Interface Polymerization in a Polymer Micelle: An NMR Study of the Radical Polymerization of Methyl Methacrylate at the Core−Shell Interface of Polystyrene-block-poly(methacrylic acid) Micelles

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Systems containing poly(styrene)-block-poly(methacrylic acid) micelles (1.67 g/L), methyl methacrylate (1.88−3.76 g/L), and initiator (polymerization) or inhibitor (pure solubilization) in D2O buffer solution were studied by 1H NMR. The proton NMR signals of MMA dissolved in the micellar system have the same chemical shifts as those in the corresponding D2O buffer solution but exhibit a characteristically broadened and asymmetric shape. Separate signals with different chemical shifts and signal shapes were observed for MMA absorbed into the poly(styrene) core. From the shape analysis of the signals of the water-dissolved MMA in the micellar system, it can be deduced that the monomer is almost exclusively accumulated near the core−shell interface. Its radial distribution can be approximated by a Gaussian function with the maximum at the core radius R and half-width b of 1.65R and 1.93R for the MMA concentrations 2 and 4 g/L, respectively. An increase in temperature from 295 to 330 K leads to a faster self-...