Adsorption of Poly(ethylene oxide)-b-poly(ε-caprolactone) Copolymers at the Silica−Water Interface

• Published in: Langmuir 2005-03, Vol.21 (7), p.2930-2940
• Main Authors: Vangeyte, P, Leyh, B, Rojas, O. J, Claesson, P. M, Heinrich, M, Auvray, L, Willet, N, Jérôme, R
• Format: Article
• Language: English
• Subjects: Adsorption; aqueous-solution; block-copolymers; Chemistry; Chimie; Colloidal state and disperse state; competitive adsorption; diblock copolymers; Engineering, computing & technology; ethylene-oxide; Exact sciences and technology; General and physical chemistry; Hot Temperature; hydrophobic surfaces; Ingénierie, informatique & technologie; kinetics; Materials science & engineering; Micelles; Micelles. Thin films; nonionic surfactants; Physical, chemical, mathematical & earth Sciences; Physique, chimie, mathématiques & sciences de la terre; poly(caprolactone-b-ethylene oxide-b-caprolactone); Polyesters - chemistry; Polyethylene Glycols - chemistry; Science des matériaux & ingénierie; Silicon Dioxide - chemistry; Surface physical chemistry; triblock copolymers; Water - chemistry
• ISSN: 0743-7463; 1520-5827; 1520-5827
• DOI: 10.1021/la047425+

The adsorption of amphiphilic poly(ethylene oxide)-b-poly(ε-caprolactone) and poly(ethylene oxide)-b-poly(γ-methyl-ε-caprolactone) copolymers in aqueous solution on silica and glass surfaces has been investigated by flow microcalorimetry, small-angle neutron scattering (SANS), surface forces, and complementary techniques. The studied copolymers consist of a poly(ethylene oxide) (PEO) block of M n = 5000 and a hydrophobic polyester block of poly(ε-caprolactone) (PCL) or poly(γ-methyl-ε-caprolactone) (PMCL) of M n in the 950−2200 range. Compared to homoPEO, the adsorption of the copolymers is significantly increased by the connection of PEO to an aliphatic polyester block. According to calorimetric experiments, the copolymers interact with the surface mainly through the hydrophilic block. At low surface coverage, the PEO block interacts with the surface such that both PEO and PCL chains are exposed to the aqueous solution. At high surface coverage, a dense copolymer layer is observed with the PEO blocks oriented toward the solution. The structure of the copolymer layer has been analyzed by neutron scattering using the contrast matching technique and by tapping mode atomic force microscopy. The experimental observations agree with the coadsorption of micelles and free copolymer chains at the interface.