title: The design by molecular dynamics modeling and simulations of porous polymer adsorbent media immobilized on the throughpore surfaces of polymeric monoliths.
abstract: Ion-exchange porous adsorbent media having intermediate and low surface densities of dextran polymer grafted on the surface of the throughpores of polymeric monoliths are constructed and characterized by a molecular dynamics modeling and simulation approach that has also been shown to be effective in the construction and characterization of porous ion-exchange adsorbent media whose number of immobilized dextran polymer chains per unit surface area is high. The activation step that prepares the surface of the pores of the dextran polymer layer for the immobilization of the charged ligands insignificantly affected the pore structure of the dextran polymer layer, while this was found to not be the case for previously studied systems that involved high dextran polymer surface densities. Compared to the high dextran polymer density system studied previously, the intermediate dextran polymer density system can generate significantly larger pores but still possesses relatively high interconnection and mutual steric support between dextran chains to exhibit similar structural characteristics and responses to charged ligand immobilization, including dextran layer thickness, stability, monomer distribution, ligand-induced compact chain structures, dextran layer shrinkage, distributions of ligands and counterions, and local nonelectroneutrality. The low dextran polymer density system having relatively isolated dextran chains and insufficient mutual steric support can result in even larger pores than those obtained in the intermediate dextran polymer density system, but a significantly thinner porous dextran polymer layer and different dextran monomer distributions are obtained in the low dextran polymer density system. More importantly, the gradient of the local nonelectroneutrality after the immobilization of the charged ligands is significantly smaller in magnitude in the low dextran polymer density system than that obtained in the system having intermediate dextran polymer density, and, despite a lack of porous layer depth to accommodate adsorbate biomolecules in large amounts, it could still be useful for the effective transport and adsorption of very large biomolecules. Compared with the polymeric monoliths without a porous dextran polymer layer grafted on the surface of their throughpores, the intermediate and low dextran polymer density systems explored and studied in this work provide pore structures with desirable characteristics for the effective transport of adsorbate biomolecules and substantially larger effective surface areas and throughput capacities for the adsorption of the adsorbate biomolecules.
authors: Department of Chemical and Biological Engineering, Missouri University of Science and Technology, Rolla, Missouri 65409, USA.
authors: E
authors: E
authors: Riccardi
authors: J-C
authors: JC
authors: Wang
authors: A I
authors: AI
authors: Liapis