TITLE:
Nitroxide-Mediated Photo-Controlled/Living Radical Polymerization of Methacrylic Acid
AUTHORS:
Eri Yoshida
KEYWORDS:
Photo-Controlled/Living Radical Polymerization; Nitroxide-Mediated Polymerization; Methacrylic Acid; 4-Methoxy-2, 2, 6, 6-Tetramethylpiperidine-1-Oxyl; (4-Tert-butylphenyl)diphenylsulfonium Triflate; Molecular Weight Control
JOURNAL NAME:
Open Journal of Polymer Chemistry,
Vol.3 No.1,
February
28,
2013
ABSTRACT: The photo-controlled/living radical polymerization of methacrylic acid (MAA) was performed at room temperature by irradiation with a high-pressure mercury lamp using azo initiators and 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator in the presence of (4-tert-butylphenyl)diphenylsulfonium triflate (tBuS) as the accelerator. Whereas the bulk polymerization yielded polymers with a bimodal molecular weight distribution in both the absence and presence of tBuS, the solution polymerization in methanol produced unimodal polymers with the molecular weight distribution of 2.0 - 2.3 in the presence of tBuS. The molecular weight distribution of the resulting poly (MAA) decreased with an in- crease in tBuS. The dilution of the monomer concentration also reduced the molecular weight distribution. The use of the initiator with a low 10-h half-life temperature also effectively controlled the molecular weight. The livingness of the polymerization was confirmed by obtaining linear increases in the first-order conversion versus time, the molecular weight versus the conversion, and the molecular weight versus the reciprocal of the initiator concentration.