Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409-0010, USA.
Langmuir. 2010 Apr 6;26(7):5226-31. doi: 10.1021/la903705p.
The effect of surface treatment on the dynamics of adsorbed poly(methyl acrylate) (PMA) was studied using deuterium NMR and temperature-modulated differential scanning calorimetry (TMDSC). The solid-state deuterium NMR experiments were performed using PMA-d(3), deuterated on the methyl group. The line shape changes for PMA-d(3) were followed as a function of temperature and compared for the polymer on untreated silica, organically modified (treated) silica (reacted with hexamethyltrisilazane), and in bulk. The dynamics of PMA-d(3) on treated silica was found to be intermediate between that of the polymer adsorbed on untreated silica and that of the bulk polymer, i.e., the treated silica caused a restriction on the dynamics of the polymer as compared to bulk, but not as dramatically as that on untreated silica. Similar to the dynamics on untreated silica, the dynamics on treated silica showed a broad heterogeneity with a superposition of more-mobile and less-mobile components. Two molecular mass samples were also studied (38 and 77 kDa) with the molecular mass dependence on the treated or untreated silica being weaker than that in bulk. The TMDSC thermograms of the samples were consistent with the NMR results, with the glass transition region for the PMA-d(3) on the treated silica being in between that of the bulk and that on the untreated silica.
使用氘核 NMR 和温度调制差示扫描量热法（TMDSC）研究了表面处理对吸附聚甲基丙烯酸酯（PMA）动力学的影响。固态氘核 NMR 实验使用氘代甲基的 PMA-d(3)进行。随着温度的变化，跟踪 PMA-d(3)的线形变化，并将其与未处理的二氧化硅、有机改性（处理）的二氧化硅（与六甲基二硅氮烷反应）和本体聚合物上的 PMA-d(3)进行比较。结果表明，处理后的二氧化硅上 PMA-d(3)的动力学介于未处理的二氧化硅上吸附聚合物和本体聚合物之间，即处理后的二氧化硅对聚合物的动力学产生了限制，但其限制程度不如未处理的二氧化硅那么显著。与未处理的二氧化硅上的动力学相似，处理后的二氧化硅上的动力学也表现出广泛的不均匀性，存在更移动和更少移动的成分的叠加。还研究了两个分子量样品（38 和 77 kDa），与本体相比，处理或未处理的二氧化硅上的分子量依赖性较弱。样品的 TMDSC 图谱与 NMR 结果一致，处理后的二氧化硅上 PMA-d(3)的玻璃化转变区域介于本体和未处理的二氧化硅之间。
