微波聚合制备单分散、超细聚甲基丙烯酸甲酯微球

在微波辐照下,通过甲基丙烯酸甲酯(MMA)的无乳化剂乳液聚合,制备出粒径单分散、超细聚甲基丙烯酸甲酯(PMMA)微球。微波显著缩短聚合诱导期,加快聚合反应,其部分原因是微波加快引发剂过硫酸钾(KPS)的分解。实验证明微波辐照下KPS的表观分解活化能(ED)由128.3kJ/mol降低到106.0kJ/mol。单体浓度是影响PMMA乳液粒子尺寸的主要因素,在[MMA]小于0.3mol/L时,平均粒径随单体浓度提高而线形增加;[MMA]为0.3～1.0mol/L时,平均粒径稳定在约200nm;之后随单体浓度进一步增加,乳液稳定性变差。引发剂浓度增加对平均粒径影响较小,但增大引发剂浓度可显著降低粒径分散度。选取[MMA]为0.23～0.3mol/L、[KPS]为3×10-3～6×10-3mol/L可以得到粒径200nm的单分散微球。以丙酮/水(体积比1/3)为反应介质,可制备出数均粒径45nm的PMMA纳米粒子。在体系中加入3.5×10-3mol/L的Cu2+,可制备出数均粒径67nm、单分散的PMMA纳米粒子。     

消除夹带溶胀的新液膜操作法

消除夹带溶胀的新液膜操作法曹汉瑾，褚莹，何彦涛，吴子生，严忠（东北师范大学化学系长春１３００２４）关键词液膜，油／水乳液，溶胀，夹带，包裹消除液膜操作中的夹带溶胀对液膜的工业化具有重要意义，夹带溶胀分为包裹溶胀和再液化溶胀。前者是乳状液滴上浮时将水相...     

Synthesis of saccharidic polymer colloids via free radical mini‐emulsion polymerization

Polymer colloids based on 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D ‐glucofuranose (3‐MDG) and butyl acrylate (BA) were prepared via free radical mini‐emulsion polymerization. The kinetic and colloidal features of the copolymerization were investigated. The final particle size (D) of the sugar latexes is inversely proportional to the concentration of the anionic emulsifier (sodium dodecyl sulphate, SDS) and the non‐ionic one (alkyl polyglucoside, APG). It was also found that D is independent of the concentration of either the water‐soluble initiator (potassium persulfate, KPS), or the oil‐soluble initiator (2,2′‐azobisisobutyronitrile, AIBN). The rate of mini‐emulsion polymerization is lower in comparison with the conventional emulsion polymerization under the same conditions. The polymerization rate (R_p) and the total number of particles (N_p) are proportional to the 0.72th and 0.93th power of the SDS, and to the 1.40th and 2.22th of the APG concentration. Following reaction orders, 0.79/0.06 were obtained for R_p/N_p versus the concentration of KPS, and 0.22/?0.01 for AIBN, respectively. Copyright © 2004 John Wiley & Sons, Ltd.     

Preparation of poly(N‐ethyl methacrylamide) particles via an emulsion/precipitation process: The role of the crosslinker

Monodisperse, thermosensitive poly(N‐ethyl methacrylamide) microgel particles were prepared by the batch precipitation/emulsion polymerization of water‐soluble N‐ethyl methacrylamide and the hydrophobic crosslinker ethylene glycol dimethacrylate initiated by potassium persulfate. Particular attention was paid to the effect of the crosslinker agent on the polymerization process (kinetics, conversion, and water‐soluble oligomer content). Particles were characterized in terms of their size distribution and swelling capacity. A polymerization mechanism for the water‐soluble monomer and non‐water‐soluble crosslinker is proposed and discussed on the basis of a combination of both emulsion and precipitation polymerization processes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1808–1817, 2002     

原油乳状液破乳的动态法研究

The stability of different crude oil emulsions from ASP flooding production well is studied by the method of a stirred tank. The demulsifying of crude-oil emulsion by different demulsifying agents is discussed. The breakage of the crude oil emulsions from the well PO11 by the different types and concentrations of the emulsifying agents is also discussed. The breaking mechanism of the demulsifying agent is described microscopically.     

MAA存在下VAc/BA核壳乳液聚合过程中的胶粒形态研究

用ＴＥＭ和电位滴定法对不同配方和工艺条件得到的胶粒形态结构和羧基分别进行了表征。结果表明：加入甲基丙烯酸有利于胶粒的稳定和形成规则的核壳胶粒。半连续加料不会形成完全反转的核壳结构,但是,核层在反应过程中由于聚合物簇的迁移会造成形变。由于胶粒中聚合物浓度高,粘度大,因而胶粒形态变化受动力学影响甚大,羧基分布主要是由动力学确定的。     

KPS—CuSO4—Na2SO3参与的无皂液聚合

研究了MMA-St在氧化还原引发剂KPS-CuSO_4-Na_2SO_3存在下的快速无皂乳液聚合.当[MMA]=0.51mol/L、[St]=0.49 mol/L、70℃对,在[KPS]=2.77×10~(-3)mol/L、[CuSO_4]=1.50×10~(-5)mol/L、[Na_2SO_3]=2.77×10~(-3) mol/L条件下反应100min,转化率大于90％;讨论了胶乳的分子量及其分布;求出了聚合反应活化能E_a=81.6 kJ/mol和聚合反应速率常数k_p=321.9 L/mol·s.     

纳米氧化锌的乳液合成、结构表征与气敏性能

利用化学沉淀法、乳液法及微乳液法合成了不同晶粒尺寸的纳米氧化锌气敏材料；用X射线衍射和透射电镜、研究了材料的晶体结构和陶瓷微结构，并利用科西-科西法和德拜-谢乐法计算了材料的平均晶粒度和晶格畸变；和静态配气法测试了材料对乙醇、汽油、氢气、丁烷、六氟化硫的气体灵敏度。实验结果表明：微乳液法和阴离子表面活性剂乳化法合成的氧化锌具有颗粒小，气体灵敏度高和工作温度低的特点。     

二烯丙基二甲基氯化铵—丙烯酰胺反相乳液聚合的动力学特征研究

采用油酸失水山梨醇酯（ＳＰＡＮ）－壬基酚聚氧化乙烯醚（ＯＰ）复合乳化剂与Ｋ２Ｓ２Ｏ８－Ｎａ２ＳＯ３氧化还原引发剂，进行二烯丙基二甲基氯化铵－丙烯酰胺反相乳液共聚合，测得单体的竞聚率为γＤＡＤＭＡＣ＝０．１４±０．１１，γＡＭ＝５．０５±０．６６；在单体浓度为２５─４５％，引发剂浓度０．０６—０．１％，乳化剂浓度为５—９％，聚合温度３０３Ｋ条件下，得到了共聚反应动力学方程：Ｒｐ＝ｋ［Ｍ］０．６８［Ｉ］１．３１［Ｅ］０．７３，文中对上述结果做了解释．     

采用新型引发剂乳液聚合法合成高相对分子质量聚乙烯醇

采用新型引发剂偶氮二异(N-胺乙基)丁脒(ABEA)对醋酸乙烯酯的低温乳液聚合进行了研究。通过正交试验得出了高相对分子质量聚醋酸乙烯酯的最佳工艺配方。讨论了引发剂浓度、反应温度和乳化剂浓度对聚合物相对分子质量和转化率的影响。对高相对分子质量聚醋酸乙烯酯醇解工艺进行了探讨,并获得了聚合度为3500~4000的聚乙烯醇。