Radical polymerization of various alkyl methacrylates in liquid crystalline solvents

Abstract

The polymerization of methacrylates of methyl, ethyl, butyl, hexyl, octyl, dodecyl, and octadecyl alcohols was studied with 2,2′‐azobisisobutyronitrile in the smectic, nematic, cholesteric, and isotropic liquid phases at 50–75°C. N‐(4‐Methoxyphenylmethylene)phenylamine, N‐(4‐ethoxyphenyl‐methylene)‐4‐butylphenylamine, cholesteryl octadecanoate, and benzene were used as the solvents. The viscosities of the polymers were enhanced in the mesomorphic solvents. The polymer was converted to the corresponding poly(methyl methacrylate) through hydrolysis and esterification. Tacticities of the resultant poly(methyl methacrylates) were determined by nuclear magnetic resonance spectroscopy. The isotacticities of the polymers obtained in the smectic and the nematic phases were basically the same and appeared to be larger than those of the polymers in the cholesteric and isotropic liquid states. The polymerization of the methacrylates of butyl and longer‐chain alcohols deviated from Bernoullian statistics and gave polymers more isotactic than those of methyl and ethyl methacrylates.

Stereospecific Living Radical Polymerization: Dual Control of Chain Length and Tacticity for Precision Polymer Synthesis

“…Various alkyl methacrylates were also polymerized in liquid crystalline solvents with nematic, smectic, and cholesteric phases using N-(4-methoxyphenylmethylene)phenylamine , N-(4-ethoxyphenylmethylene)-4-butylphenylamine (SS-15), and cholesteryl octadecanoate (SS-16). 370 While no significant effects were observed for the MMA polymerization, methacrylates with aliphatic alkyl chains underwent slightly isotactic specific polymerizations in the mesomorphic phase, in which the polymers formed in the smectic and nematic phases had a higher isotacticity than those in the cholesteric one. For example, n-octyl methacrylate produced polymers with the highest meso contents in the smectic phase of SS-16 (mm/mr/rr ) 31/29/40).…”

Effects of Unsaturated Metal Sites on Radical Vinyl Polymerization in Coordination Nanochannels

“…To study the details of the polymerization mechanism, the Coleman − Fox parameter was calculated from the tacticity values of the PMMA normalρ = 2 false[ italicm false] false[ italicr false] / false[ italicmr false] The values of ρ for PMMA obtained in our experiments were found to be almost equal to (Σ P ) −1 (Table ), suggesting that the polymerization of MMA in 1 can be applied to first-order Markov statistics. , Thus, a penultimate effect might be dominant in the stereoregulation of the polymerization in the nanochannels of 1 .…”

“…However, the observed pentad values could provide more accurate triad distributions, thus we estimated the following parameters using the calculated triad fractions: P m / r = 1 − P m / m = [ mr ] / ( 2 [ mm ] + [ mr ] ) P italicr / italicm = 1 − P italicr / italicr = false[ italicmr false] / false( 2 false[ italicrr false] + false[ italicmr false] false) where P m / r is the probability that a racemo addition follows a meso addition, P r / m is the probability that a meso addition follows a racemo addition. In case of our polymerization in 1Tb , the sum of P m / r and P r / m (Σ P ) gave 1.034, showing a slight deviation from Bernoullian sequence distribution. , We also determined Σ P using 1 H NMR spectra of PMMA prepared in the other 1 , where the values of Σ P were not close to unity (Table ). Therefore, in our polymerization system, it is unlikely that chain-end control is responsible for the resulting stereostructure of PMMA.…”

“…In case of our polymerization in 1Tb, the sum of P m/r and P r/m (ΣP) gave 1.034, showing a slight deviation from Bernoullian sequence distribution. 44,45 We also determined ΣP using 1 H NMR spectra of PMMA prepared in the other 1, where the values of ΣP were not close to unity (Table 1). Therefore, in our polymerization system, it is unlikely that chain-end control is responsible for the resulting stereostructure of PMMA.…”

“…The values of F for PMMA obtained in our experiments were found to be almost equal to (ΣP) À1 (Table 1), suggesting that the polymerization of MMA in 1 can be applied to first-order Markov statistics. 44,45 Thus, a penultimate effect might be dominant in the stereoregulation of the polymerization in the nanochannels of 1.…”