甲基丙烯酸甲酯-丙烯酸乙酯辐射共聚物的NMR研究

用¹H NMR,¹³C NMR,DEPT,gHMBC 和gHSQC 等一维、二维谱研究了γ 射线辐射引发聚合的甲基丙烯酸甲酯(MMA)与丙烯酸乙酯(EA)共聚物的微观化学结构并作了归属．结果表明二种单体的聚合转化率都较高,共聚物中MMA含量略多一些．由羰基碳的共振信号测得的共聚物中单体链节的三元组含量表明,在共聚物主链结构以嵌段分布为主,这是由于MMA与EA的竟聚率差异所致．     

甲基丙烯酸甲酯-萘乙烯共聚物的核磁共振研究──1.甲基丙烯酸甲酯-萘乙烯共聚物的2D NMR谱研究

用500MHz超导核磁共振谱仪测定了甲基丙烯酸甲酯-萘乙烯共聚物的二维异核多量子化学位移相关谱和二维相敏NOESY谱，由此归属了共聚物的碳谱和氢谱，结果表明，聚合物是以无规共聚物为主，其中有一部分是以头一头（或尾一尾）相接的．文中还以反门控去偶测得其共聚含量．     

红外光谱法测定固相微萃取新型吸附质中单体的摩尔比

以丙烯酸丁酯和苯乙烯为单体 ,过氧化苯甲酰为引发剂 (用量为wt 0 3% ) ,醋酸丁酯和甲苯作混合溶剂 ,溶剂用量与单体混合物的体积相同 ,采用溶液聚合的方法合成了一种新型固相微萃取吸附质 (苯乙烯 丙烯酸丁酯共聚物 )。以朗伯 比耳定律为依据 ,通过一系列的推导过程 ,得出了共聚物中两种官能团的吸收值比与共聚物中两种单体摩尔比的线性关系式A1 /A2 =kn1 /n2 。采用红外光谱法测定聚合物中两种官能团的吸收值比 ,再通过外标曲线法确定了共聚物中两种官能团的吸收值比 (y)与共聚物中两种单体的摩尔比 (x)的线性回归方程 y =0 136 2 0 0 84 1x。方法的精密度RSD(% ) =2 4 6 4 ,方法的回收率为 92 89%～10 3 94 %。红外光谱法测定作为固相微萃取新型吸附质的苯乙烯与丙烯酸丁酯共聚物中单体的摩尔比是一种快速准确的分析方法     

甲基丙烯酸甲酯-萘乙烯共聚物的核磁共振研究——I.甲基丙烯酸甲酯-萘乙烯共聚物的2D NMR谱研究

用500MHz超导核磁共振谱仪测定了甲基丙烯酸甲酯-萘乙烯共聚物的二维异核多量子化学位移相关谱和二维相敏NOESY谱,由此归属了共聚物的碳谱和氢谱,结果表明,聚合物是以无规共聚物为主,其中有一部分是以头-头(或尾-尾)相接的.文中还以反门控去偶测得其共聚含量.     

苯乙烯-丙烯酸丁酯共聚物的红外光谱定量测定

苯乙烯(St)与丙烯酸丁酯(BA)制成的共聚物树脂是常用的涂料之一,其特性取决于共聚物的组成,改变配方的组成可有效地控制涂层的硬度、柔韧性、冲击强度、保光保色以及抗水抗油等性能。作为苯乙烯的定量峰,可采用700cm~(-1)和1600cm~(-1)吸收峰。前者系单取代苯环CH面外弯曲振动吸收,后者为苯环伸缩振动吸收。我们的实验表明,1600cm~(-1)吸收峰比之700cm~(-1)峰更适用于苯乙烯的定量。作为丙烯酸丁酯的定量峰,可选用表征酯羰基伸缩振动的1733cm~(-1)吸收峰。用薄膜法制样和吸光度比的方法,可定量测定共聚物的组成,并根据测定结果计算两单体的竞聚率。     

BP神经网络-FTIR方法测定苯乙烯-丙烯酸丁酯共聚物中单体含量

利用红外特征峰波数偏移值与单体含量间的非线性定量关系,BP人工神经网络-FTIR法在较宽的含量范围(10%-90%之间)之内,准确测定了苯乙烯-丙烯酸丁酯共聚物中丙烯酸丁酯单体含量,回收率在97.3%-101.8%之间.     

