Two‐dimensional NMR studies of styrene/n‐butyl acrylate copolymers synthesized by atom transfer radical polymerization

Copolymers of styrene and n‐butyl acrylate were prepared by atom transfer radical polymerization (ATRP) using CuBr/N,N,N′,N′,N″‐pentamethyl‐diethylenetriamine as catalyst and Methyl 2‐bromopropionate as initiator. The polydispersity of the copolymers is quite low (1.1–1.3). ¹³C {¹H} NMR spectra of these copolymers show that the methylene and methine signals of the main chain are compositional sensitive and highly overlapped. Even the distortionless enhancement by polarization transfer (DEPT) was not able to assign the complex and overlapping signals. Assignments of the various resonance signals were done with the help of heteronuclear single quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple bond correlation (HMBC) experiments. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

聚丙烯蜡接枝甲基丙烯酸和苯乙烯接枝率的测定

考查了聚丙烯蜡接枝甲基丙烯酸、苯乙烯反应中,不同接枝率的红外特征峰的变化规律。通过特征峰比值和化学滴定所测接枝率值的线性回归,建立了相应的半定量经验方程式,建立了用红外法对聚丙烯蜡的接枝率进行半定量分析的方法,     

Thickening of butyl acrylate/styrene/2-hydroxyethyl methacrylate/acrylic acid lattices with dispersion of crosslinked ethyl acrylate/methacrylic acid copolymer

Thickening of lattices of styrene–acrylic copolymers containing a small amount of acrylic acid and various amounts of 2-hydroxyethyl methacrylate (HEMA) with alkali-swellable dispersion of crosslinked ethyl acrylate/methacrylic acid copolymer has been studied using capillary viscometry and dynamic and steady shear measurements. The higher the amount of HEMA incorporated into the latex copolymers, the stronger the thickening effect is. A comparison of flow behavior of thickened systems with those of neat lattices confirmed a significant influence of the effective volume fraction of alkalinized swollen latex particles on the thickening process. Under these conditions, to obtain the same rheological properties, the necessary amount of thickener was lower for the latex copolymers with higher amounts of HEMA because a part of the thickener volume fraction was replaced by an increased volume fraction of swollen latex particles. These findings indicate weakly interacting dispersion systems without strong compression of particle domains.     

聚甲基丙烯酸-苯乙烯-甲基丙烯酸的合成

以萘钠为引发剂双向引发活性阴离子聚合制备嵌段共聚物聚甲基丙烯酸叔丁酯-苯乙烯-甲基丙烯酸叔丁酯(PTBMA—PS—PTBMA)，并在碱性条件下水解合成了ABA型两亲嵌段共聚物聚甲基丙烯酸-苯乙烯-甲基丙烯酸(PMAA—PS—PMAA)。对产物进行了傅立叶红外光谱分析，热分析及凝胶色谱分析。当苯乙烯与α-甲基丙烯酸叔丁酯投料质量比为54：46时，所得共聚物相应嵌段质量比为79：2l左右。     

13C NMR spectral assignments of methacrylic acid/acrylonitrile statistical copolymers

Copolymerization of methacrylic acid (M) and acrylonitrile (A) in bulk at 60°C gives a statistical copolymer. Through the use of ¹H, ¹³C, DEPT and twodimensional NMR techniques, the observed resonances in the NMR spectra of these copolymers can be assigned, and thus provide detailed information about the microstructure of the polymer at the diad, triad and tetrad levels. Configurational effects have also been shown to play an important role, although in all cases the chemical shift differences resulting from configurational variation are smaller than those resulting from sequence variation.     

Microstructure analysis of N‐vinyl‐2‐pyrrolidone/vinyl acetate copolymers by NMR spectroscopy

N‐Vinyl‐2‐pyrrolidone (V) and vinyl acetate (A) copolymers of different compositions were synthesized by free radical bulk polymerization. The copolymer composition of these copolymers was determined using quantitative ¹³C{¹H} NMR spectra. The reactivity ratios for these comonomers were determined using the Kelen–Tudos (KT) and non‐linear least‐square error‐in‐variable (EVM) methods. The reactivity ratios calculated from the KT and EVM methods are r_V = 2.86 ± 0.16, r_A = 0.36 ± 0.09 and r_V = 2.56, r_A = 0.33, respectively. ¹H, ¹³C{¹H} and ¹H–¹³C heteronuclear shift correlation spectroscopy (HSQC) and ¹H–¹H homonuclear total correlation spectroscopy (TOCSY) were used for the compositional and configurational assignments of V/A copolymers. The ¹³C distortionless enhancement by polarization transfer (DEPT) technique was used to resolve the methine, methylene and methyl resonance signals in the V/A copolymers. © 2002 Society of Chemical Industry     

