Characterisation of PAPEO-b-PAEMA based micelles using small angle neutron scattering

Due to the controlled micellisation and their role as both templating and functionalising agent, PolyIon Complex (PIC) micelles are a valuable asset for the synthesis of functionalised ordered mesoporous materials. They are assembled through the electrostatic complexation between a charged double hydrophilic block copolymer (DHBC) with an oppositely charged polyelectrolyte. Physico-chemical parameters, such as pH variation, can control their micellisation properties, which is of prime importance in devising of porous materials. Primarily, during the porous material synthesis, the silica precursor is allowed to condense over the PIC micelles acting as the template and once the condensation is completed the micelles are disassembled via pH change, revealing the porosity. We developed a new DHBC (RAFT polymerisation), P(APEO)m-b-P(AEMA)n, made of a poly(ethyleneoxidepolyacrylate) (PAPEO) neutral block and a positively charged aminoethyl methacrylate block (PAEMA). The electrostatic complexation of PAPEO-b-PAEMA, with negatively-charged poly-acrylic acid (PAA) can lead to micelle formation.
Each DHBC/counter-ion couple needs a specific charge ratio (CR) between negative and positive charges to obtain well-defined micelles. CR will depend on the DP of the PAEMA block and the molecular weight of PAA, which may also influence the size and shape of the micelles. Knowing the characteristics of these novel micelles is mandatory before using them for porous material synthesis.