乙丙共聚物的组成和序列分布的红外光谱测定

用红外光谱法测定了乙丙共聚物的组成和序列分布.以无规聚丙稀作标样,所得吸光度方程测定乙丙共聚物的组成的平均相对误差在±1.57％。选用无规聚丙稀、2,5-二甲基已烷、鲨烷和正十四碳烷作模型化合物测定乙丙共聚物的序列分布,所建立的吸光度方程组的系数与文献值一致。     

苯乙烯和马来酸酐共聚物的13C NMR谱解析和分子链结构表征

通过比较高温110 ℃下特定苯乙烯-马来酸酐共聚物H10和常温紫外辐照特定共聚合的苯乙烯-马来酸酐共聚物UV4的¹³C质子去偶谱和DEPT135谱，总结给出共聚
物链中马来酸酐环中酸酐基的取代效应参数（α=13.5、β=2.5、γ=-2）及引用苯基取代参数：α=16、β=6、γ=-2，对共聚物主链碳的化学位移进行了经验计算，对所有碳，尤其是主链碳在三单元组或四单元组水平上进行了链序列结构归属. 在进行峰面积积分的基础上，对共聚物分子链两种组份摩尔比或摩尔含量、交替度、链嵌段长度、马来酸酐环残基中顺反异构体比和共聚物数均分子量等进行了表征. 共聚物UV4比H10的交替度高许多，表明聚合温度对苯乙烯和马来酸酐共聚合交替链结构的形成有重要影响.     

准一维共聚物的电子结构研究

在紧束缚近似下,建立了共聚物 (- PPP_x )—( PA_y)- 的物理模型,研究了组成共聚物的均聚物单体对体系晶格结构、能带结构等的影响,发现共聚物的带隙可通过改变均聚物的配比或均聚物之间的相互作用来加以调制. 关键词： 共聚物 界面耦合 带隙     

碳纳米管束中的正电子理论

采用中性原子叠加模型和有限差分方法(SNA-FD)计算了大范围内不同管径的单壁碳纳米管束中的正电子情况，发现对于单壁碳纳米管束，正电子的主要湮没区域，湮没对象和正电子寿命随碳纳米管管径的不同而发生规律性变化.计算得到管径范围在0.8—1.6nm的碳纳米管束的正电子寿命范围为332—470ps，与实验测得的394ps符合较好.     

Investigation of Pendant Group and Chain Segment Motions in P(MMA/BA) Copolymers by Thermally Stimulated Depolarization Current

Poly(methyl methacrylate/butyl acrylate) [P(MMA/BA)] copolymers (M_η ～2×10⁵) with different mass percentages of MMA were synthesized by the method of solution polymerization. Thermally stimulated depolarization current (TSDC) technique was used to investigate the effect of copolymerization on pendant group and chain segment motions. Three TSDC peaks were observed over the temperature range from 310 to 400 K. The highest temperature, ρ peak originates from the detrapping of trapped charge carriers. The lower temperature, α peak corresponds to the glass transition. The activation energy of the α relaxation decreases from 1.2 eV for PMMA to 0.98 eV for MMA(75)/BA(25). In the fitting process, another peak, β′, is separated on the low temperature side. The apparent energy barrier of the β′ for PMMA is 0.80 eV. The β′ relaxation is thought to correspond to the motion of pendant groups including intra‐ and inter‐molecular interactions. All three peaks move to lower temperatures with an increase in BA component, and the activation energy for the α and β′ relaxations also decreases with the increase of BA component in copolymers, indicating that the flexible side groups of BA have an effect of plasticization on the glass transition and motion of pendent groups. The temperatures of the α and β′ peaks of P(MMA/BA) copolymers follow the Fox equation. Fitting results gives the α peak at 238 K and β′ peak at 225 K for polybutyl acrylate (PBA).     