Studies on conformational transition of the maleic acid copolymer with styrene in aqueous salt solution by derivative spectroscopy

The first and second derivative spectra for the optical absorption of maleic acid copolymer with styrene were measured in aqueous 0.09 m NaCl at 25°C within a wavelength range of 240–280 nm, where contributions of groups, other than the phenyl ones, to the second derivatives seem to be negligible. The normal absorption spectra in the range were composed of seven absorption bands and the peak position of each band was determined from the derivative spectra. The peak position of the coiled form copolymer was found to shift to the shorter wavelength range compared with the compact form of the copolymer. From the extent of such blue shifts for each peak, the environment near the phenyl groups in the compact copolymer form was concluded to be similar to aqueous ethanol (40–50 vol%), by comparing with the derivative spectra for $\text{N-}\text{acetyl-}\text{l}\text{-rmphenylalanine}$ in a water-ethanol mixture. However, the first and second derivative spectra and various first derivative spectra were found to have 12 isoderivative points, and all the bands of the different spectra displayed the two-state character of the transition. The degree of transition was determined from the change in the peak height of each band and this coincided well with the pH-titration data.     

Anionic polymerization and properties of graft copolymers consisting of alternating styrene/maleimide copolymer main chains and polyamide 6 grafts

This article is focused on the synthesis of a new type of graft PA6, which contained alternating styrene/maleimide copolymer main chains and PA6 grafts, by anionic polymerization. The preprepared styrene/maleimide copolymers with acylated caprolactam (ACL) pendants were used as macroactivators for the polymerization of molten ε‐caprolactam (CL). Because of the low activating energy for the initial nucleophilic attack of CL anion on the N‐ACL, the polymerization took place in a few minutes. The macroactivators were characterized by ¹H‐NMR. And the thermal properties, dimensional stability, crystallinity, and solvent resistance ability of the graft PA6 were studied, using DSC, TGA, XRD, water absorption measurement, and solubility experiment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

丙烯腈/丙烯酸甲酯/衣康酸三元共聚物序列结构的Monte Carlo模拟

以丙烯腈(AN)、丙烯酸甲酯(MA)、衣康酸(IA)为共聚单体,合成碳纤维用聚丙烯腈原丝的三元共聚物,利用Monte Carlo法模拟了AN／MA／IA三元共聚物的组成和序列结构,讨论了共聚单体对共聚物分子链序列结构的影响,探讨了增加序列结构均匀性的方案。结果表明:Monte Carlo法可以较为准确的模拟该共聚物的序列结构;AN／MA／IA以98／0.7／1.3的单体配比可以得到序列结构比较理想的共聚物;采取分批加入IA的方法,使共聚物的序列结构均匀性得到提高。     

衣康酸/苯乙烯磺酸/丙烯酸共聚物阻垢剂的合成研究

以衣康酸(IA)、苯乙烯磺酸(SSA)和丙烯酸(AA)为单体,过硫酸铵为引发剂,异丙醇为链转移剂,在水相中合成了IA/SSA/AA共聚物阻垢剂.通过正交试验确立了最佳合成工艺条件:单体质量比m(IA):m(SSA):m(AA)=2:1:4,引发剂与总单体的质量比为4.5%,链转移剂与总单体质量比为9.5%,在95℃下反应2 h.当IA/SSA/AA共聚物的极限黏数为5.5～6.0 mL/g,实验水中Ca2 的质量浓度为1.6g/L,阻垢剂投加质量浓度为10 mg/L时,共聚物阻CaCO3垢的阻垢率高达91.9%,特别适用于高矿化度的工业循环冷却水和油田回注水.     

