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Fluorescence probe methods were applied to investigate micelle formation of poly(N-isopropylacrylamide) (PNIPA) with surfactant, sodium n-dodecyl sulfate (SDS) or n-dodecyltrimethylammonium chloride (DTAC), in aqueous solutions. Two PNIPA samples, one having a hydrophobic chain-end group (M sample) and the other having a negatively charged hydrophilic chain-end group (R sample), were used to investigate the effects of the chain-end group on the micelle formation. It is found that the microenvironmental polarity in the formed micelles depends on the kinds of chain-end group and surfactant.

We determined intrinsic viscosity for polystyrene (PS) samples with a wide range of molecular weight in d-limonene, which attracts interest as an environmentally friendly solvent for PS. By analyzing the experimental data obtained in d-limonene using the helical wormlike chain model with and without the excluded-volume effect, solvent quality of d-limonene for PS was quantitatively evaluated. Consequently, it was concluded that d-limonene belongs to the category of medium solvent, which is intermediate between good solvents like toluene and poor solvents like cyclohexane, for PS.

Static light scattering measurements are carried out for poly(ethylene glycol) and poly(ethylene oxide) (PEO) of the weight-average molecular weight M _w ranging from 3×10³ to 2×10⁴ in methanol and water at 25.0 °C. Some aggregates of large size are found to be formed only in the cases of PEO of M _w∼O(10³) in aqueous solutions, although for other cases polymer chains are isolated in solutions.

The cloud point was determined for aqueous solutions of two poly(N-isopropylacrylamide) samples, one having a hydrophobic nonionic chain-end group (M sample) and the other having a hydrophilic anionic chain-end group (R sample), with an addition of two kinds of surfactants, anionic sodium n-dodecyl sulfate (SDS) or cationic n-dodecyltrimethylammonium chloride (DTAC). It is found that behavior of the cloud point as a function of the concentration c_s of the surfactants largely depends on the kinds of chain-end group and surfactant.

The intermolecular interactions between polystyrene (PS) and d-limonene were comprehensively studied utilizing both light-scattering experiments and computational simulations. From analyses of the mean-square radius of gyration 〈S²〉 and second virial coefficient A₂ for PS in d-limonene determined by the light-scattering experiments, d-limonene was confirmed as a medium solvent with intermediate solvent quality between good solvents like toluene and poor solvents like cyclohexane for PS. The intermolecular interaction energy between repeat unit of PS and d-limonene, which was obtained from the computational simulations, supported the estimated solvent quality for PS.

The cloud points in aqueous solutions of poly(N-isopropylacrylamide) samples synthesized by aqueous redox polymerization (R) were found to be definitely higher than those of samples previously synthesized by radical polymerization using azobis(isobutyronitrile) as an initiator in tert-butanol (T) and benzene (B). Further, dependence of the cloud point on the weight-average molecular weight M_w for the R sample was found to be opposite to those for the T and B samples.

The cloud point was determined in aqueous poly(N,N-diethylacrylamide) (PDEA) solutions. It was found that the cloud-point curve of each PDEA sample has a critical point and each PDEA solution exhibits phase separation into two liquid phases when the temperature is increased above its cloud point, which has not been previously observed for aqueous poly(N-isopropylacrylamide) (PNIPA) solutions. Therefore, the aqueous PDEA solutions exhibit typical phase behavior of lower critical solution temperature type, which is substantially different from that observed for PNIPA.

The mean-square radius of gyration 〈S²〉 is determined for poly(di-tert-butyl fumarate) (PDtBF) for a range of weight-average number of repeat units n_w from 382 to 1520 in tetrahydrofuran at 30.0 °C. The data are analyzed on the basis of the Kratky–Porod (KP) wormlike chain with excluded volume (EV). It is shown that the average chain dimension of PDtBF is significantly larger than that of poly(diisopropyl fumarate) (PDiPF) because of a remarkable difference in chain stiffness between the two polymers.