%.这表明两种纳米SiO2均可以有效地提高尼龙6的力学性能和热稳定性;可以推测,纳米SiO2的增强效应与其在尼龙6基体材料中的分散和界面作用有关.     

SiO2/PVAc无机-有机复合微球的合成及其膜性能研究

以纳米二氧化硅粒子(SiO2)为稳定剂,在少量反应型阴离子乳化剂——烯丙氧基羟丙磺酸钠(HAPS)作助稳定剂的情况下,制备了具有草莓型结构的二氧化硅/聚醋酸乙烯酯(SiO2/PVAc)无机-有机纳米复合微球.研究表明,纳米SiO2与PVAc的氢键作用是形成这种单分散草莓型SiO2/PVAc无机-有机纳米复合微球的关键.透射电镜(TEM)观察显示,纳米SiO2吸附在PVAc表面,形成草莓型结构.讨论了纳米二氧化硅溶胶的种类和用量、乳化剂种类对复合微球形态及其膜性能的影响,并讨论了复合微球的形成机理.     

对称性降低的SiO2/Ag核壳结构纳米粒子的制备及表面增强拉曼活性研究

采用湿化学还原法在自组装的单层阵列二氧化硅纳米粒子表面沉积银膜制备了SiO2核/Ag帽复合纳米结构。通过透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)和紫外-可见分光光度计(UV/Vis)研究和表征了该复合纳米结构的表面形貌、结构及光学性质。所制备的复合纳米粒子表面粗糙,其表面呈现无数纳米级谷粒状结构,SiO2内核粒径为350nm的银纳米帽的表面等离子共振吸收的2个共振峰分别位于382和689nm处。以亚甲基蓝作为探测分子研究了SiO2粒径为350和450nm的SiO2/Ag帽状复合纳米粒子的表面增强拉曼散射(SERS)活性,增强因子分别为3.6×109和3.9×109。结果表明,湿化学还原法制备的SiO2核/Ag帽复合纳米结构是很好的拉曼活性基底。     

纳米SiO2锚固光敏基团引发MMA光接枝聚合研究

对纳米SiO2进行了锚固光引发剂的表面修饰,进而引发甲基丙烯酸甲脂(MMA)光接枝聚合制备有机/无机复合粒子.纳米SiO2粒子首先用氯化亚砜进行表面氯化,再与光引发剂2-羟基-4-(2-羟基乙氧基)-2-甲基苯丙酮(Irgacure2959)反应从而锚固上光引发剂.通过紫外光引发MMA在经过修饰过的纳米SiO2表面上进行表面光接枝聚合.采用IR、TGA和TEM等方法表征了接枝前后纳米粒子的变化,证明了表面接枝物的存在,并研究了不同反应条件对单体转化率、接枝率和接枝效率的影响.研究结果表明,搅拌对接枝过程的影响比较显著.TGA结果显示未搅拌聚合时接枝率只能达到比较小的程度,而在搅拌条件下180min内MMA的接枝率可达到110%.     

Investigations of morphology of moisture‐cured silicone–urethanes

Results of studies on synthesis and properties of siloxane–urethane prepolymers as well as on selected properties of moisture‐cured silicone–urethanes have already been published. In this paper, some results of investigations of the effect of chemical structure of such silicone–urethane polymers on their phase seggregation investigated using mainly (TEM) transmission electron microscopy and small‐angle x‐ray scattering (SAXS) techniques are presented. It was found in TEM studies that in silicone‐urethanes obtained by moisture‐curing of NCO‐terminated prepolymers prepared from siloxane oligomer diols (SOD) and isophoronediisocyanate (IPDI), two factors determine the morphology of samples: length of siloxane chain and NCO/OH ratio. SAXS investigations showed that these silicone–urethanes had a lamellar structure. It was found that the long period of this structure changed from 4 to 9 nanometers as the siloxane chain length increased nine times. The increase of the long period correlated with the decrease of Young's modulus of the corresponding samples. TEM investigations of silicone–urethanes obtained by moisture‐curing of NCO‐terminated prepolymers prepared from the blends of SOD and polyoxypropylenediol (PPG) revealed complex morphology which depended on the SOD/PPG ratio. Copyright © 2000 John Wiley & Sons, Ltd.     

