丙烯酰胺在聚乙二醇水溶液中的聚合动力学

用改进溴法对丙烯酰胺 (AM)在聚乙二醇 (PEG)水溶液中聚合动力学进行研究 .在单一和氧化还原引发体系中分别考察了引发剂、单体和PEG用量、不同HLB值乳化剂以及聚合温度等因素对动力学的影响 .得到AM聚合速率与过硫酸铵 (APS)浓度的 0 91次方成正比 ;单一APS和APS 三乙醇胺 (TEA)氧化还原引发体系中的AM聚合表观活化能分别为 96 1和 4 2 3kJ mol.     

聚烯丙基氯化铵模板存在下丙烯酰胺-丙烯酸共聚合反应动力学研究

丙烯酰胺 (AM)和丙烯酸 (AA)模板共聚合是以聚烯丙基氯化铵 (PAAC)模板存在下 ,在水溶液中进行 ,在这体系中 ,模板PAAC和单体AA有很强的相互作用 ,而单体AM与模板则没有作用 .应用膨胀计和电导滴定方法研究了影响聚合反应速度的各种因素 ,得到的结果指出 ,在聚烯丙基铵模板作用下共聚合反应遵循Ⅰ型 (zip)模板聚合反应机制 ,速度最高值出现在模板单元T与单体AA等摩尔比 (T AA =1)处 ,这表明在反应溶液中PAAC和单体AA具有很强的相互作用 .测得它们的竞聚率分别为r1 =2 6 8(AA)和r2 =0 4 4 (AM) ,与没有模板存在时相比 ,大幅度增高的r1 值表明此共聚合反应 ,生成AA长序列结构的可能性大大增加 .同时发现聚合反应速度分别和单体浓度及引发剂浓度的 1 1和 0 83次方成正比 ,由于模板的作用数值高于常规值 .     

以PAAS为模板AM与DMC的模板共聚合反应

在水溶液中以聚丙烯酸钠(PAAS)为模板,进行了丙烯酰胺(AM)与2-甲基丙烯酰氧乙基三甲基氯化铵(DMC)的共聚合反应。研究了其聚合动力学,并对模板共聚物的序列结构进行了表征,最后对其进行了絮凝性能评价。结果表明:聚合反应符合模板聚合Ⅰ型机理,聚合反应速率分别与单体浓度和引发剂浓度的1.63和1.64次方成正比,此种共聚物与无模板参与聚合的普通共聚物相比具有更长的DMC序列长度,对高岭土悬浮液的絮凝沉降速率优于普通共聚物。     

对甲氧基苯辛基二甲基烯丙基氯化铵与丙烯酰胺共聚动力学研究

采用定时取样研究了以过硫酸钾-亚硫酸氢钠为引发剂,对甲氧基苯辛基二甲基烯丙基氯化铵(ADMAAC)和丙烯酰胺(AM)在水溶液中的共聚反应动力学,测定了相应的聚合速率方程、聚合表观活化能;采用阴阳离子相互作用测定残余ADMAAC的含量,紫外分光光度法测定残余AM的含量,根据单体投料量和残余量差值,得到低转化率下共聚物的组成,按Kelem-Tudos法得到两单体竞聚率。实验结果表明:聚合反应温度在40℃下,聚合速率方程为:Rp=K[M]1.241[KPS]0.52[SHS]0.55;根据Arrhenius经验公式计算出对甲氧基苯辛基二甲基烯丙基氯化铵(ADMAAC)和丙烯酰胺(AM)共聚的表观活化能为73.85kJ/mol,高于AM水溶液均聚合的活化能Ea(70.32kJ/mol);两种单体的竞聚率为rADMAAC=0.197、rAM=4.503,为ADMAAC-AM共聚合反应控制确定了重要的动力学参数。两单体的竞聚率的积小于1,ADMAAC与AM共聚合行为类型是一种无恒比点的非理想共聚行为,共聚物组成曲线,在对角线下方。     

微波辐照下丙烯酰胺的原子转移自由基共聚合

在微波辐射下,以水为反应介质,2-氯丙酰胺为引发剂,氯化亚铜/2,2′-联吡啶为催化体系,自制的磺基甜菜碱两性离子功能单体3-(2-甲基丙烯酰氧乙基二甲胺基)丙磺酸盐(DMAPS)与丙烯酰胺(AM)单体进行原子转移自由基共聚合反应,得到磺基甜菜碱型两性离子聚合物P(AM-DMAPS)。 讨论了微波功率、反应时间、单体用量、引发剂用量、催化剂和配体用量等因素对聚合反应的影响,并与相应的热聚合法进行了对照。 结果表明,微波辐射功率240 W,反应时间为1250 s时,微波辐射下共聚合的表观速率常数(Kappp)为热聚合法4.5倍,此时AM与DMAPS在水介质中的最佳合成条件为:单体总浓度4 mol/L(其中功能性单体DMAPS在混合单体中所占摩尔分数为1.0%),引发剂浓度0.015 mol/L,催化剂浓度0.01 mol/L。 此时转化率为40.15%,Mn为46410。     

