Preparation And Properties Of Poly(Methyl Methacrylate) Via Hindered Urea Bond Crosslinking

Poly（methyl methacrylate）（PMMA）is an important engineering plastic that has numerous applications.However,owing to its poor mechanical strength,highly brittle nature,inferior environmental resistance,its practical usage is limited.Diverse research efforts towards making PMMA more robust,tough and environmentally resistant,while retaining its optical characteristic and recyclability are currently underway worldwide.However,because of the mutually exclusive properties of stiffness/strength and toughness,as well as the intrinsic gap between thermoplastics and thermosets,it is difficult to simultaneously optimize them.Herein,we report a straightforward,catalyst-free,fast and efficient preparation of colorless and transparent high performance PMMA using commercially available reagents via hindered urea bonds（HUBs）crosslinking strategies.Implanting HUBs crosslinks into PMMA networks substantially improved Young’s modulus,tensile strength,strain at break,and toughness in comparison with those of thermoplastic PMMA.Specifically,the Young’s modulus,tensile strength,strain at break and toughness of the material with the optimal ratio(HUB-C_0.1 PMMA)are 1.43,1.66,6 and 15.8 times of those of pure PMMA,respectively.More importantly,HUBs cross-linked PMMA achieved a brittle-to-ductile transition,suppressing catastrophic fractures.Additionally,HUBs cross-linked PMMA exhibited excellent solvent,high temperature creep resistance and retained mechanical/appearance stability under harsh conditions,like conventional thermosets,which could be recycled and repaired via the reversible exchange reaction of HUBs crosslinks.Results of this work provide an unfilled strategy for the construction of high performance sustainable PMMA with potential to be extended to other commercial thermoplastics.