Soap-free emulsion polymerization of styrene using poly(methacrylic acid) macro-RAFT agent

A well-defined poly(methacrylic acid) (PMAA) macro-RAFT agent has been synthesized by the bulk polymerization using 4-toluic acid dithiobenzoate as a RAFT agent and successfully employed as a reactive emulsifier in the soap-free emulsion polymerization of styrene, leading to a formation of stable latex. The amphiphilic block copolymer, prepared from the in situ micelle formation, contains a hydrophilic PMAA block and a hydrophobic PS block, via styrene monomer transfer reaction to the dithioester function in PMAA macro-RAFT agent during the nucleation step. The chemical structure of the synthesized PS with the PMAA macro-RAFT agent was confirmed using FTIR and NMR. In addition, it was confirmed that the macro-RAFT agent is present on the particle surface via the ESCA measurement. The reaction mechanism was proposed that the stable spherical particles enlarged by the aggregation of small particles, which were also produced by the chemical or physical bonding between the tiny small particles. The results indicate that the PMAA macro-RAFT agent is used as emulsifier for the formation of PS particles and block copolymer [P(S-b-MAA)] in situ.     

Evaluation of compatibility of methacrylic copolymers by capillary viscometry

The estimation of the compatibility of different pairs of polymers can be based on capillary viscometry data for ternary polymer‐polymer‐solvent systems using mathematical models based on the slope of the Huggins equation (Δb) and Huggins constant (Δk′). In this study, the compatibility of binary mixtures of six types of methacrylic copolymers with similar molecular weights but different functional groups [one characterized by amine groups (EuE), two by ammonium groups (EuRL EuRS), two by carboxylic groups (EuL EuS), and one without charge (EuNE)] was evaluated using these methods. On the basis of Huggins and Kraemer constants, acetone and tetrahydrofurane were selected as good solvents for the programmed blends. Cationic copolymers mixed with anionic copolymers showed the formation of visible aggregates. The study performed on the other blends showed that EuRL and EuRS could be considered compatible with EuE; EuNE was incompatible with both EuL and EuE, EuL and EuS were incompatible between them. EuRL and EuRS could be considered compatible even if the weight ratio seems to influence the behavior of the two copolymers. The Δk′ approach seems to be more robust than the Δb model. The compatibility of different pairs of methacrylic copolymers with similar molecular weights could be evaluated using capillary viscometry. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1662–1668, 2000     

New perfectly difunctional organolithium initiators for block copolymer synthesis: 2. Difunctional polymers of dienes and of their triblocks copolymers with styrene

New organodilithium initiators were prepared in a hydrocarbon solvent in the absence of any polar additive. Although these initiators are insoluble when they are synthesized, they may be easily purified and reacted with dienes to give perfectly telechelic polydienes having unimodal distributions and low dispersity. A good agreement between experimental and theoretical molecular weights was observed. The polymer microstructures were similar to those of polymers initiated by butyllithium in the same solvent. Triblock thermoplastic elastomers were also prepared, the characteristics of which are given. The mechanical properties of a S.B.S. sample support also the claim of a good initiating ability and difunctionality of these initiators.     

Syntheses and characterization of starch-poly(methacrylic acid) graft copolymers

Methacrylic acid (MA) was graft polymerized onto starch using Ce⁴⁺ initiator in aqueous medium. The dependence of grafting on the reaction variables, such as monomer and initiator concentration and time and temperature, was studied in detail. Acid hydrolysis and infrared (IR) spectroscopy were used for the confirmation of graft copolymer formation. Further, a representative graft copolymer was characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The solubility/swellability and the gelatinization characteristics of the copolymers are also reported. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1399–1403, 1997     

Hydration mechanism on a poly(methacrylic acid) film studied by in situ attenuated total reflection infrared spectroscopy

A drastic structure change during a hydration process of a poly(methacrylic acid) (PMAA) film was observed by time-resolved in situ attenuated total reflection infrared (ATR-IR) spectroscopy. Inter- or intra-hydrogen-bonds via side-chain carboxyl groups are formed as cyclic dimers, side-on dimers and linear open chain oligomers including open dimers in a dried PMAA film. By contacting water, the side-chain hydrogen-bonds in PMAA are dissociated instantly, and then the subsequent carboxyl groups which have no hydrogen-bond newly hydrate with water molecules in a side-on form. Quantum chemical calculations (QCCs) using a model monomer of propionic acid (PA) also support the hydrogen-bonded and hydrated structures explored by the ATR-IR spectroscopy. It has been concluded from the present study that the dissociation of hydrogen-bonded and newly created hydrated structures via the carboxyl groups play an important role for the swelling of PMAA in water.     

