In comparison to uniform foams, structure-gradient foams can offer practical solutions that optimize their resilience and strength. However, controlling the gradient structure is a challenge, especially in silicone rubber (PMVS) based foams. Herein, a facile and eco-friendly one-step supercritical CO (scCO) foaming technique is presented for fabricating structure-gradient PMVS/CNTs composite foams utilizing a non-equilibrium gas concentration profile. Compared with conventional scCO foaming, this method features a more energy-efficient process (lower saturation temperature and time) and results in lighter foam products (density as low as 0.11 g/cm). Moreover, the formation mechanism of gradient cellular structures in PMVS/CNTs foams and the means of adjusting the cell gradient degree are further discussed. Finally, cyclic compression results demonstrate that PMVS/CNTs foams can be optimized to achieve desirable mechanical strength and resilience by adjusting cell gradient degree.

中文翻译：

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通过非平衡气体浓度分布的绿色超临界CO2发泡构建具有理想弹性和强度的结构梯度硅橡胶/碳纳米管泡沫

与均匀泡沫相比，结构梯度泡沫可以提供优化其弹性和强度的实用解决方案。然而，控制梯度结构是一个挑战，特别是在硅橡胶（PMVS）基泡沫中。本文提出了一种简便且环保的一步式超临界 CO (scCO) 发泡技术，用于利用非平衡气体浓度分布制造结构梯度 PMVS/CNT 复合泡沫。与传统的 scCO 发泡相比，该方法具有更节能的过程（更低的饱和温度和时间），并且可以产生更轻的泡沫产品（密度低至 0.11 g/cm3）。此外，还进一步讨论了PMVS/CNTs泡沫中梯度泡孔结构的形成机制以及调节泡孔梯度程度的方法。最后，循环压缩结果表明，可以通过调整泡孔梯度程度来优化 PMVS/CNTs 泡沫，以实现理想的机械强度和回弹性。