VAC与甲基丙烯酰氧乙基三甲基氯化铵无皂乳液共聚合动力学研究

研究了醋酸乙烯酯 (VAC)与甲基丙烯酰氧乙基三甲基氯化铵 (DMC)无皂乳液共聚合动力学 ,考察了引发剂偶氮二异丁基脒盐酸盐 (AIBI)浓度、单体浓度、温度等因素对聚合反应速率的影响 ,得到单体总浓度和引发剂浓度影响反应速率的动力学方程为 :Rp=k1 [M]0 6 3[AIBA]1 0 ;各单体浓度影响反应速率的动力学方程为 :Rp=k2 [VAC]0 1 6 [DMC]0 89.聚合表观活化能为 4 4 0 1kJ·mol- 1 ,初步探讨了聚合反应机理 .     

新型引发剂引发苯乙烯聚合的动力学

采用过氧化2-乙基己基碳酸叔丁酯为引发剂,研究了苯乙烯自由基本体聚合的动力学过程,考察了引发剂浓度、温度、乙苯质量分数对聚合反应速率和聚苯乙烯分子量的影响.结果表明:在117℃下,聚合速率(Rp)对引发剂浓度的反应级数为0.42,对苯乙烯浓度的反应级数为1,聚合反应的表观活化能为54.8 kJ/mol.引发剂浓度、温度、乙苯质量分数的提高导致聚苯乙烯数均分子量分别下降了约30％、20％和15％,其中引发剂浓度的影响最为显著.     

氯丁胶乳乳液接枝甲基丙烯酸甲酯的反应动力学

采用乳液聚合法将甲基丙烯酸甲酯(MMA)接枝到氯丁胶乳上,红外光谱和核磁共振氢谱证实了接枝产物的生成。 研究了反应温度、乳化剂浓度、引发剂浓度和单体浓度对表观聚合速率的影响。 结果表明,当反应温度为50 ℃,引发剂叔丁基过氧化氢 四乙烯五胺（t-BHP/TEPA）用量为氯丁胶乳干重的0.5%,单体/聚合物质量比m(M)∶m(P)=3∶5,乳化剂十二烷基连苯醚二磺酸钠（DSB）用量为单体总质量1%时,单体转化率和接枝效率分别为99.1%和54.9%。 聚合反应动力学关系式为：Rp=Kc(E)0.15c(I)0.30c(MMA)1.41,式中,K为常数,在40~55 ℃范围内,聚合反应的表观活化能Ea＝60.2 kJ/mol。 接枝聚合基本符合自由基反应机理。     

氯丁胶乳乳液接枝甲基丙烯酸甲酯反应动力学

采用乳液聚合法将甲基丙烯酸甲酯(MMA)接枝到氯丁胶乳上,红外光谱和核磁共振氢谱证实了接枝产物的生成。研究了反应温度、乳化剂浓度、引发剂浓度和单体浓度对表观聚合速率的影响。结果表明,当反应温度为50℃,引发剂叔丁基过氧化氢-四乙烯五胺(t-BHP/TEPA)用量为氯丁胶乳干重的0.5%,单体/聚合物质量比m(M):m(P)=3:5,乳化剂十二烷基连苯醚二磺酸钠(DSB)用量为单体总质量1%时,单体转化率和接枝效率分别为99.1%和54.9%。聚合反应动力学关系式为:Rp=Kc(E)0.15c(I)0.30c(MMA)1.41,式中,K为常数,在40～55℃范围内,聚合反应的表观活化能Ea=60.2kJ/mol。接枝聚合基本符合自由基反应机理。     

淀粉-丙烯酸反相乳液接枝共聚反应的动力学研究

以过硫酸铵(NH4)2S2O8为引发剂,失水山犁醇单月桂酸酯(Span-20)为乳化剂,采用反相乳液聚合技术,制得了淀粉-丙烯酸接枝共聚物,研究了反应温度、引发剂浓度、单体浓度、乳化剂浓度、淀粉用量五种因素对反应速率的影响。根据单体的转化率,用线性回归法计算聚合反应速率;然后用作图法确定反应的动力学关系式,并求出反应起始阶段的表观活化能。结果表明,其动力学关系式为:Rp∝[(NH4)2S2O8]0.51[AA]1.18[St]0.81[Span-20]0.62;聚合反应恒速阶段的活化能,在53~68℃范围内为26.00 kJ.mol-1。     

