Methyl copolymer

Methylation of hydrolyzed or methanolized copolymers. One gram samples of hydrolyzed or methanolized copolymers were suspended or dissolved in dry benzene and the mixtures were treated with diazomethane until methylation was complete. This was indicated by the complete dissolution of the copolymers and by the presence of the yellow color of diazomethane in the reaction mixtures for 8 hrs. The reaction mixtures were poured into methanol to precipitate the products, which were reprecipitated twice from benzene solution into methanol before being dried in vacuo. Completely methylated copolymers were soluble in CCli, but copolymers containing very small amounts of acid units were not. This simple test was employed routinely to ensure the completeness of methylation. The 1H-NMR spectra of the copolymers in C D6 solution were examined for the presence of carboxylic acid proton resonances at 5=11.5 ppm as an additional criterion for the completeness of methylation. 

Changes in the polymer concentration had no significant effect on the fluorescence behavior therefore, the transition was an intramolecular rather than an intermolecular phenomenon. In contrast to the butyl copolymer, the dansylated methyl copolymer, whose fluorescence is also shown in Figure 3, undergoes no transition its fluorescence is essentially constant over the whole ionization range. The low value is characteristic of the aqueous environment that the probe experiences in the random coil conformation. 

Figure 3. Dependence ofF 520, the fluorescence emitted at 520 nm hy dansylated copolymers, on the degree of deprotonation, a. Key 0, O, , butyl copolymer in water, 0,2 M NaCl, and 0.5 M NaCl, respectively , methyl copolymer in water. Adapted from ref. 18. Copyright 1975 American Chemical Society.)...

SmM Mg concentration. The chemical shift of the central peak appears to be equivalent to that of the starting material, and this third component might have been present in the non-methylated copolymer but obscured by line broadening (XS) although it was apparently absent in the other material in the Z-form... 

Random Poly(methyl copolymer methacrylate) Alternating —... 

The results of the application of this method to potentiometric titration data obtained for the butyl copolymer in 0.2 M LiCl is illustrated in Figure 6, where the prc ess of the species population distribution is followed as the polyacid passes through the conformational transition. 2 Over the range of a in which the transition is known to occur, the distribution functions are bimodal, with a deep minimum at i = 4. One may assign the species with i < 4 to the compact conformation and those with i > 4 to the random coil conformation. In contrast, only single-peaked distribution functions were obtained for the methyl copolymer, which is known not to undei o a conformational transition. The method thus clearly establishes the two-state nature of the conformational transition of the butyl copolymer. 

Alternating copolymers ( interpolymers ) of maleic anhydride and alkyl vinyl ethers are prepared by free radical polymerization in solvent, non-solvent or bulk media Products prepared from ethyl-, butyl-, hexyl-, and octyl-, and decyl- vinyl ethers are described in Table I. The decyl-copolymer was prepared by Dr A. W. Schultz. A methyl-copolymer ( Gantrez AN General Aniline and Film Corp.), not described in Table I, was included in some studies. Molecular weight estimates were... 

Copolymers consisting of (3-CD and EPI were used for the nucleophilic substitution of halogeno-alkanes [20]. The ratio between CD and EPI varied from 3 to 10. Methylated copolymers were also synthesized from the previous ones by methylation. The nucleophilic substitution of three bromo-alkanes was considered as a model reaction using sodium iodide as nucleophile in the presence of P-CD alone or with the synthesized CD-EPl copolymers (Scheme 2.6). 

Other common cross-fractionation techniques are SSF/A-Tref and SSF/ P-Tref [41,42]. In these techniques, polymers are first fractionated using SSF and the fractions are then further fractionated according to chain crystallizabilities using A-Tref or P-Tref. When P-Tref is used, further determination of comonomer content by C NMR or FTIR spectroscopy is required. Figures 19 and 20 show 3D and contour plots of bivariate distributions of molecular weight and comonomer composition obtained by SSF/P-Tref crossfractionation for an ethylene/l-pentene-4-methyl copolymer [42]. Comparing the contour plot with the equivalent contour plot of a LDPE sample (Fig. 21), one clearly notices significant differences between the bivariate distributions of these two samples. 

Variations in the Deprotonation-Substitution Reactions. As discussed in the previous paper in this volume, the preparation of copolymers with combinations of alkyl and aryl groups attached to the backbone by P-C bonds is readily achieved by the condensation polymerization of appropriate mixtures of N-silyl hosphoranimines. The highly methylated copolymers 15 are of particuhiar interest in terms of deprotonation-substitution reactions for several reasons. First, with even a low proportion of phen d groups, these copolymers remain soluble in THF, a solvent suitable for deprotonation-substitution reactions. Second, the of the copolymers are significantly lower than... 

---