Experimental procedure for achieving multi-graded foams by gas foaming with time-varying boundary conditions

We show that, by ingeniously designing the sorption step, it is possible to achieve non-trivial gas concentration profiles and, correspondingly, at pressure release, foams with density and/or morphology profiles. As a model system, we foamed polystyrene with CO2 and N2, and achieved three- as well as five-layered foams, gradually or sharply graded, yet in a single foaming step (pressure release) executed after different sorption protocols.

本研究表明，通过对吸附步骤进行精巧设计，可获得非平庸的气体浓度分布；相应地，在泄压发泡阶段可得到具备密度与/或形貌分布的泡沫材料。以聚苯乙烯为模型体系，我们采用二氧化碳（CO2）与氮气（N2）作为发泡气体，经不同吸附方案后仅通过单次发泡步骤（即泄压操作），即可制备出梯度渐变或突变的三层及五层泡沫材料。