TY - JOUR
T1 - Interaction between surfactants and colloidal latexes in nonpolar solvents studied using contrast-variation small-Angle neutron scattering
AU - Smith, Gregory
AU - Alexander, Shirin
AU - Brown, Paul
AU - Gillespie, David A J
AU - Grillo, Isabelle
AU - Heenan, Richard K.
AU - James, Craig
AU - Kemp, Roger D
AU - Rogers, Sarah E
AU - Eastoe, Julian
PY - 2014/4/1
Y1 - 2014/4/1
N2 - The interaction between deuterium-labeled Aerosol OT surfactant (AOT-d 34) and sterically stabilized poly(methyl methacrylate) (PMMA) latex particles dispersed in nonpolar solvents has been studied using contrast-variation small-Angle neutron scattering (CV-SANS). The electrophoretic mobilities (μ) of the latexes have been measured by phase-Analysis light scattering, indicating that μ is negative. Two analogues of the stabilizers for the particles have been studied as free polymers in the absence of PMMA latexes: poly(12-hydroxystearic acid) (PHSA) polyester and poly(methyl methacrylate)-graft-poly(12-hydroxystearic acid) (PMMA-graft-PHSA) stabilizer copolymer. The scattering from both PHSA in dodecane and PMMA-graft-PHSA in toluene is consistent with extended polymer chains in good solvents. In dodecane, PMMA-graft-PHSA forms polymer micelles, and SANS is consistent with ellipsoidal aggregates formed of around 50 polymer chains. CV-SANS measurements were performed by measuring SANS from systems of PHSA, PMMA-graft-PHSA, and PMMA latexes with 10 and 100 mM surfactant solutions of AOT-d34 in both polymer/particle and AOT contrast-matched solvent. No excess scattering above the polymer or surfactant was found for PHSA in dodecane or PMMA-graft-PHSA in dodecane and toluene. This indicates that AOT does not significantly interact with the free polymers. Excess scattering was observed for systems with AOT-d34 and PMMA latexes dispersed in particle contrast-matched dodecane, consistent with the penetration of AOT into the PMMA latexes. This indicates that AOT does not interact preferentially with the stabilizing layers but, rather, is present throughout the colloids. Previous research (Langmuir 2010, 26, 6967-6976) suggests that AOT surfactant is located in the latex PHSA-stabilizer layer, but all the results in this study are consistent with AOT poorly interacting with alkyl-stabilizer polymers.
AB - The interaction between deuterium-labeled Aerosol OT surfactant (AOT-d 34) and sterically stabilized poly(methyl methacrylate) (PMMA) latex particles dispersed in nonpolar solvents has been studied using contrast-variation small-Angle neutron scattering (CV-SANS). The electrophoretic mobilities (μ) of the latexes have been measured by phase-Analysis light scattering, indicating that μ is negative. Two analogues of the stabilizers for the particles have been studied as free polymers in the absence of PMMA latexes: poly(12-hydroxystearic acid) (PHSA) polyester and poly(methyl methacrylate)-graft-poly(12-hydroxystearic acid) (PMMA-graft-PHSA) stabilizer copolymer. The scattering from both PHSA in dodecane and PMMA-graft-PHSA in toluene is consistent with extended polymer chains in good solvents. In dodecane, PMMA-graft-PHSA forms polymer micelles, and SANS is consistent with ellipsoidal aggregates formed of around 50 polymer chains. CV-SANS measurements were performed by measuring SANS from systems of PHSA, PMMA-graft-PHSA, and PMMA latexes with 10 and 100 mM surfactant solutions of AOT-d34 in both polymer/particle and AOT contrast-matched solvent. No excess scattering above the polymer or surfactant was found for PHSA in dodecane or PMMA-graft-PHSA in dodecane and toluene. This indicates that AOT does not significantly interact with the free polymers. Excess scattering was observed for systems with AOT-d34 and PMMA latexes dispersed in particle contrast-matched dodecane, consistent with the penetration of AOT into the PMMA latexes. This indicates that AOT does not interact preferentially with the stabilizing layers but, rather, is present throughout the colloids. Previous research (Langmuir 2010, 26, 6967-6976) suggests that AOT surfactant is located in the latex PHSA-stabilizer layer, but all the results in this study are consistent with AOT poorly interacting with alkyl-stabilizer polymers.
UR - http://www.scopus.com/inward/record.url?scp=84897551427&partnerID=8YFLogxK
U2 - 10.1021/la500331u
DO - 10.1021/la500331u
M3 - Article (Academic Journal)
C2 - 24593803
AN - SCOPUS:84897551427
SN - 0743-7463
VL - 30
SP - 3422
EP - 3431
JO - Langmuir
JF - Langmuir
IS - 12
ER -