Composition of monomer

Gel Permeation Chromatography (CPC) is often the source of molecular wei t averages used in polymerization kinetic modelling Q.,2). Kinetic models also r uire measurement of molecular weight distribution, conversion to polymer, composition of monomers in a copolymerization rea tion mixture, copolymer composition distribution, and sequence length distribution. The GPC chromatogram often reflects these properties (3,. ... 

A user-friendly computer program has been developed (A.S.Yakovlev, S.LKuch-anov Copolymerization for Windows ) which makes it possible at any values of conversion to calculate for m=2-6 along with the composition of monomer mixture x, such statistical characteristics as instantaneous X and average (x j copolymer composition as well as the fractions (P Uk of sequences Uk with k=2-4 and... 

It was in article [52] where the main reason responsible for the above-mentioned peculiarities was explicitly formulated and substantiated. Its authors related these peculiarities with partitioning of monomer molecules between the bulk of a reaction mixture and the domain of a growing polymer radical. This phenomenon induced by preferential sorption of one of the monomers in such a domain is known as the bootstrap effect. This term was introduced by Harwood [53], because when growing a polymer radical can control under certain conditions its own microenvironment. This original concept enabled him to interpret many interesting features peculiar to this phenomenon. Particularly, he managed to qualitatively explain the similarity of the sequence distribution in copolymerization products of the same composition prepared in different solvents under noticeable discrepancies in composition of monomer mixtures. 

Fig. 8 Dependencies on conversion p of monomer mixture composition x (a), instantaneous X (b) and average X) (c) copolymer composition as well as dispersion a2 (d) of the composition distribution calculated at different values of the initial compositions of monomers x°. The calculations have been carried out at values of parameters a and a2 = 1 - fli (Eq. 100) equal to 0.3 and 0.7, respectively... 

The chiral molar composition dependences of the peak wavelengths in the UV and FL spectra in 44 and 45 are shown in Figure 4.32. As the molar composition of monomer unit with chiral groups changes from 0.00 to 0.50, these... 

Figure 432 UV and FL peak wavelength dependence on molar composition of monomer unit with chiral groups in copolymers 44 and 45 in THF at 23-25°C.

The monomers are randomly distributed in the Polymer chain in most of cases but in case of copolymerisation of styrene and maleic anhydride, there is perfect alternate arrangement of monomers in the chain regardless of initial composition of monomers. 

Figure 5.4. Kellen-Ttidos plot for calculation of reactivity ratios from composition of monomer mixture, R, and composition of copolymer, E Copolymerization of methacrylic acid with methyl methacrylate in the presence of PEG 20,000. Reprinted from S.PolowinskijEnr.PoZym.t/., 19,679 (1983) with kind permission from Elsevier Science Ltd.

For copolymerization of AN and styrene, the composition of polymers is determined by the composition of monomers participating in... 

Figure 4. Experimental relative composition of monomer mixture in whole emulsion (Xm) and in particles (Xp)...

With block copolymers, compositional analysis by thermal FFF is complicated by the fact that thermal diffusion is dominated by the composition of monomer units in the outer free-draining region of the polymer-solvent sphere. When block copolymers are dissolved in a selective solvent, which is a solvent that solvates certain blocks better than others, the more soluble blocks tend to segregate to the outer regions of the... 

It is expected that plasma characteristics are different from position to position in a flow reactor. Thus, densities of active species and/or composition of monomer and argon differ with position as a result of competition between diffusion and consumption. Variation of Tg and ng with position of the probe under typical conditions is shown in Table 3. The change is significant in most cases. It explains the fact that a polymer film with excellent properties can be obtained only in a limited region of the reactor under fixed conditions. Tg and n showed their maximum at the rf coll position and decreased monotonlcally along the downstream direction. The pattern of decrease depends on the reaction conditions. 

Since standard compounds may not be readily available, control of these parameters and validation of the analytical procedure can be very difficult. Usually, agreement with the independently determined average DS, the absence of side products, and high recovery of material (determined by addition of an internal standard) are used for control. GLC/FID allows calculation of the relative molar composition of monomers by correcting their peak areas according to the ECR concept, as already mentioned. "- ... 

The chemical composition of monomers and the properties conferred on monomers as a result of their chemical composition... 

We have discussed chemical bonding, monomer functionality, and polymerization mechanisms in previous sections. Our attention now focuses on the chemical composition of monomers. 

Fig. 18 Schematic composition of monomer used in ELP design described in text. The scheme shows the different functional domains of monomer, which can be easily identified with their corresponding peptide sequences...

Acrylic copolymers may be internally plasticized by the selection of an appropriate composition of monomers which give the copolymer the required glass transition temperature. 

Composition of monomer solution Dose (Mrad) Weight increase (%) Quaternized Flux" (gfd-mil) Salt" r j- (%)... 

---