Thermally expandable microspheres based on fully or partially bio‐based polymers

Abstract Bio‐based or partially bio‐based thermally expandable microspheres (TEMs) were synthesized by suspension (co)polymerization of the bio‐based monomer α‐methylene‐γ‐valerolactone (MeMBL) together with acrylonitrile and/or methyl methacrylate to form expandable core/shell particles by encapsulating a hydrocarbon‐based blowing agent. The core/shell polymers were characterized with respect to their chemical structure, thermal expansion, and morphology. The obtained particles, TEMs, showed an increasing onset expansion temperature with increasing content of MeMBL owing to the high glass transition temperature of PMeMBL. As a result, bio‐based/partially bio‐based TEMs are achieved with high thermal stability and expansion properties which can be tailored for various applications.