Competitive adsorption of lysozyme and C12E5 at the air/liquid interface by Green, R, Su, T, Lu, JR, Webster, J, Penfold, J

“…The surface tension showed little variation with the addition of C12E5 over the low surfactant concentration region, but with the increase of C12E5 concentration, the surface tension gradually became identical to that corresponding to pure C12E5. …”

Apparent anomalies in surface excesses determined from neutron reflection and the Gibbs equation in anionic surfactants with particular reference to perfluorooctanoates at the air/... by An, S, Lu, JR, Thomas, R, Penfold, J

“…The surface tension and neutron reflectivity of several perfluorooctanoic acid salts with monovalent metal cations have been investigated over a wide range of surfactant, counterion, and co-ion concentrations. …”

Neutron reflection study of a double-Chained sugar surfactant by Cooke, D, Lu, JR, Lee, E, Thomas, R, Pitt, A, Simister, E, Penfold, J

“…Neutron reflection and surface tension have been used to investigate the structural features exhibited at the air-liquid interface by an adsorbed layer of the sugar-based nonionic surfactant 7,7-bis[(1,2,3,4,5-pentahydroxyhexanamido)methyl]-n-tridecane. …”

The influence of sorbitol on the adsorption of surfactants at the air-liquid interface by Staples, E, Thompson, L, Tucker, I, Penfold, J, Thomas, R, Lu, JR

“…Neutron reflection and surface tension have been used to study the adsorption of the nonionic surfactant monododecyl hexaethylene glycol (C12E6) and the mixed nonionic-anionic surfactants n-dodecyl triethylene glycol (C12E3) and Sodium dodecyl sulfate (SDS) at the air-liquid interface. …”

The determination of segment density profiles of polyethylene oxide layers adsorbed at the air-water interface by Lu, JR, Su, T, Thomas, R, Penfold, J, Richards, R

“…The adsorption of polyethylene oxide of molecular weight 17 800 and 87 000 at the air/water interface has been studied by neutron reflection and surface tension measurements. Over the concentration range 10-4-10-1 wt% of polymer the surface excesses determined by neutron reflection were consistent with the results derived from the surface tension using the Gibbs equation. …”

Neutron reflection study of butanol and hexanol adsorbed at the surface of their aqueous solutions by Li, Z, Lu, JR, Thomas, R, Rennie, A, Penfold, J

“…The surface excesses are in good agreement with previous surface tension measurements. The thicknesses of the alcohol layers have been determined as a function of concentration and the separation of their surface distributions from that of water has been determined. …”

Interaction between poly(ethylene oxide) and sodium dodecyl sulfate studied by neutron reflection by Cooke, D, Dong, C, Lu, JR, Thomas, R, Simister, E, Penfold, J

“…The adsorption of surfactant increases steadily with concentration and shows no sign of a discontinuity at the CAC (4.5 mM at 35°C), which is consistent with the break in the surface tension curve being caused only by the onset of surfactant/polymer aggregation in the bulk solution. …”

Limitations in the application of the Gibbs equation to anionic surfactants at the air/water surface: sodium dodecylsulfate and sodium dodecylmonooxyethylenesulfate above and below... by Xu, H, Li, P, Ma, K, Thomas, R, Penfold, J, Lu, JR

“…The NR results for SDS are compared to the definitive surface tension (ST) measurements of EM, and the surface excesses agree over the range where they can safely be compared, from 2 to 6 mM. …”

The direct measurement of the interfacial composition of surfactant/polymer mixed layers at the air-water interface using neutron reflection by Lu, JR, Blondel, J, Cooke, D, Thomas, R, Penfold, J

“…At a fixed PEO concentration of 0.1 wt%, the variation of surface tension with concentration of CsDS showed two discontinuities, the first (X1) corresponding to the onset of formation of surfactant/polymer aggregates and the second (x2) corresponding to the onset of formation of pure surfactant aggregates. …”

Adsorption of sodium dodecyl sulfate at the surface of aqueous solutions of poly(vinylpyrrolidone) studied by neutron reflection by Purcell, I, Lu, JR, Thomas, R, Howe, A, Penfold, J

“…Comparison of the effect of added PVP on the surface tension with the neutron reflection measurements indicates that, even below the CAC, the surfactant complexes to the polymer to some extent in the bulk solution. …”

The monolayer structure of the branched nonyl phenol oxyethylene glycols at the air-water interface by Green, SR, Su, T, Lu, JR, Penfold, J

“…The structure of the monolayers formed by a group of monodisperse nonyl phenol ethoxylates with para-substituted 1-butylpentyl chains (para-(C4H9)2CHC6H 4(OC2H4)nOH, abbreviated to BNPEn, n = 4, 8, and 12) at the air-water interface has been determined by surface tension measurements and neutron reflection. The critical micellar concentration (cmc) was found to be 1.1 ± 0.3 × 10-5 M for BNPE4, 4.0 ± 0.3 × 10-5 M for BNPE8 and 8.0 ± 0.3 × 10-5 M for BNPE12 and the limiting area per molecule (Acmc) at the cmc to be 46 ± 3, 61 ± 4, and 75 ± 5 Å2, respectively. …”

Application of the Gibbs equation to the adsorption of nonionic surfactants and polymers at the air-water interface: comparison with surface excesses determined directly using neut... by Li, P, Li, Z, Shen, H, Thomas, R, Penfold, J, Lu, JR

“…Four recent papers by Menger et al. have questioned methods of analysis of surface tension (ST) data that use the Gibbs equation to obtain the surface excess (Γ) of a surfactant at the air-water interface. …”

Adsorption of single chain zwitterionic phosphocholine surfactants: effects of length of alkyl chain and head group linker. by Yaseen, M, Lu, JR, Webster, JR, Penfold, J

“…The adsorption of a range of single chain zwitterionic phosphocholine surfactants (C(n)P(m)C) at the air/liquid interface has been studied by a combination of surface tension and neutron reflectivity. The critical micellar concentration (CMC) for C(n)PC (or C(n)P(2)C), where n varied from 12, 14 to 16, was found to be 0.91, 0.14, and 1.2 x 10(-2) mM respectively, and followed the same trend as observed for other zwitterionic and non-ionic surfactants. …”