Polyethylene-supported poly(methyl methacrylate<Emphasis Type="Italic">-co-</Emphasis>butyl acrylate)-based novel gel polymer electrolyte for lithium ion battery

A new copolymer, poly(methyl methacrylate-co-butyl acrylate) (P(MMA-co-BA)), was synthesized by emulsion polymerization with different mass ratio of methyl methacrylate (MMA) and butyl acrylate (BA). The membranes were prepared by phase inversion and corresponding gel polymer electrolytes (GPEs) were obtained by immersing the membrane into a liquid electrolyte. In this design, the hard monomer MMA provided the copolymer with good electrolyte uptake, while the soft monomer BA provided the GPE with strong adhesion between the anode and cathode of lithium ion battery. The properties of the resulting product were investigated by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectra, scanning electron spectroscopy, linear sweep voltammetry, thermogravimetric analysis, cyclic voltammetry, electrochemical impedance spectroscopy and charge/discharge test. The results show that the obtained GPE based on P(MMA-co-BA) with the mass ratios of MMA and BA = 6:1 exhibits good conductivity (as high as 1.2 × 10^?3 S cm^?1) at room temperature and high electrochemical stability (up to 4.9 V vs. Li/Li⁺). With the application of the polyethylene (PE)-supported GPE in Li/Li(Li_0.13Ni_0.30Mn_0.57)O₂ battery, the battery presents good cyclic stability (maintaining 95.4 % of its initial discharge capacity after 50 cycles) at room temperature.     

Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results.     

Liquid–Liquid Transition and Detrapping of Trapped Carriers of P(MMA/BA) Copolymers by Thermally Stimulated Depolarization Current

Poly (methyl methacrylate/butyl acrylate) [P(MMA/BA)] copolymers (M _η～2×10⁵) with different mass percentages of PMMA (100/0, 90/10, 81/19, and 75/25), were synthesized by the method of solution polymerization. In addition to the normal α and ρ peak, a third τ peak is observed in thermally stimulated depolarization current (TSDC) spectra of the copolymers in the high temperature region. The α peak‐corresponds to the glass transition, the ρ peak originates from the detrapping of trapped carriers in the bulk amorphous structure related with flexible side groups, and the τ peak can be attributed to the charge detrapping related to the liquid–liquid transition of the copolymers. The three peaks all move to lower temperature with an increase of the BA component, indicating that the flexible side groups of butyl acrylate not only have an effect of plasticization on the glass transition and liquid–liquid transition, but also make the trap depth shallower and the detrapping process easier for the ρ and τ peaks. The experimental results confirm that TSDC analysis is very sensitive for investigating the liquid–liquid transition of polymers. The liquid–liquid transition temperature (T _LL) of the copolymers follows a type of the Fox equation. Fitting the results gives a T _LL of 102°C for polybutyl acrylate.     

Effect of Surfactant Type and Concentration on Surfactant Migration,Surface Tension,and Adhesion of Latex Films

The effect of surfactant type and concentration on the migration behavior of surfactant in a latex film was investigated. Two types of surfactant, including an anionic (sodium lauryl sulfate, SLS) and a non-ionic (nonylphenol ethoxylate, average number of ethylene oxide units = 40, NP-40) surfactant, were used in an emulsion polymerization of methyl methacrylate butyl acrylate copolymer (MMA–BA). The total amount of surfactant was varied in three levels, i.e., 1.5, 3, and 4.5 wt%, and the surfactants were used both pure and in a mixture state. The surfactant migration to the film–air (F–A) and film–substrate (F–S) interfaces of the latex films was determined by using an attenuated total reflection-Fourier transform infrared (ATR-FTIR) method. In addition, the adhesion of the latex films to glass substrates was measured by a pull-off test. The results showed that the migration of anionic surfactant to the interfaces was greater than the non-ionic one. It was also found that the use of non-ionic surfactant along with anionic surfactant could decrease the migration of the anionic surfactant to the interfaces.     

Kinetic approach to modeling the radical polymerization of butyl acrylate in the presence dibenzyl trithiocarbonate

A mathematical model of the kinetics of the radical polymerization of butyl acrylate in the presence of dibenzyl trithiocarbonate by the reversible addition-fragmentation chain transfer mechanism with cross-termination of radicals and intermediates and quadratic termination of intermediates. The viability of the polymerization mechanism underlying the model and the related mathematical formalism are tested by comparing the calculated and measured values of the average molecular-weight characteristics of resulting poly(butyl acrylate).     

