Properties of Linear-Dendritic Block Copolymers Studied Via Brownian Dynamics Simulation

Miguel A. Estremera, Chemical Engineer, University of Puerto Rico- MayagŁez, Calle Post, MayagŁez, PR 00681, Monica Lamm, Chemical and Biological Engineering, Iowa State University, Ames, IA 50014, and Nicholas W. Suek, Department of Chemical and Biological Engineering, Iowa State University, 2114 Sweeney Hall, Ames, IA 50011.

Block copolymers are composed of long sequences of the same monomer type, covalently bound to sequences of unlike type. The blocks can be connected in a variety of ways such as AB diblock and ABA triblock structures. In this research we consider a triblock ABA where A is the dendritic part and B represent the linear part. The A part is hydrophilic and the B is hydrophobic. This copolymer forms micelles in solution that can be a reservoir for genes, enzymes and drugs. Using Brownian dynamics computer simulation we have found the critical micelle concentration of a copolymer that consists of a dendron-coil-dendron topology for example PAMAM-PPG-PAMAM. The critical micelle concentration (cmc) is the maximum of the free chains concentration verses the total concentration; at the cmc the micelles are smaller and numerous. For concentrations above the cmc, we have determined properties such as, micelle size distribution, shape, and structure. The results are compared with those of a linear triblock structure to see the effect of architecture. The findings from this research are part of larger study aimed at understanding the properties of dendron copolymers used for drug delivery.