Microstructural dependance of nonlinear optical (NLO) properties of Poly (Styrene-co-Methylmethacrylate) (P(St-co-MMA)/Cupric Oxide (CuO) and Poly(styrene-co-Acrylonitrile) (PSAN)/CuO polymer nanocomposites (PNCs) has been explored. The positron lifetime parameter viz., free volume hole size (V) and NLO parameters viz., third-order nonlinear absorption coefficient () and nonlinear refractive index () are maximum at 0.4 wt% and 1.0 wt% of CuO nanoparticles loadings in P(St-co-MMA)/CuO and PSAN/CuO PNCs respectively. The crystallinity and optical energy band gap decreased in P(St-co-MMA)/CuO and PSAN/CuO PNCs at 0.4 wt% and 1.0 wt% of CuO nanoparticles loading respectively. The reduced optical energy band gap and the formation of bigger free volumes promote the dipole polarization and therefore the NLO properties of P(St-co-MMA)/CuO and PSAN/CuO PNCs.

中文翻译：

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自由体积对P(St-co-MMA)/CuO和PSAN/CuO聚合物纳米复合材料非线性光学特性的影响

聚(苯乙烯-甲基丙烯酸甲酯) (P(St-co-MMA)/氧化铜 (CuO) 和聚(苯乙烯-丙烯腈) (PSAN)/CuO 聚合物纳米复合材料的非线性光学 (NLO) 性能的微观结构依赖性 (正电子寿命参数，即自由体积孔尺寸 (V) 和 NLO 参数，即三阶非线性吸收系数 () 和非线性折射率 () 在 0.4 wt% 和 1.0 wt% 时最大P(St-co-MMA)/CuO 和 PSAN/CuO PNC 中的 CuO 纳米颗粒负载量分别为 0.4 wt%，P(St-co-MMA)/CuO 和 PSAN/CuO PNC 中的结晶度和光学能带隙降低分别负载1.0 wt%和1.0 wt%的CuO纳米粒子。减小的光能带隙和更大的自由体积的形成促进了偶极子偏振，从而提高了P(St-co-MMA)/CuO和PSAN/CuO PNCs的NLO性能。