甲基丙烯酸甲酯共聚物的超产特性研究

用超声脉冲回波法对甲基丙烯酸甲酯-甲基丙烯酸丁酯(MMA-BMA)、含交联剂的甲基丙烯酸甲酯-甲基丙烯酸(MMA-MAA)和苯乙烯-甲基丙烯酸(ST-MAA)等三类共聚物进行了超声衰减和声速实验研究.结果表明,随BMA含量的增加,MMA-BMA共聚物的超声衰减增大,而声速减小;交联剂的加入使共聚物MMA-MAA和ST-MAA的超声衰减明显增大.随着温度的升高,MMA-BMA的超声衰减单调缓慢增加,当温度上升到T_g时则急剧增大.T_g值随BMA的含量增加而降低.文章对上述结果给予了解释.     

电化学阻抗谱研究聚合物凝胶电解质对染料敏化太阳能电池性能的影响

用甲基丙烯酸β-羟乙酯(HEMA)与N-乙烯基吡咯烷酮(NVP)共聚物P(HEMA-NVP)、甲基丙烯酸甲酯(MMA)与N-乙烯基吡咯烷酮共聚物P(MMA-NVP)为原料制备了聚合物凝胶电解质, 用电化学阻抗谱(EIS)研究了聚合物凝胶电解质中聚合物基质的结构与组成对准固态染料敏化太阳能电池(DSSCs)光伏性能的影响. 不同交联剂用量、不同HEMA用量的P(HEMA-NVP)共聚物及不同MMA用量的P(MMA-NVP)吸收液态电解质后分别形成HGelI、HGelII、MGel凝胶电解质. 结果发现, 随共聚物P(HEMA-NVP)中交联剂由0.1%(w, 下同)增大到0.6%时, 形成的HGelI 组装的DSSCs的光电转化效率(η)先增大后降低, 交联剂用量为0.4%时, DSSCs的η为最大, 为5.54%(光强100 mW·cm^-2). 同时, 比较HGelII 系列和MGel 系列DSSCs的光电性能参数发现, 含有羟基的HGel 系列的η要高于MGel 系列, 而后者的开路电压(V_oc)值高于前者. 在HGelII 系列中, HEMA含量为60%(w)时, DSSCs的η最高. 电化学阻抗谱分析表明共聚物中交联结构的不同影响了电池内部的界面阻抗及离子的传输, 引入羟基有利于降低界面阻抗. 通过调整共聚物中交联剂用量和羟基含量可改善DSSCs的光伏性能.     

高聚物玻璃化转变温度和分子参数的关系 Ⅱ.分子量对玻璃化转变温度的影响

 根据前文提出的理论模型,本文推导出下述表征高聚物数均分子量(M_n)与玻璃化转变温度T₈关系的理论公式: T_g=T_g∞-K_g/M_n K_g=T_g∞·σ²(T_g)·M_u十几种高聚物的K_g理论计算位能较好地和实验值吻合。应用理论关系式具体计算了聚苯乙烯、聚氯乙烯、聚二甲基硅氧烷和聚α-甲基苯乙烯的T_g随分子量的变化,其结果是令人满意的。     

甲基丙烯酸甲酯-甲基丙烯酸正丁酯均聚共混物和无规共聚物的裂解色谱定量分析

聚甲基丙烯酸酯类是被广泛应用于工业、建筑、医疗等方面的一类塑料。人们曾经用多种方法对这类材料进行过分析和研究。甲基丙烯酸甲酯(MMA)-甲基丙烯酸正丁酯(BMA)共聚物和均聚共混物的裂解色谱鉴别和定量测定已有报道,但这些方法比较烦琐,不易做准,有的还不完善。本文对聚甲基丙烯酸甲酯(PMMA)-聚甲基丙烯酸正丁酯(PBMA)共混物(简称共混物)和MMA-BMA无规共聚物(简称共聚物)进行了裂解色谱定量研究,探讨了采用回归分析作出的工作曲线的定量方法,以及     

