4(%3)3 - Ecole nationale supérieure de chimie de Montpellier

mg/ml),the micelles’ hydrodynamic diameter was found to be 35 nm at 25 o C (Figure – 4.13) asdetermined using Photon Cross Correlation Spectroscopy (PCCS).Differential Distribution1,210,80,60,40,200 20 40 60 80 100 120 140 160Diameter (nm)Figure – 4.13: Hydrodynamic diameter of PMMA-b-PODMA copolymer micelles as determined by PCCSFor the assembly of micelles, first a film of PMMA, made from uncontrolled free radicalpolymerization, was coated onto a thoroughly cleaned Silicon wafer using spin coating. The wafer wasthen partially dipped into the micellar solution of PMMA-b-PODMA for 1 hour, after which the coatedwafer was thoroughly rinsed with fresh cyclohexane to remove the physically adsorbed micelles. Oncedry, the wafer with two different surface characteristics was characterized by Atomic Force Microscopy(AFM) and contact angle measurement (CA).A compact assembly of micelles with an average micelle diameter of 15 nm was observed withno long-range ordering on the immersed part of the wafer (Figure – 4.14 a,c). When examining the Zheight at both extremity of the blue line drawn in the figure, a difference of about 13 nm was foundwhich is in agreement with a single micelle monolayer height (Figure – 4.14b). The peak observed at thetransition corresponds to a “pyramid” of 3 micelle layers. A possible reason for this can be attributed tothe slight evaporation of the solvent over the experiment time, creating a flux of micelles at the solventmeniscus thus increasing their local concentration.112