甲基丙烯酸2,2,3,4,4,4 - 六氟丁酯的合成

本文采用一锅法的工艺通过甲基丙烯酸先酰化再与2,2,3,4,4,4-六氟丁醇酯化的方法制备了甲基丙烯酸2,2,3,4,4,4-六氟丁酯,并根据实验结果讨论了影响反应的主要因素。     

Toughening of polypropylene with styrene/ethylene‐butylene/styrene tri‐block copolymer: Effects of reactive and nonreactive compatibilization

The effects of compatibilization on the toughening of polypropylene (PP) by melt blending with styrene/ethylene‐butylene/styrene tri‐block copolymer (SEBS) in a twin‐screw extruder were investigated. The compatibilizers used were SEBS functionalized with maleic anhydride (SEBS‐g‐MA), PP functionalized with acrylic acid (PP‐g‐AA), and bifunctional compound p‐phenylenediamine (PPD). The effects of the compatibilization were evaluated through the mechanical properties as well as through the determination of the phase morphology of the blends by scanning electron microscopy. Reactive compatibilized blends show up to a 30‐fold increase in impact strength compared with neat PP; likely the result of the reaction of the bifunctional compound (PPD) with the acid acrylic and maleic anhydride groups, this increase in strength rendered both morphological and mechanical stability to these blends. The addition of PPD to the blends significantly changed their phase morphologies, leading to larger average diameters of the dispersed particles, probably as a result of the morphological stabilization at the initial processing steps during extrusion, with the occurrence of chemical reactions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3466–3479, 2002     

甲基丙烯酸接枝改性玉米芯对Cd2+的吸附及机理

以甲基丙烯酸为单体、高锰酸钾/浓硫酸为引发体系对玉米芯进行接枝改性,成功引入羧基官能团,结合扫描电镜、红外光谱和zeta电位等分析手段研究了吸附条件对玉米芯吸附Cd²⁺过程的影响及其吸附机理。结果表明,吸附过程符合Langmuir模型和准二级动力学方程,改性玉米芯对Cd²⁺的吸附主要是化学吸附过程,吸附速率是颗粒内扩散速率和膜扩散速率共同影响的结果;在pH 7、投加量为5 g·L^-1、温度为30℃、吸附时间为6 h的条件下,接枝改性玉米芯和原玉米芯对Cd²⁺的最大吸附容量分别为28.00 mg·g^-1和5.96 mg·g^-1,提高了近4倍;玉米芯对Cd²⁺的吸附是一个自发的吸热反应,温度越高,自发程度越大;接枝改性玉米芯对Cd²⁺的吸附过程中,参与反应的主要官能团有羧基、羟基、酰胺基和甲基等,吸附Cd²⁺后的接枝改性玉米芯表面出现褶皱和白色小颗粒,孔隙消失,电负性增大。     

Pd-Ba/Ce-Zr-La-Al2O3/堇青石催化剂对甲基丙烯酸尾气的催化燃烧

采用浸渍法制备Pd-Ba/Ce-Zr-La/堇青石催化剂,以甲基丙烯酸尾气为模型,考察Ba的引入对Pd催化剂催化燃烧活性的影响。并用XRD、BET、SEM和TPD等对催化剂进行了表征。研究表明,Ba的引入提高了催化剂的催化活性和热稳定性,经500 ℃焙烧的Pd-Ba/Ce-Zr-La/堇青石催化剂（Pd和Ba质量比为1∶7.5）具有很好的催化活性,起燃温度为130 ℃,完全燃烧温度仅为153 ℃,经1 000 ℃焙烧后,催化剂仍保持较高催化活性。     

Emulsifier‐free emulsion copolymerization of styrene with methacrylic acid

The study on batch emulsifier‐free emulsion copolymerization of styrene with methacrylic acid was conducted. The copolymerization process was followed by gravimetry, infrared, and transmission electron microscopy. The copolymerization mechanism differs from that of styrene with acrylic acid. The effect of solid content on particle size was examined, and it was found that the particle size was increased as the solid content was increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1747–1751, 2003