少量甲苯存在下2,6-二甲基苯酚在水介质中的氧化聚合

研究了甲苯对水介质中合成的聚2,6-二甲基-1,4-苯醚(PPO)分子量及聚合物粒子形态的影响.研究发现,2,6-二甲基苯酚(DMP)氧化聚合过程中引入一定量甲苯后,可显著提高PPO的分子量.采用差示扫描量热仪测定了PPO/甲苯混合物的玻璃化温度,发现PPO/甲苯混合物的玻璃化温度随甲苯用量的增加而降低,其与甲苯用量的关系符合Fox方程.关联了PPO分子量与PPO/甲苯混合物的玻璃化温度的关系,结果显示玻璃化温度对PPO分子量起重要作用,这可能是由于在搅拌作用下甲苯能够溶胀聚合物粒子,降低其玻璃化温度,导致预聚物分子链的活动性增加,促进预聚物的后氧化聚合.采用透射电镜研究了水介质中合成的聚合物粒子形态,发现加入甲苯后聚合物最终粒子呈紧密的鹅卵石形,甲苯使初级粒子融合在一起,初级粒子的轮廓模糊甚至消失.     

水介质中铁氰化钾作用下2,6-二甲基苯酚氧化聚合初始动力学

采用电化学方法研究了水介质中铁氰化钾作用下2,6-二甲基苯酚(DMP)氧化聚合初始动力学,确定了各反应参数对DMP氧化聚合的影响。发现DMP聚合初始速率随DMP和铁氰化钾浓度的增加而增加,DMP聚合初始速率与DMP浓度的一次方呈正比,与铁氰化钾浓度的二次方呈正比。DMP聚合初始速率随NaOH浓度的增加而增加,这是因为DMP的氧化电位随NaOH浓度的增加而降低,DMP聚合初始速率与NaOH浓度的二次方呈正比。DMP聚合初始速率随温度的升高而增加,根据初始速率求出了不同温度下DMP聚合初始速率常数,并由Arrhenius方程求得DMP氧化聚合的表观活化能为47.7kJ·mol-1。最后根据Arrhenius方程和聚合初始速率与反应物浓度的关系建立了DMP聚合初始动力学模型,并验证了模型的正确性。     

聚乙烯基咪唑对2,6-二甲基苯酚氧化聚合中底物的浓缩效应

制备了铜-聚乙烯基咪唑(Cu(Ⅱ)-PVI)络合物,用于催化水介质中2,6-二甲基苯酚(DMP)的氧化聚合,与传统催化剂Cu(Ⅱ)-EDTA络合物相比,其催化效率约提高十倍。为探究Cu(Ⅱ)-PVI络合物催化效率提高的原因,采用N,N’-亚甲撑-二(丙烯酰胺)作为交联剂与N-乙烯基咪唑共聚合制备了PVI水凝胶。采用紫外可见吸收光谱研究了PVI水凝胶对DMP的吸附量随时间的变化,发现水溶液中DMP的浓度先随时间延长而降低,而PVI水凝胶中DMP的浓度则随时间延长而增加,最后达到平衡,说明PVI对反应底物DMP有浓缩效应。认为Cu(Ⅱ)-PVI络合物催化水介质中DMP氧化聚合反应时,其催化效率的提高归结为PVI微团对催化剂和反应底物的浓缩效应。     

基于HPCMS的功能性星型多臂共聚物的制备及应用

4-氯甲基苯乙烯(CMS)分子同时含有双键和卤原子,可通过自引发原子转移自由基聚合(ATRP)制备准三维球状超支化聚4-氯甲基苯乙烯(HPCMS)。HPCMS分子内带有大量苯亚甲基氯和苯次甲基氯基团,可继续作为引发剂,在HPCMS表面接枝聚合物链段,制得星型多臂共聚物。通过改变接枝链段的结构,可以得到一系列具有特殊结构和性能的共聚物。详细介绍了HPCMS的合成及支化度的测量,着重综述了星型多臂共聚物的合成及其在无机纳米粒子表面修饰、固体电解质、药物运载体等方面的应用进展,同时展望了星型多臂聚合物在热塑性弹性体方面的应用。     

