Designing Semiencapsulation Based Covalently Self-Healable Poly(methyl methacrylate) Composites by Atom Transfer Radical Polymerization

Self-healable poly(methyl methacrylate) (PMMA) composites were fabricated with embedded glycidyl methacrylate (GMA) encapsulated poly(melamine-formaldehyde) microcapsules. The matrix polymers were synthesized via Atom Transfer Radical Polymerization using two different initiators; one linear and another hexafunctional. As the so prepared polymer matrix retains living characteristics, it can initiate a healing reaction when the encapsulated monomer reaches the matrix due to formation or extension of a crack and thus healing the system covalently. The effect of number of initiating functionality on healing characteristic was studied using both linear and 6-armed star PMMA having same targeted molecular weight. Both the systems were able to restore 100% original fracture toughness after healing. However, the polymer matrix prepared by hexafunctional initiator restored the fracture toughness much faster than that of the linear polymer matrix. (C) 2016 Wiley Periodicals, Inc.