The adsorption thermodynamics of copolymers, based on ethylene oxide (EO) and propylene oxide ( PO) units, at the laponite (RD) clay/liquid interface was determined at 298 K. The copolymer nature was tuned at molecular level by changing the hydrophilicity, the architecture and the molecular weight (Mw) keeping constant the EO/PO ratio. Polyethylene (PEGs) and polypropylene (PPGs) glycols with varying Mw and their mixture were also investigated to discriminate the role of the EO and the PO segments in the adsorption process. Enthalpies of transfer of RD, at fixed concentration, from water to the aqueous macromolecule solutions as functions of the macromolecule molality were determined. They were treated quantitatively by means of a model based on two equilibria: ( 1) one-to-one binding between the macromolecule and the site on the solid and ( 2) two-to-one binding following which one macromolecule interacts with another one adsorbed onto the solid. The good agreement between the equilibrium constants obtained from calorimetry and those determined from kinetic experiments conformed the reliability of the experimental and theoretical approaches. Almost all of the systems investigated are highlighted by the one-to-one binding; the L35 and 10R5 systems present both equilibria. The insights provided by the thermodynamics of adsorption of their homopolymers onto RD were fruitful in obtaining detailed information on the nature of the forces involved between RD and the copolymers. The data obtained in the present work clearly evidenced that for comparable polymer Mw, PPG is more suitable in building up a steric barrier around the RD particles and, indeed, exhibits several advantages and no drawbacks. Moreover, the parent copolymers may properly functionalize the RD surface by exploiting both their high affinity to the solid surface and the ability to self-assemble onto it as L35 and 10R5 clearly showed.

DE LISI, R., LAZZARA, G., LOMBARDO, R., MILIOTO, S., MURATORE, N., TURCO LIVERI, M.L. (2005). Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 7(23), 3994-4001 [10.1039/b510891h].

Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature

DE LISI, Rosario;LAZZARA, Giuseppe;LOMBARDO, Renato;MILIOTO, Stefana;MURATORE, Nicola;TURCO LIVERI, Maria Liria
2005-01-01

Abstract

The adsorption thermodynamics of copolymers, based on ethylene oxide (EO) and propylene oxide ( PO) units, at the laponite (RD) clay/liquid interface was determined at 298 K. The copolymer nature was tuned at molecular level by changing the hydrophilicity, the architecture and the molecular weight (Mw) keeping constant the EO/PO ratio. Polyethylene (PEGs) and polypropylene (PPGs) glycols with varying Mw and their mixture were also investigated to discriminate the role of the EO and the PO segments in the adsorption process. Enthalpies of transfer of RD, at fixed concentration, from water to the aqueous macromolecule solutions as functions of the macromolecule molality were determined. They were treated quantitatively by means of a model based on two equilibria: ( 1) one-to-one binding between the macromolecule and the site on the solid and ( 2) two-to-one binding following which one macromolecule interacts with another one adsorbed onto the solid. The good agreement between the equilibrium constants obtained from calorimetry and those determined from kinetic experiments conformed the reliability of the experimental and theoretical approaches. Almost all of the systems investigated are highlighted by the one-to-one binding; the L35 and 10R5 systems present both equilibria. The insights provided by the thermodynamics of adsorption of their homopolymers onto RD were fruitful in obtaining detailed information on the nature of the forces involved between RD and the copolymers. The data obtained in the present work clearly evidenced that for comparable polymer Mw, PPG is more suitable in building up a steric barrier around the RD particles and, indeed, exhibits several advantages and no drawbacks. Moreover, the parent copolymers may properly functionalize the RD surface by exploiting both their high affinity to the solid surface and the ability to self-assemble onto it as L35 and 10R5 clearly showed.
2005
DE LISI, R., LAZZARA, G., LOMBARDO, R., MILIOTO, S., MURATORE, N., TURCO LIVERI, M.L. (2005). Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 7(23), 3994-4001 [10.1039/b510891h].
File in questo prodotto:
File Dimensione Formato  
Adsorption_pluronic_laponite.pdf

Solo gestori archvio

Dimensione 603.44 kB
Formato Adobe PDF
603.44 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/33403
Citazioni
  • ???jsp.display-item.citation.pmc??? 2
  • Scopus 27
  • ???jsp.display-item.citation.isi??? 26
social impact