阳离子型共聚物AM/DMBAC疏水微嵌段结构的分析

利用表面张力法对甲基丙烯酰氧乙基二甲基苄基氯化铵(简称DMBAC)在水溶液中的表面活性进行了测试并确定了其CMC值.研究了丙烯酰胺(AM)和DMBAC在水溶液中的共聚合反应行为,测定了AM与DMBAC共聚反应的竞聚率;IR,1H-NMR对共聚物的结构进行了表征;13C-NMR和DSC分析了单体DMBAC浓度对共聚产物微结构的影响;芘作为荧光探针测定了共聚物水溶液的疏水缔合性质.实验结果表明当共聚单体DMBAC浓度大于CMC时DMBAC倾向于均聚,DMBAC在共聚产物主链上呈微嵌段的形式分布.当共聚单体DMBAC浓度小于CMC时,DMBAC与AM倾向于无规共聚.     

二乙基二烯丙基氯化铵均聚及其与丙烯酰胺或丙烯酸共聚动力学研究

采用膨胀计法研究了以过硫酸铵为引发剂,二乙基二烯丙基氯化铵(DEDAAC)在水溶液中的均聚及其与丙烯酰胺(AM)和丙烯酸(AA)共聚动力学,测定了相应的聚合表观活化能;采用元素分析法测定了DEDAAC分别与AM和AA在低转化率下共聚物的组成,并采用氯离子选择性电极法测定了DEDAAC-AM共聚物中的氯离子含量,按Kelen-Tudos方法求得了相应的竞聚率.结果表明,DEDAAC均聚速率方程为RP=k[M]0.99[I]0.76,表观活化能Ea=77.00kJ/mol,说明链终止为单基终止和双基终止并存,引发过程与单体浓度无关;DEDAAC与AM在摩尔比为4∶1时,共聚动力学方程为RP=[M]2.53[I]0.90,表观活化能Ea=67.06kJ/mol,单体竞聚率为rDE=0.31±0.02、rAM=5.27±0.53;DEDAAC与AA在摩尔比为4∶1时,共聚动力学方程为RP=k[M]2.94[I]0.83,表观活化能Ea=70.07kJ/mol,竞聚率为rDE=0.28±0.03、rAA=5.15±0.28;DEDAAC与AM和AA等共聚为非理想共聚,得到的产物均为无规共聚物.     

丙烯酰胺与二甲基二烯丙基氯化铵共聚动力学

采用膨胀计法研究了以过硫酸铵 亚硫酸氢钠为引发剂,丙烯酰胺（AM）和二甲基二烯丙基氯化铵（DMDAAC）在水溶液中的共聚反应动力学,测定了相应的聚合表观活化能、聚合速率方程和单体竞聚率。 结果表明,当AM与DMDAAC摩尔比分别为5∶5、6∶4和7∶3时,表观活化能分别为Ea1=90.61 kJ/mol、Ea2=88.88 kJ/mol和Ea3=85.15 kJ/mol;聚合反应温度为45 ℃下,聚合速率方程分别为Rp1=kc(M)2.84c(IO)0.51·c(IR)0.61,Rp2=kc(M)2.77c(IO)0.51c(IR)0.59和Rp3=kc(M)2.73c(IO)0.50c(IR)0.56;2种单体的竞聚率分别为rAM=6.11,rDMDAAC=0.14。 上述实验结果可从动力学角度为不同阳离子度共聚物Poly(DMDAAC-co-AM)（PDA）聚合反应速率差别及产物特征黏度值差异进行解释。     

Living radical copolymerization of styrene/maleic anhydride

Styrene/maleic anhydride (MA) copolymerization was carried out using benzoyl peroxide (BPO) and 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO). Styrene/MA copolymerization proceeded faster and yielded higher molecular weight products compared to styrene homopolymerization. When styrene/MA copolymerization was approximated to follow the first‐order kinetics, the apparent activation energy appeared to be lower than that corresponding to styrene homopolymerization. Molecular weight of products from isothermal copolymerization of styrene/MA increased linearly with the conversion. However products from the copolymerization at different temperatures had molecular weight deviating from the linear relationship indicating that the copolymerization did not follow the perfect living polymerization characteristics. During the copolymerization, MA was preferentially consumed by styrene/MA random copolymerization and then polymerization of practically pure styrene continued to produce copolymers with styrene‐co‐MA block and styrene‐rich block. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2239–2244, 2000     

丙烯酰胺与N,N′-亚甲基双丙烯酰胺的共聚反应研究

本文利用凝胶模量测定法、气相色谱法和紫外光谱法对丙烯酰胺与N,N’-亚甲基双丙烯酰胺水溶液共聚反应进行了研究,证实了N,N’-亚甲基双丙烯酰胺的反应活性明显大于丙烯酰胺的反应活性。用气相色谱法测得单体的竞聚率分别为r_(AM)=0.117,,r_(Bis)=5.756;用紫外光谱法研究了聚合反应中氧化还原引发剂浓度和反应温度对聚合反应速率的影响,得出共聚反应速率方程中,氧化剂的方次为0.66,还原剂浓度的方次为0.55,并求出共聚反应表现活化能为37.1KJ/mol。     

