Ring Structures of Silicone Oligomers：a Density Functional Theory Study

• Published in: 东华大学学报（英文版） Vol. 34; no. 5; pp. 646 - 652
• Main Author: 程学礼;赵燕云;韩银峰;张建平
• Format: Journal Article
• Language: English
• Published: School of Chemistry and Chemical Engineering, Taishan University, Tai'an 271000, China 31.10.2017
• Subjects: stacked structure; B3LYP; silicone; linear strand; ring structure
• ISSN: 1672-5220
• DOI: 10.3969/j.issn.1672-5220.2017.05.006

Silicones can be cross-linked to materials with a wide variety of properties.In this work,the ringed oligomers of [SiO（OH）2]nas well as the stacked structures of trimer and the linear strands of the dimer and trimer were investigated systematically at B3 LYP/6-311 ＋ ＋ G（d,p） level combined with the conductor-like screening model（CPCM）.This theoretical model reveals that,（1） SiO（OH）2 will condense to stable ringed structures with SiO tetrahedrons;（2） in the ringed octamer [SiO（OH）2]8,the macrocycle begins to pucker drastically;（3） from the linear strands of SiO rings it can be seen that the longer the chain is,the greater the energies decrease;（4） in [SiO（OH）2]n（n ≥5） and in the strands of ringed oligomers,the highest occupied molecular orbitals（HOMOs） are primarily the n orbitals of the lone-pair electrons of oxygen atoms,so there are no delocalized π bonds.