Green assessment of polymer microparticles production processes: a critical review

Abstract

The fabrication of simple and core–shell polymer microparticles is of great importance due to their wide range of industrial applications, such as in the food industry, cosmetics, and drug delivery. Regardless of their outstanding advantages, the vast majority of the targeted microparticles are produced using fossil raw materials whose depletion is inevitable, and there is an urgent need to develop innovative classes of sustainable microparticles from renewable resources. Several reviews have discussed the common techniques to synthesize polymer microparticles for diverse real-life applications. Nonetheless, no reports were found on the sustainability evaluation of the diverse production methods or the microparticle raw materials and solvents used. In this critical review, the state of the art of polymer microparticles is first described. Next, the sustainability of the common production techniques, including microfluidics, is evaluated based on selected criteria, including waste generation, use of green solvents, and atom- and energy efficiency. Furthermore, the challenges of achieving green production are discussed based on three elements: green production process, green raw material, and green solvents. Finally, room for improvement is discussed with highlights on future perspectives, including further investigations that should be accomplished to find renewable substitutes and “green up” the existing production strategies for a better life for future generations.