含碘聚甲基丙烯酸酯类X光显影材料的制备

由甲基丙烯酸正丁酯（BMA）与2-(2'-碘苯甲酰)-O-甲基丙烯酸乙酯(2-IEMA)自由基共聚制备了一种X光显影材料。1H NMR分析表明,该共聚物中2种结构单元之比与投料比吻合。GPC测得该共聚物的分子量随2-IEMA含量增加而降低。DSC分析表明,共聚物的玻璃化转变温度在22.3~28.0 ℃之间,与Fox方程计算值比较接近,而且随2-IEMA含量的增加而升高。TGA测得共聚物的分解温度为250 ℃,具有很好的热稳定性。力学性能测试结果表明,共聚物的拉伸强度随BMA含量的增加而增加,最大拉伸强度可达到7.46 MPa。X光显影性测试表明,该共聚物具有良好的显影性,显影效果随2-IEMA含量增加而增强。     

Ti0.17Zr0.08V0.34Nb0.01Cr0.1Ni0.3氢化物电极合金微观结构及电化学性能研究

采用XRD、FESEM-EDS、ICP及EIS等方法研究了Ti_0.17Zr_0.08V_0.34Nb_0.01Cr_0.1Ni_0.3氢化物电极合金微观结构和电化学性能。X射线衍射分析表明：该合金由体心立方结构(bcc)的V基固溶体主相和少量六方结构的C14型Laves相组成；FESEM及EDS分析表明：V基固溶体主相形成树枝晶，C14型Laves相呈网格状围绕着树枝晶的晶界，元素在两相中的分布呈现镜像关系。电化学性能测试结果表明：该合金的氢化物电极在303~343 K较宽的温度区间内，表现出较高的电化学容量，在303 K和343 K时，电化学容量分别为337.0 mAh·g^-1和327.9 mAh·g^-1。在303 K循环100周后，容量为282.7 mAh·g^-1。ICP分析结果表明，氢化物电极在充放电循环过程中，V及Zr元素向KOH电解质中的溶出较为严重。EIS研究表明，金属氢化物电极表面电化学反应的电荷转移电阻(R_T)随循环次数的增加而增加，相应的交换电流密度则随循环次数的增加而降低。氢化物电极循环过程中RT的增大以及V和Zr元素的溶解，可能是导致电极容量衰减的主要原因。     

丙烯酸共聚物囊壁的正十八烷微胶囊的制备和性能表征

以二丙烯酸1,4-丁二醇酯为交联剂, 成功制备了甲基丙烯酸甲酯-甲基丙烯酸共聚物为壁材, 正十八烷为囊芯的相变材料微胶囊. 采用扫描电子显微镜(SEM)、差示扫描量热仪(DSC)和热重分析仪(TG)分别考察了单体与芯材投料比、单体浓度和交联剂的含量对微胶囊形貌、相变热性能、热稳定性能的影响. 实验结果表明: 随着单体与芯材投料比或单体浓度的增加, 微胶囊表面均变得致密, 壁厚增加; 随着交联剂含量的增加, 微胶囊的表面变得更加致密光滑, 热稳定性显著增强; 随着单体与芯材投料比的增大, 微胶囊热焓值减小, 被包裹的囊芯含量减少.     

甲基丙烯酸甲酯-甲基丙烯酸无规共聚物的合成及其在乳液聚合中的应用

通过自由基共聚制备了不同组成的甲基丙烯酸甲酯-甲基丙烯酸无规共聚物,用碱中和后作为大分子乳化剂用于乳液聚合.研究了无规共聚物的组成、用量及反应温度对乳液聚合的影响.结果表明,在相同的反应条件下,乳化剂中聚甲基丙烯酸含量越多,乳液聚合速率越快;同一乳化剂,随乳化剂浓度的增加,乳液聚合速率增加;在乳化剂组成、浓度不变的情况下,反应温度越高,乳液聚合速率越大.     

