THE EFFECTS OF MIXED MICELLES OF SURFACTANTS ON POLYMERIZATION OF ACRYLAMIDE

The polymerization of acrylamide in mixed micellar solutions of surfactants, initiated by NaHSO₃ has been studied at 20 and 3Q° C with time variable method of thermokinetics for 1. 5-order reaction. The results indicate that the mixed micellar systems of cationic or anionic with zwitterionic surfactants (SLS/ CTAB, SLS/ TTAB, SLS/ SDS) and cationic with nonionic surfactants (Brij 357sol; CTAB, Bri-J35/TTAB, Brij35/ DTAB) have catalytic effect on the polymerization in the order, at 20° C. SLS/ SDS SLS/ TTAB SLS/ CTAB Brij35/ CTAB at 30° C SLS/ SDS SLS/ TTAB≈ / CTAB Bri-j35/ DTAB= sBrij35/ TTAB as Brij35/ CTAB, while Brij35/ SDS mixed micellar system has inhibition. These effects are attributed to the effect of the Stern layer of mixed micelles on the step of initiator (HSOT) to form free radical.     

THE EFFECT OF SLNGLE AND MIXED MICELLES OF SURFACTANTS ON POLYMERIZATION OF ACRYLAMIDE

Acrylamide is conveniendy polymerized in aqueous solution lo a water soluble polymer. The measurements of kinetic parameters of polymerization of acrylamide, in aqueous and micellar solution, have been earned out by conduction calorimeter. The polymerization is initiated by sodium sulfite and sulfite-persulfate redox system. The effect of initiator and monomer concentration as well as temperature and surfactants on polymerization rale constant has been investigated. The analog thermogram method has been employed to calculate the rate constants. The activation energy is calculated from Arrhenius relationship and molecular weights are determined by viscometry. Rate equations have been derived and reaction mechanism hove been suggested. The rate of reaction is found to increase with temperature and monomer concentration.     

STUDIES ON THERMOKINETICS(XVI) THE KINETICS OF THE POLYMERIZATION OF ACRYLAMIDE IN MICELLAR SOLUTION

The kinetics of the polymerization of acrylamide in aqueous solution and CTAB micellar solution initiated by sodium sulfite has been investigated with the theory and method of thermokinetics for n order reactions with equal concentration in this paper. The influence of initiator and CTAB concetrations on molecular weight of polyacrylamide has been discussed.The second—order rate constants of this reaction at 30 and 40°C in aqueous solution are 0. 112and 0. 0262dm³ mol^-1s^_1, respectively. The activation energy,based on measurements at these two temperatures,is 66. -4kJ mol^-1. The ratio k2√n in CTAB micellar solution is smaller than that in aqueous solution. The rate of forming radical in micellar solution has been decreased.     

THE EFFECT OF MIXED MICELLES OF SURFACTANTS ON THE ALKALINE HYDROLYSIS OF ESTERS

The alkaline hydrolysis of aromatic and normal aliphatic acid esters have been studied at 25°C In mixed micellar solution of surfactants (Brij35—SDS, Brij35 — DTAB, Brij35—TTAB.Brij35-CTAB. Triton X—100 —CTAB, Triton X— 100 —SDS) with UV spectrophotometry and the method of thermokinetics The critical mice liar concentrations of the corresponding systems have also been measured with UV spectrophotometry in this paper. K_jnln micellar pseudo-phase has been calculated- The ratios of ki.to ki.for all mixed micellar systems Investigated are less than 1. The results indicate that these reactions are inhibited by the mixed micelles and the mixed micelles exhibit a greater effect of Inhibition on the reactions than those do In corresponding single ones. The reason for this is that the micropolarity of the compact Stern layer of mixed micelle is lower, and the micro viscidity Is higher. The Inhibition effect! also depend on the hydrophobic chain length of the surfactants and the hydrophobicity of the substrate.     

无机盐对正负表面活性剂混合体系性质的影响

用滴体积法测定了四种离子强度下(μ=0.02, 0.05, 0.1, 0.2 mol·kg~(-1), 支持电解质为NaBr)C_(12)H_(25)SO_4Na/C_6H_(13)(NC_5H_5)Br混合体系在五种比例(10:1, 3:1, 1:1, 1:3, 1:10)时的临界胶团活度cma(25 ℃). 提出了无机盐对正负表面活性剂混合体系临界胶团活度的影响程度的计算式.     

THE EFFECT OF SURFACTANT MICELLES ON THE ALKALINE HYDROLYSIS OF DIMETHYLFORMAMIDE

The alkaline hydrolysis of dimethylformamide has been studied at 40'C in micellar solutions of single surfactant (CTAB. SDS. Brij 35) with the analog thermoanalytical curve method of thermokinetics. A kinetic equation of micellar catalysis under the condition of highter reactant concentration than micellar concentration ([S]>[M]) has been derived from the pseudophase model of micellar catalysis and some relative assumptions, The kinetic parameters. k_m, k_2mand the association constant of reactant with micelle K₁, have been calculated in this way. the results indicate that these surfactant micelles exhibit catalytic effect on the reaction. This is attributed to the micropolarity and local concentration effect of micelles.     

