Synthesis and characterization of novel star-like PEO-PMMA based copolymers

Star-shaped copolymers based on the linear core poly(ethylene oxide)-poly(propylene oxide) triblock (PEO-b-PPO-b-PEO) and poly(methyl methacrylate) (PMMA) arms were synthesized via a divergent approach. The PEO based chain was firstly dendronized with a polyester system that increased the number of hydroxyl groups per each terminal chain affording cores of generation 1 (G1, two hydroxyl groups per terminal chain) and 2 (G2, four hydroxyl groups per terminal chain). These were used as macroinitiators in the Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate. The copolymers, characterized by different number and length of PMMA blocks, were studied by 1H-NMR, GPC, DSC. A study of influence of architecture on physical properties such as mechanical properties, water sorption and oxygen permeability, was also performed. It was found that both oxygen permeability and water sorption are enhanced with respect to the PMMA homopolymer by a magnitude influenced by the structure. Differently, the values of Young's modulus remained comparable to that of PMMA.