Yao Jia, Ravi Palaniswamy, Tam Kam C, Gan Leong H
Singapore-MIT Alliance, School of Mechanical and Production Engineering, National Institute of Education, Nanyang Technological University, Singapore 639798.
Langmuir. 2004 Mar 16;20(6):2157-63. doi: 10.1021/la0355343.
The atom transfer radical polymerization technique was used to synthesize the poly(methyl methacrylate-block-methacrylic acid) (P(MAA-b-MMA)) copolymer in order to study the aggregation behavior in aqueous solution over the course of neutralization. Combinations of static and dynamic light scattering (SLS, DLS) and potentiometric titration techniques were used to investigate the size and shape of the micelle at various degrees of neutralization (alpha). By comparing the effect of different polymer chain length with similar MMA/MAA ratio on the aggregation behavior during neutralization, we found relatively strong entanglement of long MMA polymer chains. The comparison between the different MMA/MAA ratios showed that longer MMA chains produced more entanglements. Conductometric titration was used to determine the counterion condensation phenomenon during the course of neutralization. At a critical micellar charge density observed at alpha approximately 0.4, Na+ ions are condensed on the polymer chains. The amount of condensed Na+ was evaluated by the conductivity change, yielding the condensation ratio when the polymer was completely neutralized.
采用原子转移自由基聚合技术合成了聚（甲基丙烯酸甲酯-嵌段-甲基丙烯酸）（P（MAA-b-MMA））共聚物，以研究其在中和过程中在水溶液中的聚集行为。结合静态和动态光散射（SLS、DLS）以及电位滴定技术，研究了不同中和度（α）下胶束的尺寸和形状。通过比较具有相似MMA/MAA比例的不同聚合物链长对中和过程中聚集行为的影响，我们发现较长的MMA聚合物链存在较强的缠结。不同MMA/MAA比例之间的比较表明，较长的MMA链产生更多的缠结。采用电导滴定法测定中和过程中的反离子凝聚现象。在α约为0.4时观察到的临界胶束电荷密度下，Na+离子凝聚在聚合物链上。通过电导率变化评估凝聚的Na+量，得到聚合物完全中和时的凝聚比。
