POLYMER DIMENSIONS IN GOOD SOLVENTS: CROSSOVER FROM SEMIDILUTE TO CONCENTRATED SOLUTIONS

Journal Article · Thu Jan 01 00:00:00 EST 2009 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.102.157801· OSTI ID:979156

Cheng, Gang ^[1]; Melnichenko, Yuri B ^[1]; Graessley, William ^[1]

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1. ORNL

Using small-angle neutron scattering, we studied the variation of the polymer radius of gyration (R{sub g}) as a function of polymer concentration ({phi}) for solutions of a flexible-chain poly(methyl methacrylate) in chloroform. We observed for the first time a distinct crossover between swollen coils in the semidilute regime, where R{sub g}{sup 2{infinity}}{phi}{sup -0.26{+-}0.03}, and unperturbed coils in the concentrated regime, where R{sub g} is independent on concentration. The crossover occurs at {phi}{double_dagger} {approx} 0.15, a value that agrees reasonably well with {phi}{double_dagger} {approx} 0.21 {+-} 0.035, estimated with a scaling relationship between {phi}{double_dagger} and the coil overlap concentration {phi}*.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 979156
• Journal Information: Physical Review Letters, Vol. 102, Issue 15; ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CHLOROFORM
DIMENSIONS
NEUTRONS
POLYMERS
SCATTERING
SOLVENTS