A. Temperature Chambers 1735 B. Pressure Cells 1735 C. Stretching Equipment 1736 D. Fiber Spinning Equipment 1737 E. Fiber Drawing Apparatus 1738 F. Shear Apparatus 1739 IV. Combined Techniques 1739 A. Simultaneous SAXS/WAXD 1739 B. Raman Spectroscopy 1740 C. Laser Light Scattering 1741 D. Fourier Transform IR Spectroscopy 1743 V. Applications 1743 A. Materials-Based Studies 1743 1. Block Copolymers 1743 2. Ionomers 1745 3. Liquid Crystalline Polymers 1745 4. Biopolymers 1746 B. Phenomenon-Based Studies 1747 1. Polymer Solutions and Gels 1747 2. Colloidal Suspensions, Micellar Solutions, and Microemulsions 1749

/pdf/small-angle-x-ray-scattering-of-polymers-1ui4u6nupr.pdf

Small-angle X-ray scattering of polymers.

A series of relatively monodisperse samples of poly(N-isopropylacrylamide) were synthesized by reversible addition−fragmentation chain transfer (RAFT) over the molecular weight range 2 × 103−3 × 105. For molecular weights below 4 × 104, conditions were found so that polydispersity remained below 1.4 up to high conversion (72%). Molecular weight distributions of polymer obtained using GPC in THF and MALDI were in accord for the low molecular weight range (typically 105). Particular care is required in GPC sample preparation:  it is necessary to ensure that trace amounts of water are initially present when drying a polymer sample prior to dissolution in THF, to avoid irreversible chain aggregation. The log/log plot of intrinsic viscosity against molecular weight for polyNIPAM was found to be linear for molecular weights <105, after which the hydrodynamic volume seems to be independent of molecular weight. The Mark−Houwink parameters obtained from the lower molecular weight data are K = 10-(4.24±0.42) dL g-1...

Molecular weight characterization of poly(N-isopropylacrylamide) prepared by living free-radical polymerization

Small-angle neutron scattering (SANS) and rheometry were used to investigate the supramolecular structure formed by a poly(oxyethylene−oxypropylene−oxyethylene) (PEO100PPO65PEO100, Pluronic F127) copolymer in aqueous solution over a temperature range of 10−75 °C and a concentration range of 10−20 wt %. At copolymer concentrations of less than 12.5% the solutions are Newtonian fluids. Gels with an ordered structure (cubic packing of spherical micelles) are observed over a well-defined temperature window when the copolymer concentrations are greater than 17 wt %. The SANS results show that the aggregation number of the micelles is independent of temperature and concentration. Low-yield stresses, very high zero shear viscosities (∼106 P), and shear thinning are the major rheological characteristics of the gels. Near, but outside, the gel phase boundary the solutions are non-Newtonian (shear thinning). However, SANS shows these solutions contain domains having the same structure as that in the gel phase. The ...

Structure and Rheology Studies of Poly(oxyethylene−oxypropylene−oxyethylene) Aqueous Solution

Inverse gas chromatography as a source of physiochemical data.

https://web.itu.edu.tr/okayo/pdf/03polymine.pdf

Effect of hydrolysis on spatial inhomogeneity in poly(acrylamide) gels of various crosslink densities

Laser light scattering has been used to study the solution behavior in aqueous NaCl of poly(acrylamide) (PAM), polymerized by using two different polymerization processes:  solution (S) and microemulsion (M). Results show that poly(acrylamide) samples polymerized from the microemulsion polymerization process behave as branched flexible chains, but poly(acrylamide) samples synthesized from solution polymerization exhibit a fairly expanded flexible coil−chain behavior. By combining the static light scattering results with the characteristic linewidth distribution, as determined by a Laplace inversion of the intensity−intensity time correlation function, the molecular weight distribution (MWD) and the radius of gyration distribution (RGD) could be estimated. The molecular weight dependence of the z-average diffusion coefficient (Dz) was determined during this conversion, with Dz0 = (3.05 × 10-4) Mw-0.585 cm2 s-1 and Dz0 = (1.52 × 10-4) Mw-0.518 cm2 s-1 for PAM(S) and PAM(M), respectively, with the weight ave...

Laser Light Scattering of Poly(acrylamide) in 1 M NaCl Aqueous Solution

Synchrotron small angle X-ray scattering (SAXS) was used to study the supramolecular structure formed by a block copolymer, Pluronic L64 (PEO[sub 13]PPO[sub 30]PEO[sub 13]), in xylene/water mixtures. Lamellar structure was observed at very high polymer concentrations (e.g., C[degree] > 0.53 g/ml). The lamellar spacing was determined by the amount of solubilized water and the copolymer concentration, with the amount of water playing a more important role on the lamellar spacing than the copolymer concentration. The lamellar spacing was almost independent of temperature. However the scattering peak became broader with increasing temperature, implying that the micellar size became smaller. Experimental data could be fitted by the Teubner-Strey model, and the resulting periodicity was in good agreement with the lamellar spacing derived by using the Bragg equation.

Lamellar structure of block copolymer poly(oxyethylene-oxypropylene-oxyethylene) in xylene/water mixtures

The concentration fluctuations in a poly(2-chlorostyrene)/polystyrene (P2ClS/PS) blend and their changes induced by temperature jumps were studied using time-resolved synchrotron small-angle X-ray scattering (SAXS). The virtual structure factor, which represents a formal extension of the one-phase equilibrium structure factor into the two-phase region, has been obtained from the mean-field static susceptibilities measured in the one-phase region. Three sets of measurements at different jump temperatures (from 140C to 156.87C, to 166.96C, and then to 179.91C) were performed. In the metastable region (142-167C) the experiments indicate that the initial kinetics can be described by the theory developed by Binder, with relaxation times of chain molecules being in a scale of minutes. The values are comparable with the results of the self-diffusion coefficient (on the order of [approximately]10[sup [minus]15] cm[sup 2]s[sup [minus]1]) of poly(bromostyrene)/polystyrene blends measured in the molten state. In the small scattering wave vector q range the initial relaxation rates of concentration fluctuations increased with increasing q in accordance with theoretical predictions. However, the relaxation process did not clearly follow a simple exponential law. The relaxation rate became slower with increasing time. In the case of a deeper jump (at 179.91C), the relaxation rate changed its sign from positive to negative,more » with the concentration fluctuations growing and eventually leading to phase separation.« less

Synchrotron SAXS study of phase-separation kinetics in a poly(2-chlorostyrene)/polystyrene blend

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Laser Light Scattering of Poly(acrylamide) in 1 M NaCl Aqueous Solution

Lamellar structure of block copolymer poly(oxyethylene-oxypropylene-oxyethylene) in xylene/water mixtures

Synchrotron SAXS study of phase-separation kinetics in a poly(2-chlorostyrene)/polystyrene blend