Poly comonomer ratio

In addition, data on the size, shape and solvation of the polymer particles in aqueous solutions at temperatures below and above the transition phenomena registered by HS-DSC have been obtained [42]. Table 2 shows the results of capillary viscometry and light scattering experiments for the fractions p and s of poly(NVCl-co-NVIAz) synthesized at 65 °C from the feed with the initial molar comonomer ratio equal to 85 15. Since fraction p precipitates from the aqueous solution at temperatures > 34 °C, its intrinsic viscosity can be determined only at 20 °C, whereas for the fraction s such measurements were possible above and below the temperatures of the HS-DSC-registered conformational transition. 

It was shown that the final copolymers synthesized at 30 °C from the feeds with molar comonomer ratios of 95 5 and 90 10 contained 4.8 and 11.4 mol % of NVP units and had molecular weights 4.2 x 106 and 7.9 x 106, respectively. Poly(NiPAAm-co-NVP)s that formed in the course of precipita-... 

Suspension grade poly(vinyl chloride) Tarwinyl S-60, having the Fikentscher number K = 60.3 and M = 1.02x10, as well as polymethacrylates prepared in our laboratory by suspension polymerization were used throughout this study. The polymethacrylates used were PMMA, PBMA and copolymers MMA/BMA the respective comonomer ratios were 50/50 and 30/70. Molecular weights of all polymethacrylates were similar (M = 9x10 ). 

Fig. 3 Thermonephelometry curves of aqueous solutions of the o-, p- and s-fractions of poly(NVCl-co-NVIAz) synthesized at 65 °C from the feeds with initial molar ratios of comonomers equal to a 85 15 and b 90 10 (the data from [27])... 

The exclusive formation of the block copolymer has been confirmed by selective fractionation, NMR spectroscopy, and SEC analysis. For instance, the copolymerization of eCL and 6VL has been followed by SEC. Figure 2 compares the SEC chromatograms of the first PCL block and the final poly(eCL-h-6VL) diblock copolymer. The molecular weight of the macroinitiator is shifted towards higher values in close agreement with the theoretical value expected from the comonomer-to-Al(OzPr)3 molar ratio, and the MWD remains very narrow during the copolymerization process (PDI=1.10). 

CALB-catalyzed copolymerization of CL with 11-mercaptoundecanoic acid (1IMU) leads to the formation of poly(ester-c6>-thioester)s having a Mn of 13.7 kDa (PDI 1.6) after precipitation [30] (Fig. 11). The amount of incorporated IIMU (8.7mol%) was slightly less than the feed ratio (10mol%). Similar results were obtained when using 3-mercaptopropionic acid (3MP) as a comonomer (Mn 14.3 kDa, PDI 1.4). CALB-catalyzed transesterification of pCL with either 1 IMU or 3MP resulted in similar H-NMR and C-NMR spectra as the direct copolymerization of the two monomers, showing that continuous transesterification plays an important role in the microstructure of the polymer [30]. 

Polymerization Results. A batch polymerization of MMA-MAA comonomer was analyzed for the determination of the reactivity ratios of the two monomers. The change in the ratio of the copolymer composition determined by GC was plotted against conversion as shown in Figure 1. Similarly, the calculated curves for some assumed reactivity ratios are also shown in the same Figure. The optimum values of the reactivity ratio for the emulsion poly-... 

The crystallinity, brittleness, and melting point of poly(L-LA) can be decreased by incorporation of comonomer units such as l,5-dioxepan-2-one (DXO). The large difference in reactivity ratio between the DXO and the lactides leads to a microstructure with a more block-like nature than is expected from a... 

The relative reactivity of the macromonomer in copolymerization with a common comonomer, A, can be assessed by l/rA=kAB/kAA> i-e-> the rate constant of propagation of macromonomer B relative to that of the monomer A toward a common poly-A radical. In summarizing a number of monomer reactivity ratios in solution copolymerization systems reported so far [3,31,40], it appears reasonable to say that the reactivities of macromonomers are similar to those of the corresponding small monomers, i.e., they are largely determined by the nature of their polymerizing end-group, i.e., essentially by their chemical reactivity. 

Narrow distribution in the backbone length as well as in the chemical composition or the branch frequency may be expected from a living-type copolymerization between a macromonomer and a comonomer provided the reactivity ratios are close to unity. This appears to have been accomplished to some extent with anionic copolymerizations with MMA of methacrylate-ended PMMA, 29, and poly(dimethylsiloxane) macromonomers, 30, which were prepared by living GTP and anionic polymerization, respectively [50,51]. Recent application [8] of nitroxide (TEMPO)-mediated living free radical process to copolymerizations of styrene with some macromonomers such as PE-acrylate, la, PEO-methacr-ylate, 27b, polylactide-methacrylate, 28, and poly(e-caprolactone)-methacrylate, 31, may be a promising approach to this end. 

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