原位接枝聚合改性LDHs/PCL纳米复合薄膜的制备及氧气阻隔性能

Oxygen Barrier Properties of LDHs/PCL Nanocomposite Films Synthesized by In-situ Graft Polymerization

以纳米层状双羟基金属氧化物(LDHs)为引发剂,通过原位聚合的方法在纳米LDHs表面接枝上了聚己内酯(PCL)分子链(LDHs-g-PCL),并将其与纯PCL采用溶液浇筑法制备出LDHs/PCL纳米复合材料,研究了LDHs-g-PCL的化学结构,纳米复合材料的结晶特性、力学性能、阻隔性能等。结果表明,成功制备出化学键合牢固的PCL包覆LDHs;随着LDHs-g-PCL的加入,复合材料的结晶度呈现出逐渐升高的趋势,但异相成核作用效率有一定程度减弱。LDHs-g-PCL的质量分数为10%时,复合材料的拉伸强度和断裂伸长率均达到最大值,相比纯PCL分别提高了31%和37%。LDHs-g-PCL的质量分数为50%时,复合材料对氧气的渗透性达到最低值,相比纯PCL降低程度高达78%,这与层状结构的LDHs显著延长氧气分子在纳米复合材料的曲折渗透路径必不可分。基于Nielsen的相对渗透理论来优化纳米复合材料的渗透模型,结果表明,LDHs/PCL纳米复合材料阻隔性能的提高不仅归结于层状LDHs发挥的阻隔效应,而且更重要的是LDHs-g-PCL加入引起的体积效应。

In this work,layered double hydroxides-g-poly（ε-caprolactone）（LDHs-g-PCL）were prepared by in-situ ringopening polymerization at low LDHs loadings.Then LDHs/PCL nanocomposites were prepared by blending LDHs-g-PCL and pure PCL via solution casting method,and the nanocomposites＇ chemical structures were investigated.And crystallization behavior,mechanical properties and barrier properties of nanocomposites were also deeply studied.It was shown that LDHs-g-PCL were prepared successfully by in-situ polymerization.And results showed that with the increase of LDHs-g-PCL in LDHs/PCL nanocomposites,the crystallization of LDHs/PCL nanocomposites gradually increased.However,the efficiency of heterogeneous nucleation of LDHsg-PCL decreased to a certain extent.Tensile strength and elongation at break of LDHs/PCL nanocomposites containing 10%（mass fraction）LDHs-g-PCL increased by 31% and 37%,respectively.Compared to pure PCL,the O2 permeability of LDHs/PCL nanocomposites containing 50%（mass fraction）LDHs-g-PCL was reduced by nearly 78%.And the reduction of the O2 permeability arised from the longer diffusion path that the pentrants must travel in the presence of LDHs.The relative permeability model of nanocomposites based on Nielsen＇s theory was optimized.According to the optimized model,the key parameters to improve the barrier properties of LDHs/PCL nanocomposites are not only the barrier effect of the LDHs（or LDHs-g-PCL）but also the bulk effect that they develop in the polymer matrix.