2,6-二[4-′(N,N-二苯基氨基)芪]苯并[1-2,4-5]二噁唑的合成与发光特性

通过对二苯氨基苯甲醛与2,6-二(4-氯甲基苯基)苯并[1-2,4-5]二唑之间的Wittig-Horner反应,设计并合成了一个2,6-二[4-′(N,N-二苯基氨基)芪]苯并[1-2,4-5]二唑新化合物,目的在于均二苯乙烯分子中同时引入空穴传输和电子传输结构单元,可望提高均二苯乙烯型发光材料的发光强度和光量子效率.采用UV-VisI、R1、HNMR和元素分析等分析方法对合成产物结构进行了确认,并考察了溶剂对其光致发光特性的影响.所合成化合物的相关分析数据表明:1)其分子中的两个均二苯乙烯基均为反式“芪”结构特征;2)随溶剂极性增高,其UV-Vis光谱和荧光光谱的λmax红移;3)可用作蓝色发光材料.     

2,6-二[4＇-（N,N-二苯基氨基）芪] 苯并[1-2,4-5]二唑的合成与发光特性

通过对二苯氨基苯甲醛与2,6-二（4-氯甲基苯基）苯并[1-2,4-5]二（口恶）唑之间的Wittig-Horner反应,设计并合成了一个2,6-二[4＇-（N,N-二苯基氨基）芪]苯并[1-2,4-5]二（口恶）唑新化合物,目的在于均二苯乙烯分子中同时引入空穴传输和电子传输结构单元,可望提高均二苯乙烯型发光材料的发光强度和光量子效率.采用UV-Vis、IR、1HNMR和元素分析等分析方法对合成产物结构进行了确认,并考察了溶剂对其光致发光特性的影响.所合成化合物的相关分析数据表明：1）其分子中的两个均二苯乙烯基均为反式＂芪＂结构特征;2）随溶剂极性增高,其UV-Vis光谱和荧光光谱的λmax红移;3）可用作蓝色发光材料.     

α一甲基苯乙烯的均聚和共聚及应用研究进展

介绍了α-甲基苯乙烯在本体、溶液、乳液聚合等方面的均聚和共聚合研究进展;对α-甲基苯乙烯聚合物的结构特性、热力学性能进行了总结;列举了α-甲基苯乙烯在有机合成及高分子助剂等方面的应用;并对此领域的发展进行了展望.     

苯酚焦油中提取α-甲基苯乙烯二聚物新工艺

苯酚焦油是异丙苯法生产苯酚丙酮装置的副产物,其中含有的苯酚、α-甲基苯乙烯二聚物等均为高附加值的产品。采用先初馏后结晶再减压精馏新工艺从苯酚焦油中提取出α-甲基苯乙烯二聚物产品。研究结果表明,进料量为0.5～1 mL/min、操作压力为(0.005～0.01)MPa、回流比为3∶1～4∶1,α-甲基苯乙烯二聚物产品的收率达到80.28%,α-甲基苯乙烯二聚物产品的纯度达到99.17%。工艺路线简单,有效回收了苯酚焦油中的α-甲基苯乙烯二聚物,实现了清洁生产。     

2-甲基-4-氨基-6-硝基间苯二酚盐酸盐的合成研究

研究了通过用2-甲基-4,6-二硝基间苯二酚(2-MDNR)选择性还原法制备聚对苯撑甲基苯并二噁唑(MPBO)AB型单体的关键中间体2-甲基-4-氨基-6-硝基间苯二酚盐酸盐(2-MANR.HCl)的合成新技术。以2-甲基间苯二酚(2-MR)为原料、初步探索工艺条件基础上,采用二次回归正交组合设计试验及方差分析,建立了2-MDNR收率y与各影响因素xi的数学模型,得到各影响因素较优取值,同时确定制备2-MANR.HCl的工艺及精制条件。结果表明,采用二次回归正交试验建立回归方程得到的较佳工艺条件和确定的选择还原工艺,可先后分别制得收率为92.15%,高效液相色谱(HPLC)纯度为99.92%的2-MDNR和收率为73.71%,HPLC纯度为98.71%的2-MANR.HCl产品。2-MDNR和2-MANR.HCl结构经IR,NMR,MS定性和表征,其中化合物2-MANR·HCl为一种新化合物。     

α-甲基苯乙烯的均聚和共聚及应用研究进展

介绍了α-甲基苯乙烯在本体、溶液、乳液聚合等方面的均聚和共聚合研究进展；对α-甲基苯乙烯聚合物的结构特性、热力学性能进行了总结；列举了α-甲基苯乙烯在有机合成及高分子助剂等方面的应用；并对此领域的发展进行了展望。     

