Stereospecific Radical Polymerization of N-Methyl Methacrylamide

Abstract

N-Methyl methacrylamide (N-MMAm) was polymerized using radical initiators under various conditions. The triad tacticity of the obtained polymers was determined by 100 MHz 13 C NMR. The polymers were rich in syndiotactic configuration. At a given temperature, the syndiotacticity increased with an increase in solvent polarity. This solvent effect may have connection with the hydrogen bonding interaction among solvent, monomer, and growing species. The fraction of rr triad increased with decreasing polymerization temperature in all solvents. Monomer concentration also affected the stereochemistry of the polymerization. By optimizing conditions, a high rr specificity (rr =95%) was achieved. Thermal property of the poly(N-MMAm)s with different tacticities was studied by DSC.KEY WORDS Radical Polymerization/ Tacticity / Stereochemistry / Solvent Effect/ Syndiotacticity / Methacrylamides /

Controlled/Living Radical Polymerization of Methacrylic Monomers in the Presence of Lewis Acids: Influence on Tacticity

“…As reported by Okamoto et al, [28] the triad tacticity of PMMAM can be estimated from the a-methyl protons region (0.5-1.2 ppm) of the 1 H NMR spectra. In the absence of Lewis acids, the polymer formed was predominantly syndiotactic (rr > mm, Table 1, Entry 1).…”

Syndiotactic- and heterotactic-specific radical polymerization of N-n-propylmethacrylamide complexed with alkali metal ions

“…[24][25][26][27][28] For instance, poly(N-methylmethacrylamide) [ poly(NMMAAm)] with rr triad = 95% was prepared in (CF 3 ) 2 CHOH at −78°C. 24 Poly(N-isopropylmethacrylamide) [ poly(NIPMAAm)] with mm triad = 67% was prepared in methanol at −20°C in the presence of Yb(OTf ) 3 . 25,26 Radical polymerization of bulky methacrylamides such as N-triphenylmethylmethacrylamide gave nearly 100% isotactic polymers.…”

Isotactic‐specific radical polymerization of methacrylamides in the presence of Lewis acids

“…Therefore, stereocontrol during the polymerizations of methacrylamides has not yet been studied in detail. [13][14][15][16][17][18] Although we reported the synthesis of syndiotactic poly(N-methylmethacrylamide) by radical polymerization, 19 the isotactic polymer has not yet been prepared to the best of our knowledge. In this article, we report the isotactic-specific radical polymerization of N-monosubstituted methacrylamides, N-methylmethacrylamide (MMAM) and N-isopropylmethacrylamide (IPMAM), with Lewis acids, such as triflates of Sc, Yb, Y, Tm, and Lu: EXPERIMENTAL MMAM (TCI) was purified by distillation under reduced pressure.…”

“…1). 19 The polymerization in the absence of Lewis acids gave a syndiotactic polymer (entry 1), whereas a significant increase in the isotacticity was observed for the polymers prepared with a catalytic amount (10 mol %) of Yb(OTf) 3 , Y(OTf) 3 , Tm(OTf) 3 , and Lu(OTf) 3 (entries 3-6). Sc(OTf) 3 and YbCl 3 were less effective for stereocontrol (entries 2 and 7), and little influence was observed for MgBr 2 , which showed an increasing isotacticity effect for the polymerization of methyl methacrylate (MMA).…”