Solvent effect on single-chain collapse of poly(methyl methacrylate) in tert-butyl alcohol
Solvent effect on single-chain collapse of poly(methyl methacrylate) in tert-butyl alcohol
复制标题
叔丁醇中溶剂对聚甲基丙烯酸甲酯单链崩解的影响
DOI：
10.1063/1.1539841
复制
发表时间：
2003
影响因子：
4.4
通讯作者：
M. Nakata
中科院分区：
文献类型：
--
作者：
Yoshiki Nakamura;N. Sasaki;M. Nakata
用静态光散射法测定了聚甲基丙烯酸甲酯(PMMA)在纯叔丁醇中线团-微球转变的动力学和静态性质，并与聚甲基丙烯酸甲酯在叔丁醇-水(2.5Vol %)混合溶剂中的动态和静态性质进行了比较，以考察水对链断的影响。在0.6×10−4~2.6×10−4−4 g/cm 3的浓度范围内，测定了分子量M×10−6=4.1和12.2，并测定了温度骤降后的均方回转半径<S2>随时间的变化。当M=1.22×107和M=4.1×106时，PMMA链在猝灭后90分钟内崩塌到平衡球体。由于观察到的相对分子质量的增加，在链崩溃后，由于相分离引起的链聚集变得明显。对于聚甲基丙烯酸甲酯，在混合溶剂叔丁醇-水(2.5Vol %)中，根据分子质量的不同，可以观察到数小时到数周的断链过程。
Kinetic and static properties of the coil–globule transition of poly(methyl methacrylate) (PMMA) in pure tert-butyl alcohol were determined by static light scattering and compared with those of PMMA in the mixed solvent tert-butyl alcohol+water(2.5 vol %) in order to examine the effect of water on the chain collapse. The measurements were carried out for the molecular weight M×10−6=4.1 and 12.2 in the concentration range of 0.6×10−4–2.6×10−4 g/cm3, and the mean-square radius of gyration 〈s2〉 was determined as a function of the time after an abrupt decrease of temperature. PMMA chains collapsed to equilibrium globules within 90 min after quenching for M=1.22×107 and within 30 min for M=4.1×106. Chain aggregation due to phase separation became noticeable after the collapse of the chain because of an increase of observed molecular weight. For PMMA in the mixed solvent tert-butyl alcohol+water(2.5 vol %), the chain collapse process has been observed for periods from hours to weeks depending on the molecular w...