Solution copolymers

PVC/PVA copolymer solutions Polyvinyl chloride/polyvinyl acetate copolymers can be readily dissolved in blends of aromatic hydrocarbon,... 

The presence of flexible PEO and PPO blocks increases the viscosities of block copolymer solutions, this tendency is manifesting itself the stronger the greater is the PEO and PPO content in block copolymers. 

Hashimoto T., Shibayama M., and Kawai H., Ordered structure in block copolymer solution. 4. Scaling rules on size of fluctuations with block molecular weight, concentration temperature in segregation and homogeneous regimes. Macromolecules, 16, 1093, 1983. 

Linse, P Mahnsten, M, Temperature-Dependent MiceUization in Aqueous Block Copolymer Solutions, Macromolecules 25, 5434, 1992. 

Viscosimetric studies of organotin copolymer solutions allow the changes in the shape of the macromolecules to be followed as a function of the electrostatic charge. From the plot of the intrinsic viscosity of copolymers in DMFA solution against the degree of dilution it is seen that increasing dilution results in a rise of viscosity, probably due to an extension of macromolecular chains accompanied by conformational transformations. Naturally, this rise in viscosity with dilution cannot proceed infinitely since a coiled chain cannot be extended more than a completely extended chain conformation, due to intramolecular repulsion. 

The observed anomaly in the viscous properties of dilute organotin copolymer solutions seems to be attributable to the existence of both intra- and intermolecular associates,due to coordination interactions between SnR3 and C=0 fragments of side groups. 

Predictions of the Evolution with Time of the Viscosity of Acrylamine—Acrylic Acid Copolymer Solutions... 

Figure 7. Effect of sodium chloride concentration on the viscosity of hydrolyzed poly(starch g-(2 propenamide)) copolymer solutions.

Effective viscosity as a function of shear rate for 0.15 g/dL of copolymer 5 in distilled water is given in Figure 15 The Ostwald-DeWaele exponent for copolymer solutions is greater than that of matching hydrolyzed copolymer solutions at a given concentration. Thus, copolymer molecules are less compactable in solution than are their hydrolyzed derivatives, and pseudoplasticity of polymer solutions increases upon hydrolysis. 

Viscosity of copolymer solutions decreases by, at most, 3 percent when electrolyte concentration changes from 0 to 0.342 M sodium chloride or 2.45 x 10 M calcium chloride. Viscosity of hydrolyzed polymer solutions decreases exponentially with increasing electrolyte concentration in water. 

Figure 67 shows Q QVQ2 vs. Q for both systems. As expected from Eqs. (142) and (143) their behavior is completely different. One can see that a pronounced divergency occurs at small Q-values in the semi-dilute block copolymer solution. If Qi(Q)/Q2 is analyzed in terms of a generalized mobility ji(Q) [see Eq. (94)], Fig. 68 results from the different concentrations of the diblock copolymer solution. Q(Q) varies both with Q and with c. In particular, the Q-dependence is indicative of the non-local character of the mobility and incompatible with the assumption of a pure Rouse type of dynamics. The... 

Prior to the addition of the silica precursor (TEOS), the acidic copolymer solution appears transparent and the SANS data shows that the copolymer forms spherical micelles of size 7.1 nm (figure 1-a). After the addition of TEOS, the solution becomes immediately turbid. Most probably, it is because TEOS is hydrophobic and forms an emulsion droplets under stirring when added to the solution [3], Then, the opacity increases with time (figure 1-b), until a thick white precipitate forms after about 23 minutes (figure 1-c). 

Fig. 10a Average hydrodynamic radii ((Rh)agg) and b weight-average molar mass ((Mw)agg) of the aggregates in aqueous block copolymer solutions at different polymer concentrations (c given in moles of PNIPAM blocks) at 45 °C a NE-A, b NE-B, c NE-C, d NE-1, e NE-2, and/ NE-3. (Reprinted with permission from Ref. [169] copyright 2002 American Chemical Society)... 

The plots of h/h vs. copolymer concentration also reveal differences in the micropolarity of the hydrophobic domains created upon association of the various copolymers in water. A qualitative assessment of this property is given by the h/h value determined in the copolymer solutions of highest concentration when the plateau value is attained (Fig. 25). This value depended significantly on the grafting level the solution of the most densely grafted copolymer yielded the lowest h/h value (1.40) and the pure homopolymer the highest. In all cases, this value is higher than the value (1.20) recorded for micellar solutions of the macromonomer. It can be concluded... 

Keywords Chemical synthesis Heterogeneous blockiness Physicochemical studies Protein-like copolymers Solution behaviour... 

One such property, as has been demonstrated (see [26]), is the change in partial heat capacity of the copolymer solution upon the heat-induced conformational transition of macromolecules. Such a change was detected by high-sensitivity differential scanning calorimetry (HS-DCS). The DSC data for the NVCl/NVIAz-copolymers synthesized at initial comonomer ratios of 85 15 and 90 10 (mole/mole) are given as thermograms in Fig. 4. 

A copolymer is a macromolecule comprising two chemically distinct types of monometer unit, A and B, whilst a terpolymer is composed of units A, B and C. The analytically determined composition of a copolymer is expressed as the weight fractions WA and WB of its constituents. For LS studies on a copolymer solution it is necessary to know the value of the specific refractive index increment v, which can be either measured or calculated from ... 

The theory of LS from copolymer solutions was pioneered by Stockmayer et al. and later by Bushuk and Benoit, subsequent developments being due to Benoit, Inagaki et al Molecular weight determination constitutes only a part of the most recent review of the field by Benoit and Froelich149 ... 

Examples have been reported for several systems161,166 some results are listed in Table 16. In summary, polymer mixtures can be treated as copolymers of extreme heterogeneity in chemical composition. Under suitable conditions the techniques used in analysing data of LS from copolymer solutions can be applied to yield with good accuracy the molecular weights of components of the binary polymer mixtures. 

Research Scientist / Sr. Scientific Manager, Team lead in Research Development after doctorate degree from Premium Indian Institute of technology, India and more than 5 years relevant industrial experience in R D from bench Scale to Pilot scale till plant scale in (Thermoplastic/ Thermoplastic elastomer) elastomers / SBR (Styrene butadiene copolymer)- Solution,... 

For example, the (salen)Co(III) catalysts depicted in Figs. 11 and 12 have been isolated with concomitant purified copolymer by filtration of the polymerization solution through a short pad of silica gel (230-400 mesh) resulting in the metal catalyst being trapped on the pad and the copolymer solution eluted [33]. The (salen)Co(III) catalyst was recovered from the silica gel pad upon solubilization with a methanol solution of NaBF4. In this manner, the separated catalyst could be reused without significant loss in catalytic activity and the copolymer isolated with a metal residue of only 1-2 ppm. 

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