Search results for "Vinyl polymer"
showing 5 items of 5 documents
Extension of GPC Techniques
1971
Abstract Most of the common GPC gels exhibit pore sizes which are too small to separate very extended molecules, e.g., native cellulose in solution. Several gel types were tested with vinyl polymers of molecular weights up to 107 and with cellulose nitrate. Large pore size Styragel with acetone as solvent proved to be the most favorable gel system yielding effective separations for polymers with coil diameters in solution up to 4000 A. The evaluation of GPC runs usually requires a separate calibration procedure. We attempted to determine the molecular weight of the eluate directly as it leaves the column. This is done by a special automatic viscometer that allows measurement of the viscosit…
Solution behavior of ethylcellulose in organic solvents
2007
Ethylcellulose has been investigated by osmotic pressure, sedimentation-diffusion, and light scattering measurements in dilute solutions of acetone, ethylacetate, 2-butanol, n-butylchloride, and benzene. Combining the results of different measuring techniques allowed the recognition and elimination of the influence of microgels present in the solution. The observed second virial coefficients are high as compared with those of the vinyl polymers and do not show a pronounced dependence on the type of solvent. On the other hand, the radius of gyration is nearly proportional to the root of the molecular weight. This behavior is discussed in connection with results on other cellulose ethers repo…
Macromolecules in ordered media: 5. Poly(4-vinyl pyridine)—liposome association induced by electrostatic interactions
1997
Abstract The association of water-soluble vinyl polymers to dimyristoyl phosphatidic acid unilamellar vesicles as a function of pH, temperature and salt content using steady-state fluorescence and viscometry has been investigated. Poly(4-vinyl pyridine) fluorescence data were converted to association isotherms and discussed in terms of binding and partition models. The results of this report support previous suggestions: (1) in the case of polyions the inclusion of the activity coefficient in both models is essential; (2) the parameters calculated using the two different theoretical approaches can be directly compared by the relating equation proposed for us. Finally, the excellent agreemen…
Prediction of maxima and minima in the curve of total sorption parameter in ternary polymer systems. Influence of ternary interaction parameter
1993
Flory-Huggins theory modified by Pouchly has been applied to predict maxima and minima in the curve of total sorption in ternary polymer systems formed by a polymer and two liquids. In this work, different diagrams based on experimental magnitudes easily obtained such as the difference in affinities of liquids, solvents and non solvents, and the solvent molar volume ratio. Total sorption parameter has been considered to be the decisive magnitude to define extrema conditions in both cosolvent and cononsolvent ternary polymer systems. The theoretical prediction is not altered by the inclusion of ternary interactions. Different examples of ternary systems dealing with vinyl polymers and polydi…
Synthesis of Heterotelechelic α,ω Dye-Functionalized Polymer by the RAFT Process and Energy Transfer between the End Groups
2009
The synthesis of a vinyl polymer with two different fluorescent dye end groups using reversible addition-fragmentation chain transfer (RAFT) polymerization is described. Use of a pentafluorophenyl (PFP) activated ester chain transfer agent (CTA) provided a polymer with an R end group that was reactive toward amines and a dithioester ω end group. The R PFP ester was amidated with Oregon Green Cadaverin. This did not harm the ω dithioester, which was subsequently aminolyzed with an excess of n-propylamine in the presence of Texas Red-2-sulfonamidoethyl methanethiosulfonate, resulting in a disulfide bond connecting the second dye to the polymer chain. Excess dyes and side products were removed…