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首页> 外文期刊>Macromolecular theory and simulations >A first principle characterization of polyethylene, poly(propylene) and polystyrene macroradicals properties
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A first principle characterization of polyethylene, poly(propylene) and polystyrene macroradicals properties

机译：聚乙烯，聚（丙烯）和聚苯乙烯大自由基特性的第一原理表征

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Structures of polyethylene, poly(propylene) and polystyrene macroradicals have been studied by means of the B3LYP/6-31G** method. The polystyrene tertiary alkyl radical has been found to be less active as having spin density partially delocalized on the aromatic ring neighboring to the radical site. Considering the main chain bond orders, the following radicals have been found to be susceptible to main chain scission: the sec- and tert-oxyl poly(propylene) ones, the sec- and tert-oxyl polystyrene ones as well as the tertiary alkyl polystyrene one. The energy levels of the last frontier molecular orbitals in the polyolefin macroradicals have been found to be split up and moved-up and down for HOMOs and LUMOs, respectively. The alkyl macroradicals have single occupied molecular orbital with increased energy. In the oxyl and peroxyl radicals the spin density comes from two or three last orbitals that are spread over a broad molecular region and no single occupied molecular orbital (SOMO) may be identified.
机译：聚乙烯，聚（丙烯）和聚苯乙烯大自由基的结构已通过B3LYP / 6-31G **方法进行了研究。已经发现聚苯乙烯叔烷基自由基具有较低的活性，因为其自旋密度在离该自由基位点相邻的芳环上部分离域。考虑到主链键序，发现以下基团易于发生主链断裂：仲和叔氧基聚（丙烯）基，仲和叔氧基聚苯乙烯基以及叔烷基聚苯乙烯一。已经发现，对于HOMO和LUMO，聚烯烃大基中最后一个前沿分子轨道的能级分别向上和向下移动。烷基大自由基具有增加的能量的单个占据的分子轨道。在氧基和过氧自由基中，自旋密度来自两个或三个最后一个轨道，这些轨道分布在宽阔的分子区域上，无法确定单个占据的分子轨道（SOMO）。

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