Molecular mobility of peroxy radicals at the ends of isolated polystyrene chains tethered on the solid surface of poly(tetrafluoroethylene) in a vacuum
Molecular mobility of peroxy radicals at the ends of isolated polystyrene chains tethered on the solid surface of poly(tetrafluoroethylene) in a vacuum
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DOI：
10.1021/ma062472p
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发表时间：
2007-03-06
期刊：
影响因子：
5.5
通讯作者：
Iwamura, Takeru
中科院分区：
文献类型：
--
作者：
Sakaguchi, Masato;Yamamoto, Katsuhiro;Iwamura, Takeru
采用电子自旋共振谱研究了真空中温度为10 ~ 250 K的聚四氟乙烯（PTFE）固体表面上孤立聚苯乙烯链（IPSOO）末端过氧自由基的分子迁移率。IPSOO在PTFE表面上的各向异性翻滚运动的起始温度为80 K。当温度高于150 K时，IPSOO从PTFE表面突出，并形成尾状，此时IPSOO处于自由转动状态。火车尾部转变温度定义为160 K，与本体聚苯乙烯（PS）的玻璃化转变温度（373 K）相比极低。计算了尾态IPSO O的活化能为8.3- 9.2kJ/mol。IPSOO的显著高的迁移率和低的活化能可能是由于PTFE表面上的孤立链、低链段密度、链端以及与PTFE表面的弱相互作用。
The molecular mobility of peroxy radicals at the ends of isolated polystyrene chains (IPSOO) tethered on the solid surface of poly(tetrafluoroethylene) (PTFE) was investigated in a vacuum in the temperature range from 10 to 250 K by electron spin resonance spectroscopy. The onset of an anisotropic tumbling motion of IPSOO at a train state on the PTFE surface was 80 K. When the temperature was above 150 K, the IPSOO protruded from the PTFE surface and resulted in a tail state, in which the IPSOO was in a free rotational state. A train-tail transition temperature was defined at 160 K, which was extremely low compared to the glass transition temperature (373 K) of polystyrene (PS) in the bulk. The activation energy of the IPSOO of the tail state was calculated as 8.3-9.2 kJ/mol. The remarkably high mobility and low activation energy of the IPSOO are probably due to an isolated chain on the PTFE surface, a low chain segmental density, a chain end, and a weak interaction with the PTFE surface.