高浓度区正负离子表面活性剂混合胶团的形状与大小变化

本文研究高浓度区正、负离子表面活性混合胶团的形态及大小随浓度的变化规律。根据正、负离子表面活性剂混合体系的相行为,胶团溶液的光散射以及流变性质测量,提出了混合胶团的棒-球转变模型。认为在较高浓度,随浓度增大,混合胶团经历了一个长棒变短,短棒变为球状的转变过程。     

THE POLYMERIZATION THERMOKINETICS OF PYRROLE IN THE PRESENCE OF IRON TRICHLORIDE

The polymerization thermokinetics of pyrrole in the presence of iron trichloride art studied by using a Calvet microcalorimoter. The apparent activation energy, the pre-exponential constant and reaction order of this reaction in the temperature range of 25.2—37℃are 34.5 KJ·mol~(-1), 10~(2.74)S~(-1) and 1 respectively. The activation free-energies of this reaction at 25.2°, 30°and 37℃are 91.8, 92.9 and 94.2 KJ·mol~(-1) respectively.     

聚乙烯醇对丙烯酰胺聚合行为的影响

<正> 聚乙烯醇(PVA)在烯类单体自由基聚合反应中作为分散剂使用已有很长历史,对于PVA在不同催化体系中与烯类单体接枝聚合的研究报道也不少,其中有人报道PVA对过硫酸盐的分解具有促进作用,并可导致甲基丙烯酸甲酯在PVA大分子上接枝;也有人报道了PVA与过硫酸铵在水溶液中的相互作用,本文研究了在低浓度过     

对苯乙烯磺酸钠聚合动力学及与丙烯酰胺共聚合的研究

采用膨胀计法研究了对苯乙烯磺酸钠(SSS)在水溶液中聚合动力学,确定了聚合速率方程,测定了聚合表观活化能,并研究了对苯乙烯磺酸钠与丙烯酰胺(AM )在水溶液中共聚合的动力学行为,利用聚电解质———共聚物P(SSS -co -AM)与阳离子表面活性剂N ,N ,N- 三甲基十六烷基溴化铵(CTAB)的复合作用,采用电导滴定法测定了共聚物的组成,从而测得了对苯乙烯磺酸钠与丙烯酰胺的竞聚率.研究结果表明,对苯乙烯磺酸钠聚合速率方程为RP =K[M]1 .0 [I]0 .53,说明链终止为双基终止方式,引发过程与单体浓度无关;聚合表观活化能为84 . 96kJ·mol- 1 ;采用Kelen Tudos方法,求得对苯乙烯磺酸钠(SSS)和丙烯酰胺(AM)两单体的竞聚率分别为rSSS =0 . 2 7,rAM =2 . 2 1;采用Alfrey Price经验规则估算了单体苯乙烯磺酸钠的Q、e值为QSSS=0 .2 2 ,eSSS=0 .4 6 .     

在丙烯酰胺聚合反应中聚苯乙烯磺酸效应的研究

<正> 在聚合体系中添加具有一定结构的高分子化合物作模板,并利用此模板高分子与单体分子间存在的某种相互作用使单体分子按一定的排列进行聚合,这是所谓“模板聚合”的最初尝试,近年来,模板聚合已成为一类新的聚合方法,利用模板大分子对其周围单体分子反应过程和生成物结构、分子量的影响,有些研究者已由此成功地实现了对新生成物分子量和空间构型的控制,从而为实现高分子设计开创了新的途径。     

EFFECT OF POLYMERIZATION CONDITIONS ON THE LADDERLIKE STRUCTURE OF POLYPHENYLSILSESQUIOXANE

The ladderlike structure of PPSQ synthesized by using four kinds of catalysts (MgF_2,LiF, KOH and DCC) at different polymerization conditions has been investigated by IRand NMR. In the system using MgF_2 as the main catalyst, the most important factorwhich affects the ladderlike structure of PPSQ is the composition of the dual catalysts,MgF_2 and DCC. PPSQ prepared by using KOH as the catalyst has the highest regularityof ladderlike structure among all samples. PPSQ with different degree of ladder regularitycan be obtained by choice of polymerization conditions.     

