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ABSTRACT Poly(1-adamantyl acrylate) (PAdA) exhibits much higher glass transition and degradation temperatures than other polyacrylates. However, the quantitative evaluation of the stiffness of this polymer chain has not been reported previously. In this study, the dilute solution properties and conformational characteristics of PAdA were evaluated using viscometry and scattering techniques. The unperturbed dimensions of this polymer were evaluated using the Burchard-Stockmayer-Fixman extrapolation and the touched-bead wormlike chain model. The PAdA chain has a comparable persistence length, diameter per bead and characteristic ratio to poly(methyl methacrylate) and polystyrene. All these results indicate that PAdA is less flexible than common polyacrylates. In addition, the second virial coefficients ( A2) of PAdA in different solvents obtained by static light scattering were compared. Among the solvents investigated, tetrahydrofuran is a moderate solvent. Radius of gyration of a polymer sample in the various solvents ranged from 16.8 to 30.3 nm. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1526-1531 [ABSTRACT FROM AUTHOR]

Well-defined linear and branched polystyrenes with complex architectures (regular combs and centipedes) were characterized via on-line size exclusion chromatography (SEC), in the good solvent tetrahydrofuran and the theta solvent trans-decalin, in order to measure their radii of gyration ( R g ), hydrodynamic radii ( R H ), and intrinsic viscosities. Various measures of the sizes of these macromolecules were plotted as a function of the retention volume ( V R ) in order to examine the validity of different universal calibration strategies for SEC. Hydrodynamic-based calibration curves were found to be universal, whereas a plot of log R g versus V R did not yield universal curves in either solvent. These findings are consistent with previously published data for linear and branched polymers in thermodynamically good solvents. In addition, good solvent data were used to derive values of the epsilon parameter relating radius of gyration-based and intrinsic viscosity-based chain shrinkage factors. Values of about 0.9 were found for both regular combs and centipedes. [ABSTRACT FROM AUTHOR]

On-line two-angle (15° and 90°) light scattering measurements with a gel permeation chromatography for linear and branched polystyrene in tetrahydrofuran (a good solvent) and in trans-decalin (a theta solvent) were made and compared with data from a multi-angle light scattering detector and literature values. Theoretically, weight-average molecular weight and the radius of gyration Rg can be determined accurately in the range where Rg2k2 is less than 1.2 (rod)∼1.7 (random coil); here, k is the absolute value of the scattering vector for a right angle detector with the Berry square root method. Molecular weight dependence of the radius of gyration obtained from the two-angle light scattering detector for linear and branched polystyrenes under different thermodynamic conditions were measured and found to be almost the same as values measured with a multi-angle light scattering detector and literature values in the appropriate range of molecular weight. [Copyright &y& Elsevier]

Abstract: Temperature induced conformational changes of poly(p-oligo(ethylene glycol) styrene) (POEGS) in aqueous solutions were investigated by small angle neutron scattering (SANS), neutron transmission and dynamic light scattering (DLS). The molecular weight of the polymer studied was 9400g/mol with a polydispersity index of 1.18 and each repeat unit of the polymer had four ethylene glycol monomer segments. The polymer was water soluble due to the hydrophilicity of the OEG side chains and these solutions showed lower critical solution temperature (LCST) depending on the concentration of the polymer. Measurements of solution behavior were made as a function of temperature in the range of 25–55°C for three polymer concentrations (0.1wt%, 0.3wt%, and 1.8wt%). Neutron transmission measurements were used to monitor the amount of polymer which precipitated or remained in solution above the cloud point temperature (T CP). DLS revealed the presence of large clusters in all solutions both below and above T CP while SANS provided information on the structure and interactions between individual chains. It was found that in the homogeneous region below T CP the shape of individual polymers in solution was close to ellipsoidal with the dimensions R a =37Å and R b =14Å and was virtually independent of temperature. The SANS data taken for the most concentrated solution studied (1.8wt%) were fit to the ellipsoidal model with attractive interactions which were approximated by the Ornstein–Zernike function with a temperature-dependent correlation length in the range of 24–49Å. The collapse of individual polymers to spherical globules with the radius of 15Å above T CP was observed. [Copyright &y& Elsevier]

The poly(C60-co-styrene)s prepared by radical copolymerizations of C60 and styrene in bulk were characterized by multiple-detector size-exclusion chromatographs consisting of a refractometer, a differential viscometer, and/or a right-angle laser-light scattering photometer. The multidetector systems enabled the determinations of reliable, absolute molecular weights of the copolymers. The plots of intrinsic viscosity vs. molecular weight and radius of gyration vs. molecular weight offered valuable information about the molecular architectures of the copolymers. The slopes of the plots reveal that the structure of the copolymer changes with its C60 content: the copolymer with a low C60 content of 0.58 wt% possesses a linear structure, whereas its conger with a high C60 content of 1.14 wt% possesses a branched structure. [Copyright &y& Elsevier]