Micellization of Acrylate-Based Amphiphilic Block Copolymers as a Function of Hydrophobic Core Chain Length: An Investigation into the Effects of Chain Rigidity and Molecular Weight on Self- Assembly

摘要

Molecular transport devices are often employed when hydrophilic surroundings prevent the transport of hydrophobic molecules within the body. Amphiphilic diblock copolymers can be synthesized which form micelles that are structurally similar to physiologically occurring micelles such as viruses carrying DNA and lipoproteins containing water insoluble compounds. Homopolymer chains were formed by Reversible Addition Fragmentation chain Transfer (RAFT) employing a Chain Transfer Agent (CTA). Diblock copolymers were synthesized from homopolymer and a second monomer to yield structures such as poly(tert-butyl acrylate-b-methyl acrylate). Hydrolysis of the tert-butyl acrylate block afforded the amphiphilic poly(acrylic acid-b-methyl acrylate) copolymer. In order to form polymeric micelles in aqueous milieu, intermolecular forces such as dispersion, hydrogen bonding, and electrostatic interactions allow for the hydrophobic block to segregate from its surroundings. Intermolecular forces can affect aggregation represented by polymer glass transition temperatures (Tg), as well as the degree of polymerization (Dp) of each respective block type. In decreasing the chain rigidity with acrylate based blocks, while increasing the chain molecular weight, a correlation between chain stiffness and block weight is currently being investigated. Micellization behavior of acrylate based amphiphilic block copolymers is being determined by H-NMR relaxation experiments in solvents of varying polarity.