Tacticity of poly

Table 8.2 Effect of Solvent on Tacticity of Poly(alkyl methacrylate) at -40 °C94...

Table 8.3 Effect of Amines on Tacticity of Poly(methacrylic acid) at 60 DC90...

Further confirmation of the structure and tacticity of poly/5-methyl-l,4-hexadiene)was obtained from X-ray diffraction and u-NMR data of its hydrogenated polymer (Scheme 2). The hydrogenated polymer sample showed a highly crystalline pattern (Figure 7), with diffraction spots that were well defined. This pattern was identical to that of isotactic poly(5-methyl-l-hexene) as reported in the literature (26) (measured identity period, 6.2 A lit., 6.33 A). 

Figure 2. Triad tacticity of poly (MMA-co-TrMA) obtained with BuLi in THF at —78°C.

The tacticity of poly(methyl methacrylate) (PMMA) polymers is particularly amenable to characterization by proton NMR spectroscopy. 

Figure 3. Effect of catalyst, solvent, and temperature on the tacticity of poly (methyl methacrylate)...

We have been concerned with the precision and accuracy of NMR data of polymers since we first started NMR studies on polymers.1-4 Using continuous-wave (CW) spectrometers, the effects of measurement conditions including temperature, sample concentration and radiofrequency (rf) field strength, were examined using several polymer and copolymer samples. Since our research group have been deeply involved in stereospecific polymerization of methacrylates, one of the main concerns about NMR measurement was the precision of tacticity determination by NMR. The errors in determining the tacticity of poly(methyl methacrylate) (PMMA) and those in the results of polymerization of methyl methacrylate (MMA) by radical and anionic initiators were examined and found to be satisfactorily small.4 Although there... 

Schrbder et al.81 studied the effect of solvent on the tacticity of poly(meth-acrylic acid). Unlike the methyl ester, the structure of poly(methacrylic acid) prepared at 60 °C was found to depend on the solvent, changing from 70% syndi-otactic in xylene to 91-92% syndiotactic in polar solvents such as tetrahydrofuran and hexamethylphosphoric triamide. 

The former pointed out a stereocontrol by hydrogen bond in the transition state as the cause of the solvent effect. Recently, Yamamoto et al.90 investigated the solvent effect on the tacticity of poly (vinyl acetate) by 13C-NMR in various solvents, indicating that there was no solvent effect on the stereoregularity. 

The Effect of Mixed Solvent Composition on the Tacticity of Poly(methyl methacrylate) Initiated by /i-Butyl Lithium at 243 K... 

Other homopolytners that are investigated in terms of stereochemical configuration are, for example polystyrene (mainly by means of carbon-13 NMR) and polyfcr-methyl stymie) [125]. More recoidy, the tacticity of poly(n-butyl methacrylate) has beoi studied by high-resolution carbon-13 and proton NMR... 

The Tg of pdymethacrylates increases as the bulkiness of side chain increases and its flexibility decreases. Tg also correlates with the tacticity of poly(oe-substituted acrylate) and is lower for isotactic pdymer than for syndiotactic one. Good correlation was obtdned between the dyad tacticity and Tg. Therefore, the Tg value of 100 % isotactic or 100 % Syndiotactic polymer could be determined by the extrapolation of observed values even if it has not been prepared. The Tg for purely syndiotactic pdy(methyl methacrylate) thus obtained is... 

Yoshie, N., Azuma, Y., Sakurai, M., and Inoue, Y., 1995, Crystallization and compatibility of poly(vinyl alcohol)/poly(3-hydroxybutyrate) blends influence of blend composition and tacticity of poly(vinyl alcohol). Appl. Polym. Sci. 56 17-24. 

Ikqima, T., Yoshie, N., and Inoue, Y., 1996, Infrared analysis on blends of poly(3-hydroxybutyric acid) and stereoregular poly(vinyI alcohol) influence of tacticity of poly(vinyl alcohol) on crystallization of poly(3-hydroxybutyric acid). Macromol. Chem. Phys. 197 869-880. 

RAY Ray, B., Okamoto, Y., Kamigito, M., Sawamoto, M., Seno, K., Kanaoka, S., and Aoshima, S., Effect of tacticity of poly(A-isopropylacrylamide) on the phase separation temperatnre of its aqueous solutions, Polym. J., 37, 234, 2005. 

PAA can be prepared using bulk polymerization, aqueous polymerization, nonaqueous polymerization, inverse phase emulsion and suspension polymerization. The precise structure of the resulting PAA chain is dependent upon many factors including the polymerization process and conditions. The tacticity of poly(methacrylic acid), PMA, has been studied using NMR spectroscopy (6). For polymerization of methacrylic acid in methyl ethyl ketone at 60 C gives a polymer with 57% syndiotactic triads. Polymerization at low temperatures gives a more syndiotactic product (6) as does polymerization at high pH (7). 

Molecular weight and tacticity of poly(methyl methaciylate) formed by RAFT polymerization of methacryiic acid and salts. 

TACTICITY OF POLY(anti-7-methylNBE) AND POLY(7-methylNBD)... 

Le Borgne, A. Spassky, N. Jun, C. L. Momtaz, A. Carbon-13 NMR study of the tacticity of poly(propylene oxide)s prepared by polymerization with a, y, 8-tetraphenylporphyrin/AlEt2Cl as initiator system An example of first-order Markovian statistics in ring-opening polymerization. Makmmol. Chem. 1988,189, 637-650. 

Subsequent work by D. Braun and collaborators dealt with the effect of solvent polarity and countercation on the tacticity of poly(methyl methacrylate) (PMMA) initiated with various organo alkali metal compounds. By using proton NMR analysis they concluded that polar solvents and alkyl lithium initiators favored syndiotactic configurate on( ) while non-polar solvents favored isotactic piacement( )." ... 

Quinting and Cai [62] carried out high-resolution C-NMR and proton NMR measurements to determine the tacticity of poly(n-butyl methacrylate) (PBMA) with particular focus on the peak assignments for the n-butyl side chain. Free-radical and anionic PBMA were examined, with the former being predominantly syndiotactic and the latter isotactic. Proton NMR resonances for the n-alkyl chain of these polyacrylics show a combination of effects from configurational sensitivity and homonuclear scalar interactions. A combination of J-resolved proton NMR and proton- C-heteronuclear correlated 2D-NMR spectra was used to characterise the long-range chemical shift effects due to tacticity. 

The triad tacticities of poly(ethyl methacrylate)s were measured by peak eliminated Fourier transform NMR method(6) In toluene-dg at 100 C. The H-NMR spectra were taken on a JNM-FX-IOO(JEOL) spectrometer at lOOMHz. 

Lemieux, E., Prud homme, R. E., Eorte, R., Jerome, R., Teyssie, P. Influence of the tacticity of poly(methyl methacrylate) on its miscibility with chlorinated polymers. Macromolecules, 21, 2148-2154 (1988). 

Table 8.7. Influence of the temperature of free radical polymerizations on the tacticity of poly(methyl...

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