caa a22 4500 475764145 CHVBK 20180406123600.0 cr unu---uuuuu 170329e20000301xx s 000 0 eng 10.1007/s003960050042 doi (NATIONALLICENCE)springer-10.1007/s003960050042 Nuclear magnetic resonance relaxation studies of polyacrylamide solution [Elektronische Daten] [S.-Z. Mao, X.-D. Zhang, J.-M. Dereppe, Y.-R. Du]  The cohesive interaction among polymer chains in a polyacrylamide (PAAm)-D2O solution has been studied by NMR relaxation. The NMR relaxation times of PAAm in the good solvent D2O were measured at different temperatures. The results show that the solution system has a high local viscosity and that its relaxation characteristic is soft-solid-like. The temperature dependence of the relaxation behavior of the solution is obviously different from that of ordinary polymer solutions. The difference lies in the relaxation behavior of the methylene protons in the main chain of PAAm, as shown by analyzing the relaxation process with single exponential and biexponential decays. As the temperature increases, the solvation is weakened, leading polymer chains to form curling coils, thus hindering the movement of the methylene protons among the main chains. It can be expected from the existence of 80% fast-relaxing protons that there are a zhigh number of entanglements among the polymer chains in PAAm solution. The information about entanglements among the polymer chains can be deduced from the biexponential dependence of the spin-spin relaxation on the concentration of the polymer solutions. Springer-Verlag Berlin Heidelberg, 2000 Key words Polyacrylamide nationallicence Nuclear magnetic resonance nationallicence Relaxation nationallicence Cohesional entanglement nationallicence Mao S.-Z Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences P.O. Box 71010, Wuhan 430071, China e-mail: maosz@nmr.whcnc.ac.cn Fax: +86-27-87885291, CN aut Zhang X.-D Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences P.O. Box 71010, Wuhan 430071, China e-mail: maosz@nmr.whcnc.ac.cn Fax: +86-27-87885291, CN aut Dereppe J.-M Unite CPMC Universite de Louvain, Belgium, BE aut Du Y.-R Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences P.O. Box 71010, Wuhan 430071, China e-mail: maosz@nmr.whcnc.ac.cn Fax: +86-27-87885291, CN aut https://doi.org/10.1007/s003960050042 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s003960050042 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mao S.-Z Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences P.O. Box 71010, Wuhan 430071, China e-mail: maosz@nmr.whcnc.ac.cn Fax: +86-27-87885291, CN aut NATIONALLICENCE 700 1- Zhang X.-D Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences P.O. Box 71010, Wuhan 430071, China e-mail: maosz@nmr.whcnc.ac.cn Fax: +86-27-87885291, CN aut NATIONALLICENCE 700 1- Dereppe J.-M Unite CPMC Universite de Louvain, Belgium, BE aut NATIONALLICENCE 700 1- Du Y.-R Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences P.O. Box 71010, Wuhan 430071, China e-mail: maosz@nmr.whcnc.ac.cn Fax: +86-27-87885291, CN aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer