基于密度泛函理论的外电场下双酚A型环氧树脂分子的结构及特性

采用密度泛函m062x的方法在6-31g(d)基组上对双酚A型环氧树脂分子进行优化得到了它的稳定结构,并且研究了不同外电场(0-0.013 a.u., 1 a.u.=5.142×10~(11) V/m)作用下双酚A型环氧树脂分子的分子结构、电偶极矩和分子总能量,偶极矩、极化率、前线轨道的能级和成分,原子之间的键能和红外光谱的变化.研究表明:随着外加电场的增大,双酚A型环氧树脂分子从倒V型结构逐渐变成线性结构,总能量降低,偶极矩和极化率都升高,且双酚A型环氧树脂分子的稳定性随着外加电场的增大而降低;最高占据轨道能级随着外加电场的增大而增大,沿逆电场方向分子链端表现出亲核反应活性,最低空轨道能级随着外加电场的增大而减小,沿电场方向分子链端表现出亲电反应;位于分子两端环氧基团上的C-C,C-O容易发生断裂,进而破环了双酚A型环氧树脂分子的稳定性;分子红外光谱在高频区的吸收峰出现了明显的红移现象.

Structure and Properties of Bisphenol A Type Epoxy Resin Molecule under External Electric Field Based on Density Functional Theory

The stable structure of bisphenol A type epoxy resin molecule was obtained by density functional m062x optimization on 6-31g(d) basis set. The molecular structure, electric dipole moment and total molecular energy, dipole moment, polarizability, energy level and composition of frontier orbital, bond between atoms of bisphenol A type epoxy resin molecule under different external electric fields (0-0.013 a.u., 1 a.u. = 5.142×1011V/m) were studied. The results show that with the increase of applied electric field, the bisphenol A type epoxy resin molecule gradually changes from inverted V structure to linear structure, the total energy decreases, the dipole moment and polarizability increase, and the stability of bisphenol A type epoxy resin molecule decreases with the increase of applied electric field. The highest occupied orbital level increases with the increase of applied electric field, and the molecular chain end shows nucleophilic reactivity along the direction of inverse electric field, while the lowest empty orbital level decreases with the increase of applied electric field, and the molecular chain end shows electrophilic reactions along the direction of electric field. C-C and C-O on the epoxy groups at both ends of the molecule are liable to break, thus breaking the stability of bisphenol A type epoxy resin molecule. The absorption peaks of molecular infrared spectroscopy show obvious red shift in the high frequency region.