退火条件对山梨醇玻璃焓松弛参数的影响

采用差示扫描量热法(DSC)测定山梨醇样品经历不同时间(t_a)等温退火后, 以10 K·min^-1速率进行升温时玻璃化转变温度(T_g)前后的比热容(C_p(T)). 将Gómez Ribelles (GR)提出的一种基于构型熵的现象学模型用于描述山梨醇玻璃的焓松弛行为, 考察GR模型能否适用于小分子玻璃体系. 结果表明, 单组GR模型参数拟合的曲线均能较好重现对应热历史条件下的山梨醇体系的实验所得C_p(T)曲线, 尽管并未找到不随热历史而变的一组参数作为材料常数, 但与其它现象学模型应用于小分子玻璃时, 其模型参数都随热历史变化而变化的特点相比, GR模型的某些参数基本保持不变. 且在较长退火时间下拟合得到的模型参数普适性较好. 同经历连续降温的山梨醇相比, 等温退火过程得到的松弛极限态参数(δ)的平均值与T_g处比热容增量(ΔC_p(T_g))的比值明显增大, 但仍小于聚合物的值, 表明GR模型提出的亚稳极限态对小分子玻璃的影响值得商榷.     

ABg型缩聚形成的超支化聚合物的支化度与分子形态

用聚合反应动力学模型, 详细分析了AB_g型缩聚体系中各种结构单元的演变, 对超支化聚合物支化度的各种定义作了比较, 并对AB_g型反应体系的支化度提出了一个改进的定义, 使得支化度随g的增加而增加, 当g从2增加到无穷大, 最大支化度相应地从0.5增加到1－e^－1. 对均方回转半径的数值计算表明, 在确定的A基团转化率(x), z-均均方回转半径几乎与g无关, 当x＝0.999时, 随着g从2增加到无穷大, z-均回转半径只增加0.1%. 但是, 同样的条件下, z-均聚合度增加到2倍. 这一现象表明在任何指定的A转化率, AB_g型缩聚中形成的超支化聚合物的分子轮廓与g无关, 随着g 增大而在超支化聚合物中增加的结构单元(或聚合度)必定分布在分子内部.     

Photocatalytic degradation of methyl methacrylate copolymers

The photolytic and photocatalytic degradation of the copolymers poly(methyl methacrylate-co-butyl methacrylate) (MMA-BMA), poly(methyl methacrylate-co-ethyl acrylate) (MMA-EA) and poly(methyl methacrylate-co-methacrylic acid) (MMA-MAA) have been carried out in solution in the presence of solution combustion synthesized TiO₂ (CS TiO₂) and commercial Degussa P-25 TiO₂ (DP 25). The degradation rates of the copolymers were compared with the respective homopolymers. The copolymers and the homopolymers degraded randomly along the chain. The degradation rate was determined using continuous distribution kinetics. For all the polymers, CS TiO₂ exhibited superior photo-activity compared to the uncatalysed and DP 25 systems, owing to its high surface hydroxyl content and high specific surface area. The time evolution of the hydroxyl and hydroperoxide stretching vibration in the Fourier transform-infrared (FT-IR) spectra of the copolymers indicated that the degradation rate follows the order MMA-MAA > MMA-EA > MMA-BMA. The same order is observed for the rate coefficients of photocatalytic degradation. The photodegradation rate coefficients were compared with the activation energy of pyrolytic degradation. In degradation by pyrolysis, it was observed that MMA-BMA was the least stable followed by MMA-EA and MMA-MAA. The observed contrast in the order of thermal stability compared to the photo-stability of these copolymers was attributed to the two different mechanisms governing the scission of the polymer and the evolution of the products.     

OPTICAL PROPERTIES OF IPN-LIKE NETWORKS. II. POLYETHYLENE/POLY-(BUTYLMETHACRYLATE-CO-METHYLMETH-ACRYLATE) COPOLYMER SYSTEMS

IPN-like systems, made of Poly[butylmethacrylate(BMA)-co-methylmethacrylate (MMA)] copolymers and Low Density Polyethylene (PE) networks, were synthesized by a procedure described in previous papers.

The initial PE/copolymer molar ratio was kept constantly equal to one for all the samples. Different molar BMA/MMA copolymer ratios (50/50, 60/40, 80/20, 90/10 100/0) and a molar percentage of 1.0% of the copolymer crosslinker, 1,4-Butandioldimethacrylate (BDDM), were used.

The samples obtained were analyzed by DSC, WAXS, swelling in CCl₄, and dynamic-mechanical tests. PE crystallinity was lowered by the network formation and slightly increased, whereas, the overall network density decreased, with enhancing the BMA content.

