In this section
@article{Gonzalez:2018:10.1021/acs.macromol.8b00178,
author = {Gonzalez, Lopez C and Colby, R and Cabral, JP},
doi = {10.1021/acs.macromol.8b00178},
journal = {Macromolecules},
pages = {3165--3175},
title = {Electrostatic and hydrophobic interactions in NaCMC aqueous solutions: effect of degree of substitution},
url = {http://dx.doi.org/10.1021/acs.macromol.8b00178},
volume = {51},
year = {2018}
}
TY - JOUR
AB - The rheology of water soluble polyelectrolytesat intermediate and high concentrations is controlled byentanglements, hydrophobic and electrostatic interac-tions, whose influence is difficult to isolate. We investi-gate the rheology of semidilute solutions of sodium car-boxymethyl cellulose (NaCMC) with molecular weightMw'2.5×105g/mol and varying degree of substi-tution (D.S.) as a function of polymer concentration invarious solvent media: salt-free water (long ranged elec-trostatic interactions), 0.5M aqueous NaCl (screenedelectrostatics) and 0.5M aqueous NaOH (screened elec-trostatics, diminished hydrophobic interactions) in or-der to selectively probe the different interactions. De-creasing D.S. is found to decrease solubility and inducepartial aggregation and eventual gelation. In salt-freeand 0.5M NaCl solution, NaCMC with D.S.'1.2 ex-hibits hydrophilic polyelectrolyte and neutral polymerin good solvent behaviour respectively. Decreasing D.S.to'0.7-0.8 leads to hydrophobic behaviour in bothsolvents, becoming weak gels at high concentrations. In0.5M NaOH (pH = 13.5) the viscosities of samples withdifferent D.S. become identical when plotted againstthe overlap parameter, which we interpret as result-ing from the solubilisation of unsubstituted celluloseblocks. Small angle neutron scattering (SANS) data in-dicate that the polymer conformation is not stronglyaffected by hydrophobic interactions. By varying D.S.,ionic strength and pH, we demonstrate the tuning ofNaCMC-solvent interactions, controlling separately the electrostatic and hydrophobic effects on the solutionrheology.
AU - Gonzalez,Lopez C
AU - Colby,R
AU - Cabral,JP
DO - 10.1021/acs.macromol.8b00178
EP - 3175
PY - 2018///
SN - 0024-9297
SP - 3165
TI - Electrostatic and hydrophobic interactions in NaCMC aqueous solutions: effect of degree of substitution
T2 - Macromolecules
UR - http://dx.doi.org/10.1021/acs.macromol.8b00178
UR - http://hdl.handle.net/10044/1/58673
VL - 51
ER -