Investigation of ultraviolet curable waterborne polyurethane acrylate dispersion based on hydroxyl-terminated polybutadiene

A new kind of ultraviolet (UV) curable waterborne polyurethane acrylate dispersion was synthesized based on hydroxyl-terminated polybutadiene (HTPB), poly-(propylene glycol) (PPG), isophorene diisocyanate (IPDI), 2-hydroxy ethyl acrylate (HEA) and dimethylol propionic acid (DMPA) after neutralizing by triethylamine (TEA). 2-Hydroxy-1-[4-2-hydroxyethoxy) phenyl]-2-methyl-1-propanone (Irgacure 2959) was used as a photoinitiator and deionized water as a diluent. Fourier transform infrared (FTIR) analysis was used to identify the chain structure of the UV-curable polyurethane prepolymer based on HTPB and the curing process. Effects of relative content of HTPB and PPG on emulsion stability, resistance to water and ethanol, thermal stability, compatibility of soft and hard segment, as well as the mechanical property of the cured film were investigated. Translated from Polymer Materials Science and Engineering, 2006, 22(3): 199–203 (in Chinese)     

Synthesis of polyether‐based polyurethane‐silica nanocomposites with high elongation property

The NCO‐terminated prepolymers, prepared by reacting a mixture of poly(tetramethylene glycol) and fumed nanosilica with 4,4′‐diphenylmethane diisocyanate, were chain‐extended with 1,4‐ butanediol to yield polyurethane‐silica nanocomposites. The nanosilica particles were well dispersed in the polyurethane matrix up to 3 wt%. The polyurethane chains in the interfaces were covalently linked to the nanosilica surfaces through urethane bonds. Introduction of the nanosilica into the polyurethane enhanced both tensile strength and elongation of the resulting nanocomposite films. Especially, the elongation at break of the nanocomposite films containing 1 wt% nanosilica was 3.5 times greater than that of the pure polyurethane films. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis of a Novel Core-shell Type Acrylic-polyurethane Hybrid Emulsion Containing Siloxane and Fluorine as well as Water and the Oil Resistances of Cured Film

Aqueous acrylic-polyurethane dispersions have become one of the major types of materials used in coating, paint and adhesive industries, because of excellent properties and environmental advantages1-5. However, some properties for cured film such as water…     

异佛尔酮二异氰酸酯自聚产物的~(13)C-NMR研究

研究了用季铵盐N,N,N-三甲基-N-(2-羟基乙基)-氢氧化铵为催化剂时异佛尔酮二异氰酸酯(IPDI)自聚产物的合成,用13C-NMR1、H-NMR、不失真地极化转移增强(DEPT)1、3C-1H异核远程相关(HMBC)实验表征了产物结构.结果表明,自聚产物是三聚异氰酸酯,主要含有三聚体异氰脲基、异氰酸根.一维核磁谱及二维化学位移相关谱分辨出两种羰基,确定了氮上4种不同取代结构的分子链连接情况.对自聚产物的碳谱图进行了全归属.     

巯基-烯光点击反应辅助合成多官能度蓖麻油基聚氨酯丙烯酸酯

研究巯基-烯光点击反应辅助合成多官能度蓖麻油基聚氨酯丙烯酸酯。首先通过光引发的巯基-烯点击反应,于蓖麻油分子上引入巯基乙醇,形成多羟基化合物,然后加入丙烯酸羟丙酯与异佛尔酮二异氰酸酯,以物质的量为1:1反应得到端异氰酸酯丙烯酸酯,最终得到蓖麻油基聚氨酯丙烯酸酯。通过调节羟基含量可以得到不同官能度的丙烯酸酯。采用红外光谱、核磁氢谱、热重分析等手段表征其结构和性能,并测试了合成的聚氨酯丙烯酸脂的吸水率、附着力等性能,同时考察了它的热稳定性。结果表明, 在紫外光照射下,巯基和不饱和双键之间发生了加成反应;该聚合物的固化膜性能得到提高,尤其是硬度和热稳定性。由本文快速合成方法得到的树脂性能良好,具有较好的应用前景,扩大了巯基-烯光点击反应在高性能UV固化材料方面的应用范围。     

Facile preparation of superhydrophobic and oleophobic surfaces via the combination of Cu(0)‐mediated reversible‐deactivation radical polymerization and click chemistry

The fabrication of novel hydrophobic, superhydrophobic, and oleophobic surfaces on glass using nanosilica particles modified with polymer brushes prepared via surface initiated Cu(0)‐mediated reversible‐deactivation radical polymerization was demonstrated. Monomers including n‐butyl acrylate, 2,2,2‐trifluoroethyl methacrylate, and 1,1,1,3,3,3‐hexafluoroisopropyl acrylate were used to synthesize a series of nanosilica–polymer organic/inorganic hybrid materials. Products were analyzed using infrared spectroscopy, thermogravimetric analysis, scanning and transmission electron microscopy. The coated nanosilica showed core–shell structures that contains polymer brushes up to 67 wt %. The application of these particles for modifying surface wettability was examined by covalently attaching them to glass via a recently developed one‐pot “grafting to” methodology using “thio‐bromo click” chemistry. Atomic force microscopy topographic images show up to 25 times increase in roughness of the coated glass compared to blank glass sample. Contact angle measurements showed that nanosilica coated with PBA and PTFEM produced hydrophobic glass surfaces, while a superhydrophobic and oleophobic surface was generated using nanosilica functionalized with PHFIPA. This novel methodology can produce superhydrophobic and oleophobic surfaces in an easy and fast way without the need for tedious and time‐consuming processes, such as layer‐by‐layer deposition, high temperature calcination, and fluorinated oil infusion. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018     

Synthesis and characterization of hyperbranched polyesters and polyurethane coatings

Polyurethane (PU) coatings are widely used for variety of high‐performance applications in today's coating technology. The emerging hyperbranched polymers having three‐dimensional morphology have opened a new avenue to tailor the architecture of PU coatings. The methodology followed here is based on preparation of PU coatings from hyperbranched polyester. Initially, different hyperbranched polyester polyols (HPs) were synthesized by varying the hydroxyl‐terminated precursors that is, pentaerythritol, trimethylol propane or glycerol and keeping the diacid that is, adipic acid quantity constant at various mole ratios of 1:0.6, 1:0.8, 1:0.9, and 1:1, respectively. The obtained HPs were characterized by nuclear magnetic resonance (NMR) spectroscopy, matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF)‐mass spectrometry, and Fourier transform‐infrared (FTIR) spectroscopy. The degree of branching and the quantity of different structural units present in the various HPs were calculated by integrating the quaternary carbon and carbonyl zone in ¹³C NMR spectroscopy. The extent of condensation in different HPs was also calculated from ¹H NMR spectra. Later on, NCO‐terminated PU prepolymers (NCO‐PU) were synthesized by reacting HPs with isophorone diisocyanate (IPDI) at NCO/OH ratio of 1.6:1. In the third step, the excess NCO content in the NCO‐capped PU prepolymers were reacted with atmospheric moisture and hyperbranched polyurethane (HPU) coatings were formed. The coating films were analyzed by FTIR and dynamic mechanical thermal analysis instruments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2673–2688, 2007     

Synthesis and characterization of yellow water-borne polyurethane using a diol colorant as extender

<正>A novel and facile method toward a series of yellow water-borne polyurethane was developed by using an intrinsically colored diol in this paper.The yellow aqueous dispersion PCLD-HENA-PU was synthesized based on isophorone diisocyanate(IPDI), polycaprolactonediol(PCLD) and 2,2-dimethylol propionic acid(DMPA) using a yellow diol N,N-bis(2-hydroxyethyl)-4-nitroaniline (HENA) as a chain extender.Due to the complete reaction of OH group in colorant HENA with NCO group in diisocyanate,a series of stable yellow polyurethanes could be obtained conveniently and easily.The structure of PCLD-HENA-PUs was confirmed by means of Fourier transform infrared spectroscopy.The UV-visible absorption analysis showed a blue shift effect of about 7 nm when HENA was blocked into polyurethane chain.The absorption intensity of PCLD-HENA-PUs increased with increasing HENA content.It was found that the tensile strength enhanced from 8.6 to 19.6 MPa with HENA content increased from 0 to 18.0%,while the extensibility decreased from 449 to 300%.The thermal gravimetric analysis presented that the initial decompose temperature began from about 250℃,and had a little increase with increasing the HENA content.