防污剂在溶胀聚合物中扩散的模拟研究

Release of the antifoulant in equilibrium swollen polymer:molecular dynamics simulation

利用Materials Studio软件进行分子动力学模拟研究平衡溶胀结构聚合物。调查溶胀前后聚合物玻璃化温度,水与链段在平衡溶胀态下的动力学、不同含水量下水分子的局部动力学和防污剂分子扩散行为,从分子角度解释包覆防污剂的受控释放机制。模拟发现处于平衡溶胀态下,3种P(MMA-co-n-BMA)玻璃化温度分别降低21. 72、17. 27、14. 40 K,水的动力学性质接近本体水,并且高于聚合物链段2个指数;溶胀聚合物处于橡胶态时,防污剂的有效扩散明显增加。结果表明,聚合物的含水量与玻璃化温度是控制防污剂分子扩散的关键因素。

To investigate the release of the antifouling molecules in equilibrium swelling (ES) states, molecular dynamics (MD) simulation was performed to analyze the diffusion of 4, 5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) molecule in P(MMA-co-n-BMA) immersed in water. The glass transition temperature (Tg) was simulated in the dry and equilibrium swelling states, and the dynamics of water and the pendant groups in the ES state were investigated, as well as the influence of water content on the local dynamics of water. The diffusion mechanisms of DCOIT were also analyzed. Tg values of three P(MMA-co-n-BMA)s in the ES state are from 14.84, 17.27 K to 21.73 K lower than in the dry state. Water has the higher mobility than the pendant groups by approx. 2 orders of magnitude in ES systems and has dynamic properties on the same level as those of bulk water. The diffusion of a large-mass penetrant can be controlled effectively with water and Tg as the crucial factors, and the diffusion ability of DCOIT is significantly enhanced when the swollen matrix is in the rubbery state.