ИСТИНА

The present contribution is devoted to the study of impact of the volume of localization of polymer poly(4-vinylpyridine) (P4VP) on its conformation and flexibility by small-angle neutron scattering (SANS) and nuclear magnetic resonance (1H NMR). Two different states of polymer were investigated: polymer injected into the wormlike micelles of anionic surfactant potassium oleate and its diluted solution in dimethyl sulfoxide (DMSO), known to be good solvent for P4VP. To obtain SANS curves from P4VP injected into the wormlike micelles separately from molecules of potassium oleate mixture of water and deuterium oxide (D2O) was used to match the scattering from the surfactant. Deuterated dimethyl sulfoxide (dDMSO) was used instead of DMSO to increase the scattering intensity from P4VP in its diluted solution. For the polymer inside the micelles log-log scattering curves in the low-Q region demonstrate the slope close to -2, which is typical for macromolecules under θ-conditions suggesting that macromolecules of P4VP in this state have the conformation of a Gaussian coil. The same slope for the polymer solubilized in dDMSO was close to -1.6, that indicates the good solvent conditions for P4VP. Dependence log(IQ) on Q2 (Kratky plot) was used to obtain the values of persistent length of polymer in both cases. It was shown, that persistence length of polymer embedded into wormlike micelles at least 4 times larger than of polymer in dDMSO. To receive the information about the area of localization of P4VP inside the micelles was 1H NMR applied. From comparison of 1H NMR spectra of potassium oleate in the polymer-free and polymer-loaded micelles followed, that peaks most affected by addition of polymer belong to two methylene groups closest to the surfactant head (16th and 17th), indicating that the polymer is located inside the thin layer at the interface between the hydrophobic core and hydrophilic corona of the micelles. Thus, it was demonstrated that injection of P4VP into the reduced volume at the core-corona interface of wormlike micelles of the anionic surfactant potassium oleate leads to collapse of polymeric chain and loss of the flexibility.