Optical investigations were performed in a temperature range between room temperature (R.T.) and 180°C, using MMA as comonomer of BMA, instead of Styrene (S), as well as a different crosslinker (BDDM instead of DVB).

All the IPN's showed the matching-mismatching optical transition of R.I., with temperatures corresponding to a transparency condition. The larger the BMA content, in the initial reactant MMA-BMA comonomeric mixture, the higher such temperatures. An analytical expression was found relating this temperature to the copolymer composition.     

氟硅协同改性丙烯酸树脂的合成与防污性能研究

以甲基丙烯酸十二氟庚酯(FMA)、甲基丙烯酸聚二甲基硅氧烷基酯(SMA)、甲基丙烯酸甲酯、丙烯酸正丁酯、甲基丙烯酸正丁酯和丙烯酸乙酯为共聚单体,通过溶液聚合反应合成出侧链含有机氟、有机硅的丙烯酸树脂.通过核磁共振氢谱(1H-NMR)、核磁共振氟谱(19F-NMR)、红外光谱(FTIR)对聚合物的结构进行了表征.通过扫描电镜(SEM)、接触角测试和生物评价等方法,探讨了FMA、SMA含量对树脂涂膜性能的影响.结果表明氟硅改性的丙烯酸树脂比单独含氟或含硅改性的丙烯酸树脂具有更低的表面能,而且氟硅改性的丙烯酸树脂涂膜比商业化的聚硅氧烷涂膜具有更好的防污性能.     

丙烯酸酯共聚物无皂水溶胶稳定性的研究

用溶液聚合法合成了四种AA含量不同的丙烯酸酯共聚物(MMA/BA/HEMA/AA)，通过中和AA使共聚物带有—COO~-能起自乳化作用分散于水中而成为无皂水溶胶．TEM观察表明水溶胶粒子呈球状，单分散性好，粒径随AA含量增加而变小，在30～90 nm范围．用电导滴定法测定水溶胶粒子中—COOH和—COO~-的分布，表明绝大部分—COO~-处于粒子表面，并且随AA含量增加，粒子表面的—COO~-增多，Zeta电位增大，这是导致水溶胶的抗电解质稳定性(以C.C.C.值反映)和贮存稳定性(以表现粘度反映)随AA含量增加而提高的主要原因。     

Preparation,characterization and application of maleic anhydride-modified polylactic acid macromonomer based on direct melt polymerization

A one-pot two-step method based on direct melt polymerization (DMP) for the synthesis of polylactic acid (PLA) macromonomer and its further functionalized application has been developed. The first stage of the reaction is a copolycondensation of lactic acid (LA) and maleic anhydride (MAH) to obtain the macromolecule poly(lactic acid-co-maleic anhydride) (PLAM) with reactive double bonds, and the second stage is a radical copolymerization of different acrylates with PLAM to afford the modified PLA functional materials. The influences of the acrylates have been investigated. The results show that the species with substituted methyl groups in acrylate can polymerize relatively stable. On the other hand, the more carbon atoms in the ester segment of acrylate, the higher intrinsic viscosity [η] and terminal decomposition temperature for the acrylate-modified PLAMs. Among six kinds of acrylates used as the third monomer, such as acrylic acid (AA), methyl acrylate (MA), butyl acrylate (BA), methacrylic acid (MAA), methyl methacrylate (MMA), and butyl methacrylate (BMA), the BMA-modified PLAM has the biggest [η] (0.7566 dL/g) and the terminal decomposition temperature (418 °C) for there are more carbon atoms in BMA. Due to excellent reactivity of the intermediate PLAM, the final modified product can have the anticipated properties for the PLA material by the controllable regulating as different purposes. Thus, this strategy as a green and simple method provides well application prospect for PLA materials in industrial plastics, biomedicine etc.     

