1. Amphiphilic Polyethylenes Leading to Surfactant-Free Thermoresponsive Nanoparticles.
- Author
-
Kryuchkov, Vladimir A., Daigle, Jean-Christophe, Skupov, Kirill M., Claverie, Jérome P., and Winnik, Françoise M.
- Subjects
- *
POLYETHYLENE , *ACRYLIC acid , *COPOLYMERS , *HYDROLYSIS , *HYDROGEN bonding , *NANOPARTICLES , *INFRARED spectroscopy - Abstract
Linear copolymers of ethylene and acrylic acid (PEAA) were prepared by catalytic polymerization of ethylene and tert-butyl acrylate followed by hydrolysis of the ester groups. The copolymers contained COOH groups inserted into the crystalline unit cell with formation of intramolecular hydrogen-bonds, as established on the basis of differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) studies. A solvent-exchange protocol, with no added surfactant, converted a solution in tetrahydrofuran of a PEAA sample containing 12 mol % of acrylic acid (AA) into a colloidally stable aqueous suspension of nanoparticles. Transmission electron microscopy (TEM), dynamic light scattering (DLS), and high sensitivity differential scanning calorimetry (HS-DSC) were used to characterize the nanoparticles. They are single crystals of elongated shape with a polar radius of 49 nm (σ = 15 nm) and an equatorial radius of 9 nm (σ = 3 nm) stabilized in aqueous media via carboxylate groups located preferentially on the particle/water interface. The PEAA (AA: 12 mol %) nanoparticles dispersed in aqueous media exhibited a remarkable reversible thermoresponsive behavior upon heating/cooling from 25 to 80 °C. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF