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This paper reports an efficient method of preparing porous polymeric microspheres by solvent evaporation in foam phase, in which phase separation between polymer and porogen occurs in foam phase instead of that in water phase by using the traditional solvent evaporation method. The method provides outstanding features, including being time-saving, of high-yield and able for continuous production, in which formation of porous polymeric microspheres finished within 3 min with a high production yield up to approximate 95 wt% and the process was able to be developed into a continuous process for production of porous polymeric microspheres. It was also universal to non-crosslinked polymers since the method is a development on the traditional emulsion solvent evaporation method. The new method is efficient and can be used potentially on the industrial scale for continuous production of porous polymeric microspheres.

A general and versatile strategy to prepare melamine-formaldehyde (MF) microcapsules encapsulating oil-based fragrances by combining solvent evaporation and in situ polymerization was proposed in this work. The oil-based fragrance was pre-encapsulated by an inner polyacrylate membrane via solvent evaporation, followed by in situ polymerization of MF precondensates as an outer shell. The polyacrylate membrane is used as an intermediate bridging layer to stabilize the oil-based fragrance, and to provide driving forces for in situ polymerization of MF precondensates through electrostatic attractions between carboxyl groups and ammonium ions. It was demonstrated that MF microcapsules containing clove oil were prepared successfully. The amount and the composition of the intermediate polyacrylate bridging layer were critical. Smooth and sphere-shaped MF-clove oil microcapsules were prepared when the weight ratio of polyacrylate to clove oil was over 60 wt% and the concentration of acrylic acid (AA) increased to 10 wt% in polyacrylate. In addition, MF microcapsules containing sunflower oil and hexyl salicylate were prepared by using this method. The work suggests that this new approach can be potentially used to encapsulate various core materials, tuning the shell properties of microcapsules such as thickness, mechanical strength and release properties.