Enhancing the flame-retardant and smoke suppression properties of transparent intumescent fire-retardant coatings by introducing boric acid as synergistic agent

A series of novel phosphorus-boron flame retardants (BPEAs) were successfully synthesized by introducing boric acid (BA) into cyclic phosphate ester acid (PEA) via the esterification and thoroughly characterized by ¹H nuclear magnetic resonance spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Five kinds of transparent fire-retardant coatings applied to wood substrates were produced by thoroughly mixing amino resin with PEA and BPEAs. The effects of BA on the optical transparency, thermal stability, fire performance and smoke emission characteristics of the coatings were investigated by various analytical instruments. The transparency analysis reveals that the transparency value of the coatings gradually decreases with increasing BA loading, and MPEA4 with the highest BA content still exhibits a high degree of transparency. The results from fire protection, cone calorimeter and smoke density tests show that the introduction of BA greatly decreases the flame spread rating, mass loss, char index, heat release rate, smoke production rate, total heat release, total smoke release and specific optical density of the coatings concomitant with the increase in the residual mass and intumescent factor, which is ascribed to the formation of a more dense and continuous intumescent char judging by digital photographs and scanning electron microscope images. Thermo-gravimetric analysis indicates that the onset decomposition temperature, high-temperature stability and residual mass of the coatings greatly improve with increasing BA content. FTIR analysis shows that the introduction of BA into the coatings contributes to generate more phosphorus-rich cross-linked structures and aromatic structures and then create a compact and intumescent char layer, thereby effectively enhancing the flame retardancy and smoke suppression properties of the coatings.     

STRUCTURE AND PROPERTIES OF P(MMA-MAA)/PEO INTERMACROMOLECULAR COMPLEX FORMED THROUGH HYDROGEN BONDING

The superstructure and properties of polymers might be improved and enhanced througl intermolecular complexation. In this paper, the preparation, structure and properties of P(MMA-MAA)/PEO intermolecular complex through hydrogen bonding are studied. By acid hydrolysis of PMMA, a series of P(MMA-MAA) copolymers have been prepared, the MAA content of which depends on the temperature and time of hydrolyzation. In case the MAA content in P(MMA-MAA) is beyond 0.4 mole fraction, the hydrogen bonding between P(MMA-MAA) and PEO is strong enough to form intermolecular complex. The supermolecular structure of the complex is quite different from that of its constituent, which was observed by an X-ray diffraction and transmission electron microscope. The crystallization of PEO is confined owing to complexation. The complex exhibits quite a lot of good properties in thermal stability, gas permeability as well as mechanical strength, and could be used in many fields.     

含疏水链节的聚N-异丙基丙烯酰胺共聚物的温敏性

采用溶液聚合法合成了一系列N-异丙基丙烯酰胺(NIPAM)与甲基丙烯酸甲酯、丙烯酸乙酯、丙烯酸丁酯或甲基丙烯酸丁酯的无规共聚物,用浊度观测法和光散射法测定了不同共聚物水溶液的温敏相转变行为.结果表明:所得共聚物的低临界溶解温度(LCST)均低于均聚物PNIPAM的,酯类单体的结构和含量对共聚物的LCST有显著影响,其中酯基上的烷基对共聚物LCST的影响能力大于丙烯酸酯α位上的烷基,前者对增大共聚物的疏水性有更大贡献.通过NIPAM与特定丙烯酸酯单体进行无规共聚可以合成转变温度低于PNIPAM均聚物且具有预设LCST数值的水溶性温敏聚合物.     

Influence of Emulsifiers on Acrylate Latex Blends

The poly(methyl methacrylate/butyl acrylate/acrylic acid) [P(MMA/BA/AA)] and poly (styrene/butyl acrylate/acrylic acid) [P(St/BA/AA)] latexes were synthesized using the emulsifier octylphenol polyoxyethylene(10) ether (OP-10) and ammonium sulfate allyloxy nonylphenoxy poly(ethyleneoxy)(10) ether(DNS-86). The optimum amount of OP-10 and DNS-86 was 1.5% and 2.5% respectively. The P(MMA/BA/AA) and P(St/BA/AA) latex containing 1.5% OP-10 or 2.5% DNS-86 were blended pairwise. The performances of latex blends and parent latexes as a function of emulsifiers content in parent latexes were determined. The results indicated that the stability of latex blends is favorable, and particle size distribution was more uniform and thermal stability was improved after blending.