摘要 |
The invention provides a method of making a material comprising the steps of: coating a support with a solution comprising a polymer, a blowing agent and a surfactant. Either prior to or after the step of coating the support, the solution is interacted with to cause the blowing agent to generate bubbles within the solution causing foaming of the polymer. The surfactant is selected in dependence on whether or not it satisfies one or more predetermined criteria, to control the size of the bubbles.
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