Self-assembled nanoparticles of functional copolymers for photonic applications

• Published in: Journal of colloid and interface science 2010-08, Vol.348 (2), p.424-430
• Main Authors: Venditti, Iole, Fratoddi, Ilaria, Palazzesi, Christian, Prosposito, Paolo, Casalboni, Mauro, Cametti, Cesare, Battocchio, Chiara, Polzonetti, Giovanni, Russo, Maria Vittoria
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Copolymers; Density; Exact sciences and technology; Functional copolymers; General and physical chemistry; Nanoparticles; Photonic crystals; Photonics; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Polydispersity; Polyphenylacetylene; Scanning electron microscopy; Spectroscopy; Surface charge; XPS; ζ-Potential
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2010.04.061

Emulsion copolymerization of phenylacetylene (PA) with acrylic acid (AA) or N,N-dimethylpropargylamine (DMPA) produces functionalized nanoparticles (diameters 80–500 nm) with superficial charge density and three-dimensional photonic crystals property. A modified emulsion copolymerization of phenylacetylene (PA) with hydrophilic monomers having different functions, i.e., acrylic acid (AA) and N,N-dimethylpropargylamine (DMPA) respectively, yields functionalized polymeric P(PA-co-AA) and P(PA-co-DMPA) nanoparticles. The systematic investigation on the experimental parameters affecting size, surface charge and polydispersity of the copolymers (initiator concentration, reaction time, cosolvent and PA/comonomer ratios) allows to modulate the nanoparticle physico-chemical properties. Spherical shaped particles with diameters in the range 80–500 nm, low polydispersity (PI values in the range 1.11–1.30) and different surface charge densities, between 0.44 and 2.87 μC/cm 2, have been consistently obtained and characterized by means of Dynamic Light Scattering (DLS), laser Doppler electrophoretic and Scanning Electron Microscopy (SEM) studies. XPS measurements have provided information on the nanoparticles chemical surface structure and suggest that AA and DMPA units are preferentially distributed on the surface of the spheres. The nanospheres self-assemble giving large domains (9.5 × 14.5 μm). Photonic analysis of the self-assembled copolymeric nanoparticles has been performed by means of Spectroscopic Ellipsometry (SE) and Bragg reflection spectroscopy, both of them demonstrating a three-dimensional photonic crystal property of these systems.