Kinetics of ethylene polymerization reactions with chromium oxide catalysts

Principal kinetic data are presented for ethylene homopolymerization and ethylene/1‐hexene copolymerization reactions with two types of chromium oxide catalyst. The reaction rate of the homopolymerization reaction is first order with respect to ethylene concentration (both for gas‐phase and slurry reactions); its effective activation energy is 10.2 kcal/mol (42.8 kJ/mol). The r₁ value for ethylene/1‐hexene copolymerization reactions with the catalysts is ～30, which places these catalysts in terms of efficiency of α‐olefin copolymerization with ethylene between metallocene catalysts (r₁ ～ 20) and Ti‐based Ziegler‐Natta catalysts (r₁ in the 80–120 range). GPC, DSC, and Crystaf data for ethylene/1‐hexene copolymers of different compositions produced with the catalysts show that the reaction products have broad molecular weight and compositional distributions. A combination of kinetic data and structural data for the copolymers provided detailed information about the frequency of chain transfer reactions for several types of active centers present in the catalysts, their copolymerization efficiency, and stability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5315–5329, 2008     

A semiempirical quantum mechanical study of cationically catalyzed homopolymerization and copolymerization of vinyl ethers and epoxides

The purpose of this study was to use the semiempirical quantum mechanical computational method, AM1, to investigate vinyl ether cationic homopolymerization, epoxide homopolymerization, and copolymerization of selected vinyl ethers with a model epoxide (cyclohexene oxide). Homopolymerization studies of 19 vinyl ethers showed that activation enthalpies ranged between 0.0 and 15 kcal/mol, and that the enthalpies of reaction for homopolymerization were nearly all exothermic. Homopolymerization of three epoxides predicted low activation enthalpies, some of which were virtually activationless. All ring-opening epoxide polymerizations were exothermic. Copolymerization of three vinyl ethers with cyclohexene oxide gave activation enthalpies that varied between 2.7 and 4.0 kcal/mol, and the enthalpies of reaction for copolymerization were all exothermic.     

In situ monitoring of coordination copolymerization of butadiene and isoprene via ATR-FTIR spectroscopy

<正>FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance(ATR) immersion probe was utilized to study in situ the copolymerization of butadiene(Bd) and isoprene(Ip) with neodymium-based catalyst in hexane. The relationship between the signal intensity of monomer and its concentration was investigated.The kinetic study of copolymerization of Bd and Ip was further conducted,and the monomer reactivity ratios were determined via in situ ATR FTIR.The signal band at 1010 cm~(-1) was assigned to wagging vibration of Bd and its intensity was proportional to Bd concentration([Bd]) in the range of 0.46-3.88 mol·L~(-1).The signal bands at 890 and 989 cm~(-1) were assigned to wagging vibration of Ip and the signal intensity was also proportional to Ip concentration([Ip]) in the range of 0.08-4.73 mol·L~(-1) at 890 cm~(-1) and 0.08-7.49 mol·L~(-1) at 989 cm~(-1),respectively.Thus the signal band at 1010 cm~(-1) was chosen to monitor Bd concentration and bands at 989 and 890 cm~(-1) to monitor Ip concentration during the copolymerization,respectively.It was demonstrated that the conversions of Bd and Ip calculated from FTIR data agreed very well with those obtained gravimetrically.The polymerization rates were first order with respect to both[Bd]and[Ip],respectively at different polymerization temperatures.The apparent propagation activation energy for Bd and Ip could be determined to be 54.4 kJ·mol~(-1) and 57.7 kJ·mol~(-1),respectively.The monomer reactivity ratios were calculated to be 1.08 for Bd(r_(Bd)) and 0.48 for IP(r_(Ip)) based on FTIR data.The Bd-Ip copolymer products with random sequence could be obtained with only one glass transition temperature.     

丙烯酰胺与N,N′-亚甲基双丙烯酰胺的共聚反应研究

 本文利用凝胶模量测定法、气相色谱法和紫外光谱法对丙烯酰胺与N,N’-亚甲基双丙烯酰胺水溶液共聚反应进行了研究,证实了N,N’-亚甲基双丙烯酰胺的反应活性明显大于丙烯酰胺的反应活性。用气相色谱法测得单体的竞聚率分别为r_AM=0.117,,r_Bis=5.756;用紫外光谱法研究了聚合反应中氧化还原引发剂浓度和反应温度对聚合反应速率的影响,得出共聚反应速率方程中,氧化剂的方次为0.66,还原剂浓度的方次为0.55,并求出共聚反应表现活化能为37.1KJ/mol。