Effects of molecular mass and surface treatment on adsorbed poly(methyl methacrylate) on silica
Effects of molecular mass and surface treatment on adsorbed poly(methyl methacrylate) on silica
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分子量和表面处理对二氧化硅吸附聚甲基丙烯酸甲酯的影响
DOI：
10.1002/polb.21400
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
P. Krisanangkura
中科院分区：
文献类型：
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作者：
Moses T. Kabomo;Moses T. Kabomo;F. Blum;Suntree Kulkeratiyut;Suntree Kulkeratiyut;Suntree Kulkeratiyut;Suriyaphongse Kulkeratiyut;Suriyaphongse Kulkeratiyut;Suriyaphongse Kulkeratiyut;P. Krisanangkura
使用调制差示扫描量热法和 FTIR 研究了二氧化硅上相对单分散吸附的聚甲基丙烯酸甲酯 (PMMA) 样品（19 至 587 kDa）的行为。未经处理的 Cab-O-Sil 二氧化硅的玻璃化转变温度 (T g S) 比相应的块状样品更高（约 30 °C），并且转变范围明显更宽（5-6 倍）。虽然本体聚合物的 T g S 显示出预期的对分子量的依赖性，但未处理二氧化硅上的聚合物几乎没有显示出依赖性，即在相同的吸附量下，玻璃化转变非常相似。吸附的 PMMA（在未处理的二氧化硅上）的 FTIR 光谱显示存在至少两个共振，一个用于结合（与表面硅烷醇键合的氢），另一个用于游离羰基。光谱拟合可以估计羰基的结合分数，该分数取决于吸附量，而不是分子质量。在用六甲基二硅氮烷 (HMDS) 处理的 Cab-O-Sil 上，吸附的 PMMA 表现出玻璃化转变行为，且分子质量依赖性很小；不同 PMMA 样品的 T g S 与高分子量本体聚合物的 T g S 非常相似，但额外加宽了约 2 倍。经过处理的二氧化硅上的 PMMA 样品的 FTIR 光谱没有显示出大量的任何氢键羰基。
The behavior of relatively monodisperse adsorbed poly(methyl methacrylate) (PMMA) samples, from 19 to 587 kDa on silica, was studied using modulated differential scanning calorimetry and FTIR. On untreated Cab-O-Sil silica, the glass transition temperatures (T g S) were higher (by around 30 °C), and the transitions were significantly broader (by a factor of 5-6) than those for the corresponding bulk samples. While the T g S for the bulk polymers showed the expected dependence on molecular mass, the polymers on untreated silica showed little dependence, i.e., at the same adsorbed amounts, the glass transitions were very similar. The FTIR spectra of the adsorbed PMMA (on untreated silica) showed the presence of at least two resonances, one for the bound (hydrogen bonded to surface silanols) and another for free carbonyls. Fitting of the spectra allowed the estimation of the bound fractions of carbonyls that were dependent on the adsorbed amount, but not molecular mass. On Cab-O-Sil treated with hexamethyldisilizane (HMDS), the adsorbed PMMA exhibited glass transition behavior with little molecular-mass dependence; the T g S for the different PMMA samples were very similar to those of the high-molecular mass bulk polymer, but with additional broadening of about a factor of 2. FTIR spectra for the PMMA samples on the treated silica did not show significant amounts of any of the hydrogen-bonded carbonyl groups.