"Schizophrenic" Micellization Of Poly(Acrylic Acid)-b-poly(2-dimethylamino)Ethyl Methacrylate And Its Nanostructural Fixation

A typical "schizophrenic" block copolymer is a AB diblock copolymer synthesized by group transfer polymerization (GTP) or living radical polymerisation (ATRP or RAFT). The schizophrenic block copolymers can self-assembled into two distinct types of micelle structures (A-core/B-corona and B-core/A-corona structures) in aqueous solution in response to specific stimuli such as temperature, pH, ionic strength and light. The schizophrenic micellization of block copolymer has draw much attention due to the attractive protential applications.The well-defined double hydrophilic block copolymers (DHBC) block copolymer poly(acrylic acid)-b-poly(2-dimethylamino)ethyl methacrylate (PAA-b-PDMAEMA) was synthesized by sequential atom transfer radical polymerization (ATRP) using protected group chemisty. The block copolymers exhibit so-called "schizophrenic" micellization behavior at different pH values. The temperature responsive and aggregation behaviors of the "schizophrenic" micelles were studied in detail. The main results achieved are as follows:1. Sequential ATRP was utilized to synthesize the well-defined diblock copolymer poly(t-butyl acrylate)-b-poly(2-dimethylamino)ethyl methacrylate (PtBA-b-PDMAEMA), then the "schizophrenic" block copolymer poly (acrylic acid)-b-poly(2-dimethylamino)ethyl methacrylate (PAA-b-PDMAE MA) was obtained by hydrolysis in acidic conditions.2. The block copolymer exhibit schizophrenic micellization behavior at different pH values. The temperature responsive and aggregation behaviors of the "schizophrenic" micelles were studied in detail:PDMAEMA-core micelles and PAA-core-micelles were observed via dynamic light scattering (DLS) and UV-vis transmittance. Furthermore, the effect of electrolyte (NaCl) on aggregation behavior and morphology of PAA-b-PDMAEMA was investigated.3. The shell of the micelles was cross-linked by1,2-bis-(2-iodoethoxy) ethane (BIEE). The effect of the molar ratio between BIEE and PDMAEMA ([BIEE]/[PDMAEMA]) on the cross-linking was investigated in detail. It was found that the best shell-cross-linking is at the [BIEE]/[PDMAEMA] ratio of0.5, the pH and thermo responsive behaviors of shell-cross-linked micelle were studied. Futher more, we developed a novel way to prepare the zwitterionic SCL micelles with PAA inside.4. Poly(t-butyl acrylate)-b-poly(2-dimethylamino)ethyl methacrylate (PtBA-b-PDMAE MA) and poly(t-butyl acrylate)-b-poly(N-Isopropyl acrylamide)(PtBA-b-PNIPAM) synthesized by sequential ATRP. The micelles with complex-shell structure were formed in selective solvent. The controlled release for drug of complex-shell block copolymer micelles was characterized by ultraviolet spectrum (UV). The results indicate that channels on the complex-shell of micelles can control the release of drug.