TY - JOUR
T1 - Synergy, competition, and the “hanging” polymer layer
T2 - Interactions between a neutral amphiphilic ‘tardigrade’ comb co-polymer with an anionic surfactant at the air-water interface
AU - Slastanova, Anna
AU - Campbell, Richard A.
AU - Snow, Tim
AU - Mould, Elizabeth
AU - Li, Peixun
AU - Welbourn, Rebecca J.L.
AU - Chen, Meng
AU - Robles, Eric
AU - Briscoe, Wuge H.
PY - 2020/3/1
Y1 - 2020/3/1
N2 - Understanding the structure of polymer/surfactant mixtures at the air-water interface is of fundamental importance and also of relevance to a variety of practical applications. Here, the complexation between a neutral ’tardigrade’ comb co-polymer (consisting of a hydrophilic polyethylene glycol backbone with hydrophobic polyvinyl acetate grafts, PEG-g-PVAc) with an anionic surfactant (sodium dodecyl sulfate, SDS) at the air-water interface has been studied. Contrast-matched neutron reflectivity (NR) complemented by surface tension measurements allowed elucidation of the interfacial composition and structure of these mixed systems, as well as providing physical insights into the polymer/surfactant interactions at the air-water interface. For both polymer concentrations studied, below and above its critical aggregation concentration, cac, (0.2 cac and 2 cac, corresponding to 0.0002 wt% or 0.013 mM and 0.002 wt% or 0.13 mM respectively), we observed a synergistic cooperative behaviour at low surfactant concentrations with a 1–2 nm mixed interfacial layer; a competitive adsorption behaviour at higher surfactant concentrations was observed where the polymer was depleted from the air-water interface, with an overall interfacial layer thickness ~1.6 nm independent of the polymer concentration. The weakly associated polymer layer “hanging” proximally to the interface, however, played a role in enhancing foam stability, thus was relevant to the detergency efficacy in such polymer/surfactant mixtures in industrial formulations.
AB - Understanding the structure of polymer/surfactant mixtures at the air-water interface is of fundamental importance and also of relevance to a variety of practical applications. Here, the complexation between a neutral ’tardigrade’ comb co-polymer (consisting of a hydrophilic polyethylene glycol backbone with hydrophobic polyvinyl acetate grafts, PEG-g-PVAc) with an anionic surfactant (sodium dodecyl sulfate, SDS) at the air-water interface has been studied. Contrast-matched neutron reflectivity (NR) complemented by surface tension measurements allowed elucidation of the interfacial composition and structure of these mixed systems, as well as providing physical insights into the polymer/surfactant interactions at the air-water interface. For both polymer concentrations studied, below and above its critical aggregation concentration, cac, (0.2 cac and 2 cac, corresponding to 0.0002 wt% or 0.013 mM and 0.002 wt% or 0.13 mM respectively), we observed a synergistic cooperative behaviour at low surfactant concentrations with a 1–2 nm mixed interfacial layer; a competitive adsorption behaviour at higher surfactant concentrations was observed where the polymer was depleted from the air-water interface, with an overall interfacial layer thickness ~1.6 nm independent of the polymer concentration. The weakly associated polymer layer “hanging” proximally to the interface, however, played a role in enhancing foam stability, thus was relevant to the detergency efficacy in such polymer/surfactant mixtures in industrial formulations.
KW - Air-water interface
KW - Comb co-polymer
KW - Competition
KW - Foaming
KW - Neutron reflectivity
KW - Polymer/surfactant interactions
KW - Synergy
UR - http://www.scopus.com/inward/record.url?scp=85075975694&partnerID=8YFLogxK
U2 - 10.1016/j.jcis.2019.11.017
DO - 10.1016/j.jcis.2019.11.017
M3 - Article (Academic Journal)
C2 - 31830734
AN - SCOPUS:85075975694
VL - 561
SP - 181
EP - 194
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
SN - 0021-9797
ER -