Ultrasound-assisted synthesis of poly(MMA–co–BA)/ZnO nanocomposites with enhanced physical properties

The present study reports synthesis and characterization of poly(MMA–co–BA)/ZnO nanocomposites using ultrasound-assisted in-situ emulsion polymerization. Methyl methacrylate (MMA) was copolymerized with butyl acrylate (BA), for enhanced ductility of copolymer matrix, in presence of nanoscale ZnO particles. Ultrasound generated strong micro-turbulence in reaction mixture, which resulted in higher encapsulation and uniform dispersion of ZnO (in native form – without surface modification) in polymer matrix, as compared to mechanical stirring. The nanocomposites were characterized for physical properties and structural morphology using standard techniques such as XRD, FTIR, particle size analysis, UV–Visible spectroscopy, electrical conductivity, TGA, DSC, FE-SEM and TEM. Copolymerization of MMA and BA (in presence of ZnO) followed second order kinetics. Thermal stability (T_10% = 324.9 °C) and glass transition temperature (T_g = 67.8 °C) of poly(MMA-co-BA)/ZnO nanocomposites showed significant enhancement (35.1 °C for 1 wt% ZnO and 15.7 °C for 4 wt% ZnO, respectively), as compared to pristine poly(MMA–co–BA). poly(MMA–co–BA)/ZnO (5 wt%) nanocomposites possessed the highest electrical conductivity of 0.192 μS/cm and peak UV absorptivity of 0.55 at 372 nm. Solution rheological study of nanocomposites revealed enhancement in viscosity with increasing ZnO loading. Maximum viscosity of 0.01 Pa-s was obtained for 5 wt% ZnO loading.     

Preparation of magnetic poly(methylmethacrylate–divinylbenzene–glycidylmethacrylate) microspheres by spraying suspension polymerization and their use for protein adsorption

Moderately uniform magnetic poly(methylmethacrylate–divinylbenzene–glycidylmethacrylate) microspheres (poly(MMA–DVB–GMA) microspheres) were prepared by spraying suspension copolymerization of methyl methacrylate, divinylbenzene and glycidyl methacrylate in the presence of Fe₃O₄ magnetic fluid. A protein adsorption assay indicated that these magnetic microspheres could significantly improve the capacity of protein adsorption.     

Preparation of BA/ST/AM nano particles by ultrasonic emulsifier-free emulsion polymerization

A kind of nano particle of butyl acrylate (BA)/styrene (ST)/acrylamide (AM) was prepared through a new method that was ultrasonic emulsifier-free emulsion polymerization, which was a kind of environmental protection and economical method. And no any volatile organic solvent (VOC), emulsifier and initiator were used in this method. Only water was used as solvent. The effects of sonic intensity, sonic time, inorganic salt content, N2 flow velocity, etc. on monomer conversion were studied. TEM photographs showed that its particles size was about 80 nm, which was less than particles size (about 140 nm) through conventional emulsifier-free emulsion polymerization method. The FTIR spectrum showed that after extracted by water for 48 h, CHCl3 for 48 h and THF for 48 hr, respectively, the sample obtained by this way was a ternary copolymer of BA, ST and AM, but not a blend of poly(butyl acrylate), polystyrene and polyacrylamide.     

IR-UV联合法测定固相微萃取涂层中单体含量

合成了作为固相微萃取涂层的苯乙烯-丙烯酸丁酯-乙烯基三乙氧基硅氧烷三元共聚物。采用红外光谱(IR)和紫外光谱(UV)相结合的方法测定了聚合物中苯乙烯和丙烯酸丁酯的含量。由IR法测得样品中二者的摩尔比。采用双波长紫外光谱法测得苯乙烯的含量。由苯乙烯与丙烯酸丁酯的摩尔比及苯乙烯的含量得出样品中丙烯酸丁酯含量,进而得出乙烯基三乙氧基硅氧烷的含量。苯乙烯与丙烯酸丁酯的摩尔比测定的外标曲线方程为A_r=0.114m_r+0.032,相关系数r2=0.999 3;苯乙烯含量测定的标准曲线方程为ΔA=0.078 6c+0.081 2,相关系数r2=0.998 9。苯乙烯含量测定的相对标准偏差(RSD)为0.41%,加标回收率为97.8%～104.0%;丙烯酸丁酯含量测定的相对标准偏差(RSD)为0.39%,加标回收率为97.1%～99.6%。