Mechanism of the particle formation during the oxidative polymerization of 2,6‐dimethylphenol in an aqueous medium

The changes of the molecular weight and particle size with time during the oxidative polymerization of 2,6‐dimethylphenol in an aqueous medium were studied. At the beginning of the oxidative polymerization, the oligomers with the hydrophilic phenoxy anion at the end of oligomer chains are formed rapidly in the aqueous medium. When the molecular weight of the oligomer reaches up to a critical value, the oligomer precipitates out from the water, resulting in the formation of the original particle (or domain). With the increase of the molecular weight, the concentration of the phenoxy anion and the surface charge density of the original particles decrease; therefore, the repulsion force between original particles weaken and the stability of particles in water decreases, resulting in the coagulation of the original particle and the formation of the primary particle. With the further progression of the polymerization, the primary particles coagulate and final particles are formed. A three‐stage mechanism of the particle formation is proposed, that is, the particle nucleation, first coagulation, and second coagulation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3649–3653, 2007     

Synthesis of poly(2,6-dimethyl-1,4-phenylene ether) with controlled molecular weight via suspension polymerization catalyzed by amine–copper (I) complexes under various reaction conditions

The oxidative suspension polymerization of 2,6-dimethyl phenol (DMP) to poly(2,6-dimethyl-1,4-phenylene ether) (PPE) was performed with the use of emulsifier in water–chloroform biphasic medium. The effects of DMP/catalyst mole ratio, ligands, emulsifiers, and 2,4,6-trimethyl phenol on polymerization were investigated in terms of molecular weight and yield. Various ligands were employed in the polymerization to investigate ligand efficiency. Intrinsic viscosity measurement data showed that the most efficient ligand was 1-methyl imidazole (Meim) in terms of molecular weight. By incorporating different amount of DMP in the monomer feed, it was possible to control the molecular weight of PPE in the oxidative suspension polymerization.     

Aerobic oxidative polymerization of 2,6‐dimethylphenol in water with a highly efficient copper(II)– poly(N‐vinylimidazole) complex catalyst

A Cu(II)–poly(N‐vinylimidazole) (PVI) complex was prepared and used to catalyze the oxidative polymerization of 2,6‐dimethylphenol (DMP) to form poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) in water. The stoichiometric ratio between imidazole groups in PVI and copper ions was found to be 4 when continuous variation analysis was applied. Compared with a conventional Cu(II)–low‐molecular‐weight ligand complex, a high catalytic efficiency was observed in the polymerization of DMP catalyzed by the Cu(II)–PVI complex. The influence of the Cu(II)–PVI complex concentration and imidazole/Cu(II) molar ratio on the oxidative polymerization of DMP was studied. Both the yield and molecular weight of PPO increased significantly with the catalyst concentration and decreased with the imidazole/Cu(II) molar ratio. The molecular weight of PVI also played an important role in the improvement of the catalytic efficiency. The high catalytic efficiency of the Cu(II)–PVI complex may have been due to the concentration effect of the catalyst and substrate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of swelling agent on the molecular weight of poly(2,6‐dimethyl‐1,4‐phenylene oxide) synthesized in an aqueous medium

The effects of the species and content of a swelling agent on the molecular weight of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) synthesized in an aqueous medium were studied. It was found that the molecular weight of PPO increases after introducing a certain amount of the swelling agent during the oxidative polymerization of 2,6‐dimethylphenol (DMP). T_g of the PPO/swelling agent mixture decreases with the increase of the swelling agent content, and the relation between T_g of the PPO/swelling agent mixture and the swelling agent content obeys Fox equation. After the introduction of the swelling agent during the oxidative polymerization of DMP, the molecular weight of PPO is correlated with T_g of the PPO/swelling agent mixture and it was revealed that T_g plays an important role in the molecular weight of PPO synthesized in the aqueous medium. The same molecular weight of PPO can be obtained only if T_g of the PPO/swelling agent mixture is the same, no matter what kind of swelling agent is introduced during the oxidative polymerization of DMP. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

The Effect of Initiators on the Emulsion Polymerization of 2-hydroxyethyl Methacrylate

