title: Surfactant-activated microgels: a new pathway to rheology modification.
abstract: Alkali swellable microgels are widely used to control rheology of formulated products containing surfactants. However, formulations based on these pH-responsive polymers show undesirably large changes in yield stress in a range of pH close to the pKa of the acid group. Analysis of the behavior of a cross-linked copolymer of ethyl acrylate and methacrylic acid in the nonionized form (at pH below the pKa of methacrylic acid) in the presence of sodium dodecyl sulfate shows surfactant-mediated swelling (an increase in particle diameter by over 2.5×) and a peak in zero-shear viscosity versus surfactant concentration indicating surfactant-mediated interaction of the swollen microgels. On the basis of these results, we demonstrate a new class of nonionic microgels composed of hydrophobic alkyl acrylates and hydrophilic hydroxyalkyl esters that utilize the effects of surfactant-mediated swelling and interaction to provide pH-independent rheological properties.
authors.affiliation: Lubrizol Advanced Materials, Inc., 9911 Brecksville Road, Cleveland, Ohio 44141-3201, United States.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Chari
authors.forename: Raymond
authors.initials: R
authors.lastname: Hsu
authors.forename: Prachur
authors.initials: P
authors.lastname: Bhargava
authors.forename: Brian
authors.initials: B
authors.lastname: Figura
authors.forename: Wayne
authors.initials: W
authors.lastname: Yang
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Park
authors.forename: Ted
authors.initials: T
authors.lastname: Clifford
authors.forename: Murat
authors.initials: M
authors.lastname: Kadir
mesh_terms: D005782:Gels / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D012212:Rheology / Q000379:methods*; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity
chemical_list: D005782:Gels; D013501:Surface-Active Agents