TY - JOUR
T1 - Charging Poly(methyl Methacrylate) Latexes in Nonpolar Solvents
T2 - Effect of Particle Concentration
AU - Smith, Gregory N.
AU - Ahualli, Silvia
AU - Delgado, Ángel V.
AU - Gillespie, David A.J.
AU - Kemp, Roger
AU - Peach, Jocelyn
AU - Pegg, Jonathan C.
AU - Rogers, Sarah E.
AU - Shebanova, Olga
AU - Smith, Nathan
AU - Eastoe, Julian
PY - 2017/11/28
Y1 - 2017/11/28
N2 - The electrophoresis of a well-established model system of charged colloids in nonpolar solvents has been studied as a function of particle volume fraction at constant surfactant concentration. Dispersions of poly(12-hydroxystearic acid)-stabilized poly(methyl methacrylate) (PMMA) latexes in dodecane were prepared with added Aerosol OT surfactant as the charging agent. The electrophoretic mobility (μ) of the PMMA latexes is found to decrease with particle concentration. The particles are charged by a small molecule charging agent (AOT) at finite concentration, and this makes the origin of this decrease in μ unclear. There are two suggested explanations. The decrease could either be due to the reservoir of available surfactant being exhausted at high particle concentrations or the interactions between the charged particles at high particle number concentrations. Contrast-variation small-angle neutron scattering measurements of PMMA latexes and deuterated AOT-d34 surfactant in latex core contrast-matched solvent were used to study the former, and electrokinetic modeling was used to study the latter. As the same amount of AOT-d34 is found to be incorporated with the latexes at all volume fractions, the solvodynamic and electrical interactions between particles are determined to be the explanation for the decrease in mobility. These measurements show that, for small latexes, there are interactions between the charged particles at all accessible particle volume fractions and that it is necessary to account for this to accurately determine the electrokinetic ζ potential.
AB - The electrophoresis of a well-established model system of charged colloids in nonpolar solvents has been studied as a function of particle volume fraction at constant surfactant concentration. Dispersions of poly(12-hydroxystearic acid)-stabilized poly(methyl methacrylate) (PMMA) latexes in dodecane were prepared with added Aerosol OT surfactant as the charging agent. The electrophoretic mobility (μ) of the PMMA latexes is found to decrease with particle concentration. The particles are charged by a small molecule charging agent (AOT) at finite concentration, and this makes the origin of this decrease in μ unclear. There are two suggested explanations. The decrease could either be due to the reservoir of available surfactant being exhausted at high particle concentrations or the interactions between the charged particles at high particle number concentrations. Contrast-variation small-angle neutron scattering measurements of PMMA latexes and deuterated AOT-d34 surfactant in latex core contrast-matched solvent were used to study the former, and electrokinetic modeling was used to study the latter. As the same amount of AOT-d34 is found to be incorporated with the latexes at all volume fractions, the solvodynamic and electrical interactions between particles are determined to be the explanation for the decrease in mobility. These measurements show that, for small latexes, there are interactions between the charged particles at all accessible particle volume fractions and that it is necessary to account for this to accurately determine the electrokinetic ζ potential.
UR - http://www.scopus.com/inward/record.url?scp=85035346557&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.7b02257
DO - 10.1021/acs.langmuir.7b02257
M3 - Article (Academic Journal)
C2 - 29064706
AN - SCOPUS:85035346557
SN - 0743-7463
VL - 33
SP - 13543
EP - 13553
JO - Langmuir
JF - Langmuir
IS - 47
ER -