The emulsion polymerization of 2-hydroxyethyl methacrylate (HEMA) was conducted at 80^○C, using a series of initiators and using either sodium dodecyl sulfate (SDS) or a mixture of SDS and poly(vinyl pyrrolidone) (PVP) as the emulsifier. For the series of initiators (including 2,2'-azobisisbutyronitrile (AIBN), 2,2'-azobis-(2-amidinopropane) dihydrochloride (AAP), 4,4'-azobis(4-cyanopentanoic acid) (ACPA) and 1,1'-azobis(cyclohexane carbonitrile) (ACHC)), the aqueous (aq.) solubility sequence correlates well to the polymerization rate sequence, while the sequence of initiation coefficient correlates poorly to the polymerization rate sequence. There is significant aq. phase polymerization, and frequent particle nucleation and coagulation during the polymerization. Increasing the monomer/water ratio, the polymerization rate does not increase proportionally to the particle number. It is suggested that the dominant locus for the formation of radicals is in the oil phase, and single radicals are formed by desorption of counterpart radicals from the particles. This revised version was published online in July 2006 with corrections to the Cover Date.     

纳米SiO_2改性水性聚氨酯乳液的制备及性能研究

以硅烷偶联剂(KH-550)作为纳米二氧化硅(nano-SiO2)的表面处理剂,以甲苯二异氰酸酯(TDI)、聚醚二元醇(N-220)、二羟甲基丙酸(DMPA)和nano-SiO2等为主要原料,制备nano-SiO2改性WPU(水性聚氨酯)乳液。着重探讨了DMPA的加料方式、DMPA和nano-SiO2用量等对WPU乳液稳定性、粒径分布、耐水性和力学性能等影响。结果表明:采用先加入DMPA后扩链的加料方式,可制得外观及稳定性均较好的WPU乳液;当w(DMPA)=5%、w(改性nano-SiO2)=2.0%时,WPU乳液及其胶膜的综合性能较好。     

Dispersion polymerization of styrene in aqueous alcohol solution: Effects of reaction parameters on the polymer particle formation

Dispersion polymerization of styrene in an aqueous alcohol solution using poly(2-ethyl-2-oxazoline) as a polymeric stabilizer was performed to prepare micron-size monodisperse polystyrene particles. As the water content of the solvent increased, the polymerization rate and the molecular weight of the polymer particles increased and the particle size decreased. Effects of concentrations of stabilizer and initiator upon the polymerization and the size of the resulting polystyrene particles have been examined in the solvent containing different water contents.     

Synthesis of poly(2,6-dimethyl-1,4-phenylene oxide) derivatives in water using water-soluble copper complex catalyst with natural ligands

Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) was synthesized by oxidative polymerization of 2,6-dimethylphenol (DMP) using a water-soluble copper complex catalyst under oxygen and with natural ligands in alkaline water. Arginine, guanine, adenine, cytosine, histidine, and folic acid were used as ligands for the copper complex. Arginine performed the best, with a yield of 72%, a number-average molecular weight (M_n) of 4400, and a molecular weight distribution (M_w/M_n) of 1.7. It was then used to optimize reaction conditions. Surfactants, temperature, and sodium hydroxide concentration were varied in copolymerization of DMP and 2-allyl-6-methylphenol (AMP) to produce allyl-containing PPO with 77% yield (M_n = 4500; M_w/M_n = 1.8). The optimum conditions were applied to copolymerization of DMP, AMP, and bisphenol A, leading to dihydroxyl PPO analogs containing thermally cross-linkable allyl groups. The thermal properties of these thermosetting PPOs were studied by differential scanning calorimetry, thermogravimetric analysis, and Fourier-transform infrared spectroscopy.     

The Mechanism of Copper(II)-catalysed Polymerization of 2,4,6-Tribromophenols

The copper(II )-catalysed polymerization of 2,4,6-tribromophenol and 2,4,6-tribromo-3-methylphenol by homogeneous and heterogeneous reaction was studied. The dependence of polymer yield and molecular weight on reaction time was investigated. The variance of bromide ion concentration in the polymerization mixture was measured continuously by a bromide ion selective electrode. The existence of phenoxy radical during the homogeneous polymerization process was confirmed by electron spin resonance measurements. A quinol ether equilibrium polymerization mechanism was proposed for the copper(II)-catalysed homogeneous polymerization of 2,4,6-tribromophenols. © of SCI.