Enhancement of Isotacticity in Bulk Radical Polymerization of Poly(methyl methacrylate) under Strong Gravity Field

Abstract

KEY WORDSPoly(Methyl Methacrylate)(PMMA) / Centrifugation / Strong Gravity Field / Tacticity / 1 H NMR spectroscopy / Isotacticity / Stereoregular polymers are one of the most important materials in industry due to its thermostability, stiffness and chemical resistance. Stereoregular polymers have been prepared by polymerization with metal catalysts such as Ziegler-Natta catalysts. They have been extensively studied by the polymerization with Grignard reagents, alkylaluminum and alkyllithium. 1 On the other hand, control of stereoregularity without metal catalysts should be valuable. For this purpose, it has been reported the polymerizations of methacrylates having bulky side chains. 2 However, this idea provides limitation of chemical structures in monomers and then may be less applicable to extend.In this study, we aim to increase stereoregularity in free radical bulk polymerization of general-purpose monomers without special metal catalyst. Therefore, we focused on the polymerization under strong gravity field over 10 5 g although there has been a few reports under gravity field of 10 4 g level 3 and their research aims are not related to stereoregularity. 3,4 Fortunately, one of the authors has established the sedimentation theory under mega gravity field 5 and also developed the centrifugal apparatus generated over 10 6 g. 6 This gravity field can induce the sedimentation of metal atoms in solid-solution system alloy. 7 If monomers have a deviated center of gravity and are exposed to strong gravity field, the polymerization may proceed with molecular orientation of the monomers. In this study, methyl methacrylate was used as a monomer. The tacticity of the resultant poly(methyl methacrylate) (PMMA) was measured by 1 H NMR spectroscopy. † To whom correspondence should be addressed.

Sedimentation of Substitutional Solute Atoms in Condensed Matter: New Type of Diffusion

“…The one-dimensional displacement of atoms may also affect the ordering and orientation of atoms or molecules, crystal growth. In fact, we observed the crystal growth in alloys [11,12,14] and the increase of orientation on an organic material [15].…”