核壳乳液聚合

1、核壳乳液聚合核壳乳液聚合 Company name核壳乳液聚合1什么是核壳乳液聚合2核壳乳液聚合的核壳结构3影响核壳乳液聚合的因素4核壳乳液聚合运用举例Company name什么是核壳乳液聚合种子乳液聚合所谓种子乳液聚合是先将少量单体按一般乳液聚合法制得种子胶乳(100150nm)。然后将少量种子胶乳(1%3%)，加入正式乳液聚合的配方中。种子胶乳粒将被单体所溶胀并吸附水相中产生的自由基而引发聚合，经过多级溶胀聚合，使粒子逐渐增大，最终可达12m或更大。(普通50-200nm)可用来制备粒径较大、分布较窄的乳胶粒子。在第二步反应中，要控制乳化剂的用量，以抑制新的粒子生成。Company na

2、me什么是核壳乳液聚合核壳乳液聚合核壳乳液聚合是种子乳液聚合的发展。若种子聚合和后继聚合采用不同单体，则形成核壳结构的胶粒，在核与壳的界面上形成接枝层，增加两者的相容性和粘结力，提高力学性能。在总配比完全相同的情况下，因为组分性质的差异，采用种子乳液聚合的方法，控制不同的加料顺序和条件，可以得到结构形态不同的核壳乳胶粒子。与普通乳液乳液聚合相比，它有显著的优越性，如在流变性、最低成膜温度、玻璃转化温度、抗张强度、粘接性能、加工性等方面有显著的特点。Company name什么是核壳乳液聚合种子乳液聚合核壳乳液聚合使粒子长大后继的正式聚合采用同一种单体少量单体先形成种子胶乳形成核壳结构后继聚合采

3、用不同单体少量单体先形成核结构部分Company name核壳乳液聚合的核壳结构乳胶粒的核壳结构：在乳胶粒的中心附近是一个富聚合物的核，其中聚合物含量大而单体含量少。在核的外围是一层富单体的壳;在壳表面上吸附乳化剂分子而成一单分子层，以使该乳胶粒稳定的悬浮在水相中。在核与壳的界面上，分布有正在增长的或失去活性的聚合物末端，聚合反应就是发生在这个界面上。 Company name核壳乳液聚合的核壳结构单体液滴单体液滴种子胶乳单体、乳化剂分别处在水溶液、胶束、液滴三相中的示意图Company name影响核壳乳液聚合的因素根据核和壳单体的不同，正常的核壳聚合物基本上有两种类型：硬核软壳型：这类聚合

4、物主要用作涂料。软核硬壳型：调节玻璃化温度或最低成膜温度。以丁二烯丙烯酸丁酯等软单体，经乳液聚合后为种子，甲基丙烯酸甲酯苯乙烯丙烯睛等为硬单体，后来加入继续聚合，就成为硬壳层。以B（聚丁二烯）为核，S（苯乙烯）和A（丙烯氰）共聚物为壳，就成了著名的ABS工程塑料。Company name影响核壳乳液聚合的因素核壳乳液粒子构成机理接枝机理 一种单体在另一种聚合物存在下进行聚合时，在适当的条件下，会多去聚合物上的活泼氢原子而发生接枝共聚。如St-BA核壳乳液聚合互穿聚合物网络机理 两种聚合物分子链相互贯穿并以化学键的方式各自交联而成的网络结构离子键合机理不同电荷的相互作用Company name影

5、响核壳乳液聚合的因素壳层物质的壳层物质的加料方法加料方法不同，不同，形成的核壳结构和核壳间结合方式也差别很大。形成的核壳结构和核壳间结合方式也差别很大。溶胀法：先不补加引发剂，而加入壳单体，使壳单体溶胀进入乳胶内。这种方法不仅种子乳胶粒表面的单体浓度很高，而且壳单体有充分时间渗入到种子乳胶粒子内部。间歇法：壳单体一次性加入，在引发剂存在下引发聚合，这种方法也使乳胶粒表面单体浓度很高。半连续法：将壳单体连续滴加，使种子乳胶的表面和内部壳单体浓度都很低，既聚合物处在饥渴状态.此只能在核聚合物上连续形成壳层而缺乏核壳层间的结合。Company name影响核壳乳液聚合的因素影响核壳结构的因素除了两中