在丙烯酰胺聚合反应中聚苯乙烯磺酸的大分子效应

本文研究了聚苯乙烯磺酸对丙烯酰胺聚合反应的影响。采用红外光谱、元素分析和电子能谱等手段研究了聚苯乙烯磺酸同丙烯酰胺分子间的相互作用。发现二者间存在着由磺酸基与酰胺基相互作用而形成的铵盐的结合形式,从而提出了在聚苯乙烯磺酸存在下丙烯酰胺聚合历程的模式,并以此机理解释了聚苯乙烯磺酸在丙烯酰胺聚合反应中的作用。     

受阻胺对甲基丙烯酸甲酯聚合的影响

本文研究了受阻胺TMP、TMPM、TUV-770对MMA、St本体聚合的影响。无论用BPO或AlBN引发MMA聚合时,TMPM或TUV-770都能延长诱导期,但对R_p的影响较小,而TMP能使R_p略增。测定了聚合反应的表观活化能和动力学方程。     

羧化聚丙烯载体的链结构对丙烯腈聚合的影响

研究了羧化聚丙烯载体(不饱和羧酸接枝聚丙烯)接枝链的结构对丙烯腈聚合速度的影响。在引发活性方面对聚羧酸氧钒(聚合物负载催化剂)、异丁酸氧钒(小分子同系物)和硫酸氧钒(小分子非同系物)作了对比。实验结果表明:(1)(P-COO)_2VO两羧基之间存在着协同作用;(2)大分子链效应加强了羧基的协同作用;(3)聚羧酸链的d-、1-构型、羧基间距和载体的传质效应对聚合速度均有影响;(4)在本实验条件下,引发机理与高分子载体的链结构无关。     

EFFECT OF POLYMERIZATION CONDITIONS ON THE MOLECULAR WEIGHT OF POLYPHENYLSILSISQUIOXANE

Samples of polyphenylsilsisquioxane (PPSQ)using CaF_2 or MgF_2 as the main catalysts hadbeen prepared under different polymerization conditions. The results were treated on anorthogonal design L_9 (3~4). All weight-average molecular weights (M_W ) of PPSQ had beenmeasured by gel permeation chromatography (GPC). Effects of polymerization conditionsincluding reaction temperature, composition of the dual catalysts (CaF_2 or MgF_2 and DCC),mixture of solvents and reaction time on M_W of PPSQ have been discussed. The quantity of thecatalysts is the most important factor that affects M_W of PPSQ. Reaction temperature is thesecond important factor. Appropriate polymerization condition has been established to get PPSQwith high M_W.     

聚合物载体-稀土金属络合物的研究 Ⅵ.聚合物载体-钕络合物对丁二烯聚合的催化活性

红外光谱研究表明,苯乙烯-丙烯酸共聚物载体-钕络合物具有双配位的羧酸根结构,Nd-O键富有共价性。考察了载体钕络合物催化丁二烯聚合的一般规律,载体钕络合物的组成与聚合活性的关系。在溶剂THF或二氧六环的存在下制得的苯乙烯-丙烯酸共聚物最适宜于合成高活性的载体钕络合物。功能团-COOH含量大约12％,金属钕含量与功能团含量摩尔比在0.20左右的载体钕络合物催化活性最佳。     

β环糊精对苯乙烯无皂乳液聚合的影响

以苯乙烯为单体,过硫酸钾为引发剂,研究了β环糊精对无皂乳液聚合反应的影响.结果表明,环糊精的引入可以大大加快反应速度,提高单体转化率,并且反应速度随环糊精加入量的增加而增大;同时,环糊精的引入能够减小制得的聚合物微球的粒度分布,使聚合物微球的粒径大小更加均匀,而对粒径的影响不是很大.动力学分析的结果表明,环糊精可以提高单体的反应活性.当环糊精/单体比例增大到0.2时,单体反应活性是空白体系的3.3倍.     

烷基铝对球形MgCl_2负载的茂金属催化剂催化乙烯聚合的影响

以甲基铝氧烷(MAO)为助催化剂的茂金属催化剂虽然具有催化活性高、分子量分布窄、聚合物化学组成均匀等优点,但其极高的Al/Zr比和聚合物颗粒形态差等缺点限制了其工业化应用,因此对茂金属催化剂的负载化成为近年来的研究热点.在众多的载体中,球形MgCl2是研究得很少的一类载体,文献中曾采用先负载主催化剂茂金属配合物,聚合时再加入助催化剂MAO的方法[1],由于加入的MAO与主催化剂的络合能力很强,会使部分载上的主催化剂溶解下来,成为均相聚合[2,3],导致聚合物颗粒形态差,且粘釜现象严重.我们则采用相反的思路,即先将助催化剂MAO负载在球形MgCl2上,制得MgCl2/MAO,在聚合前再将MgCl2/MAO与Et[Ind]2ZrCl2混合陈化,并立即在少量烷基铝活化下引发乙烯聚合[4],实验结果表明,该催化剂聚合活性高、聚合物的颗粒形态好、且不粘釜,是一种新型的载体催化剂.由于烷基铝的加入可使催化剂的活性大幅度提高,所以本文将烷基铝也称作助催化剂,来研究其对该载体催化剂催化乙烯聚合的影响.