Interaction between pentaethylene glycol n-octyl ether and low-molecular-weight poly(acrylic acid).
The interaction between pentaethylene glycol n-octyl ether (C8E5) and low-molecular-weight poly(acrylic acid) (PAA, M(w)=2000) in aqueous solution has been investigated by various experimental techniques at constant polymer concentration (0.1% w/w) with varying surfactant molality. Spectrofluorimetry, using pyrene as molecular probe, shows (i) the formation of surfactant-polymer aggregates at a surfactant molality (T(1)) lower than the critical micelle concentration (cmc) of C8E5 in water and (ii) the formation of free micelles at a surfactant molality (T(2)) slightly higher than the cmc. Fluorescence quenching measurements indicate that the presence of PAA induces a lowering of the C8E5 aggregation number. Calorimetry confirms spectrofluorimetric evidence; in addition, it shows the presence of weak interactions below T(1) between monomeric surfactant molecules and the polymer chains. Tensiometry shows that, above T(1), only a low fraction of surfactant molecules interact with the polymer and that free micelle formation occurs before polymer saturation. The peculiarities of the interaction between surfactants and low-molecular-weight polymers have been discussed.
D'Errico
Gerardino
G
Chemistry Department of Naples University "Federico II," Via Cintia, Complesso di Montesantangelo, I-80126 Naples, Italy. derrico@chemistry.unina.it
Ciccarelli
Donato
D
Ortona
Ornella
O
Paduano
Luigi
L
Sartorio
Roberto
R
D000179:Acrylates / Q000737:chemistry; D000180:Acrylic Resins / Q000737:chemistry*; D002151:Calorimetry; D004987:Ethers / Q000737:chemistry*; D006018:Glycols / Q000737:chemistry; D008823:Micelles; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry; D013696:Temperature
D000179:Acrylates; D000180:Acrylic Resins; D004987:Ethers; D006018:Glycols; D008823:Micelles; D011108:Polymers; D013501:Surface-Active Agents; C489458:pentaethylene glycol n-octyl ether; D011092:Polyethylene Glycols; C006903:carbopol 940; C036658:acrylic acid