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

Figure – 4.12: 1 HNMR of Poly(methyl methacrylate)-b-Poly(octadecyl methacrylate)4.2 MICELLES PREPARATION AND THEIR SELF-ASSEMBLYThe classification of block copolymer micelles can be done on the basis of the type ofintermolecular forces segregating the core segment from the aqueous milieu. The first category isrepresented by amphiphilic micelles (hydrophobic interactions), second by polyion complex micelles(electrostatic interactions) and third represented by micelles emanating from metal complexation 30 .Generally, when the hydrophilic segment exceeds the core block in length, resulting micelle is sphericalin shape. By increasing the length of the core segment beyond that of the corona-forming chains, onemay generate various non-spherical structures including rods and lamellae 31 . In the present case, thecopolymer contains 65 % PODMA which is much more hydrophobic than 35 % PMMA block. To obtainspherical micelles from the copolymer, it was first dissolved in THF followed by slow addition ofcyclohexane which is a good solvent for PODMA but a poor one for PMMA. As the concentration ofcyclohexane increases more and more, the PMMA part is forced into forming the core while PODMAblock forms the corona. For a mixture of cyclohexane and THF (9/1; vol%) and concentration of (3.5111