6、单体的加料次序外，还与单体的亲水性有关。一般乳液聚合都以水为分散介质，亲水性较大的聚合物易和介质水接近，而疏水性倾向于排斥介质水，因而形成不同结构形态的胶乳粒子。正常结构和非正常的结构形态(如翻转形等)乳胶粒。Company name核壳乳液聚合的应用举例（1）多层特种结构聚合物乳胶粒子递变进料、单体A单体B、洋葱当R0：R1=1：2，内部富含B外部富含A的核壳聚合物； 当R0R1，无规共聚物；当R0R1，典型的B核A壳聚合物LOGOLOGO 核壳乳液聚合的应用举例（2）synthesis and application of anionic acrylic（阴离子丙烯酸） emulsion

7、used as paper wet-strength additiveYour site hereLOGORelated imformationvTitlesynthesis and application of anionic acrylic emulsion（阴离子丙烯酸） used as paper wet-strength additivevAuthors Xin Liu, Chunhua Tian, Yuying Wu, Xueming ZhangCollege of Materials Science and Technology, Beijing Forestry Univers

8、ity vFrom 4th International Conference on Pulping,Papermaking and BiotechnologyYour site hereLOGOContents1. Abstract2. Introduction3. Experienment4. Results and discussion5. ConclusionYour site hereLOGOAbstractvpolymerization butyl acrylate (BA) as soft monomer, styrene (St) as hard monomersodium do

9、decyl sulfate (SDS) and dodecyl polyoxy ethylene (OP-10) as emulsifiers under nitrogen丙烯酸丁酯、苯乙烯、十二烷基硫酸钠、烷基酚聚氧乙烯醚vthe optimal conditions the ratio of SDS to OP-10 was 1:2, total dosage was 8%; the dosage of initiator was 0.25 g, including 0.15g in seeded polymerization process and 0.1g in shell polym

10、erization process; the functional monomer dosage was 7.5 g.Your site hereLOGOAbstractvused as wet strength agent single use of APSBM（苯乙烯-丙烯酸丁酯-甲基丙烯酸） was not good simultaneous use of 0.3% APSBM and 0.7% PAE showed great improvement of wet strength to 38% SEM photographs showed that the appearance of

11、 paper treated with 0.7% PAE and 0.3% APSBM had a close crosslinking（交联）Your site hereLOGOIntroduction background1/environmental-friendly products-MF（脲- 甲醛树脂）/UF（三聚氰胺一甲醛树脂）/PAE（聚酰胺环氧氯丙烷）2/excellent penetrability（渗透性）, affinity（亲和力）, and film forming ability;it can disperse in water without organic s

12、olvent3/some disadvantages: high temperature of film forming, lower rigidity（刚度）, tending to get soft, poor water resistance（抗水性） of cured（熟化） film, ect4/One solution to solve above mentioned problemsis to develop special structure of particles called core-shell structure （核壳结构）of the polymer partic

13、lesYour site hereLOGOIntroduction idea a new concept of particle design, that is, changing the structure of latex（胶乳） particles through designing the composition of core and shell structures of latex particles as to improve the properties of emulsion acrylate copolymer（丙烯酸共聚物） emulsion with core-she

14、ll structure was prepared using styrene (St) （苯乙烯）as hard monomer and butyl acrylate (BA) （丙烯酸丁酯）as soft monomer.Your site hereLOGOExperienmentA constitutional formula synthesized by St（苯乙烯）,BA（丙烯酸丁酯） and -MAA（甲基丙烯酸）Your site hereLOGOExperienmentCopolymer synthesis Seed（种子聚合） emulsifier, buffer and

15、distilled water mixed seed monomers, potassium peroxydisulfate（过硫酸钾） Core （核聚合） core monomers which were well pre-emulsified Shell（壳聚合） well pre-emulsified shell monomersYour site hereLOGOExperienmentPaper sheets preparation and analysishardwood bleached kraft pulp(HBKP)（阔叶木漂白硫酸盐浆）80 g/m2 basis weig

16、htWet tensile strength and folding enduranceEmulsion characterizationobservation of emulsions state,viscosity and color; the solid content, conversionmechanical stability, ionic stability, pH stability and storing stability (one month)LOGOLOGOThank You!Your site hereLOGOResults and discussion1/more

17、than 98%2/as the amount of SDS increased, the flocculation of emulsion significantly increased and the storing stability reduced,also the emulsion began to layer.3/same charge causes the bonding of the emulsifier molecules and latex particlesto decline.Your site hereLOGOResults and discussionDuring

18、seed reaction stage, when emulsifier dosage was 3%, the monomer conversion rate was the lowestof all; During core reaction stage, as the reaction went on, the monomer conversion rate increased fast,especially the emulsifier dosage 3% increased significantly; During shell reaction stage, the conversion rate increased slowly; At the end of reaction, the conversion rates of four different emulsifier dosages system were almost the same, which could allreach more than 99%Your