Molecular modeling of poly(2-ethyl-2-oxazoline)
Bernard, Ayanna Malene
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Poly(2-ethyl-2-oxazoline) (PEOX) is a nonionic, synthetic polymer which is soluble in both a variety organic solvents and water. The negative entropy of mixing of this polymer in aqueous solution suggested that it adopts a rigid conformation such as a helix in aqueous solution. Hydrogen bonding between PEOX and water molecules is thought to facilitate a special conformation that is specific to aqueous solution. The intent of this work is to investigate the conformation of PEOX in aqueous solution and consequently propose the mechanism by which it would adsorb onto cellulose and make it a valuable additive in paper processing. This work ultimately contributes to the greater matter of understanding the mechanisms by which water solvates nonionic polymers. Viscometry measurements of PEOX in water show that its shape scales similar to a random coil and that its molecules collapse in the presence of sodium chloride. Investigation into the molecular structure of PEOX through molecular scale simulations have revealed that although a rigid helical conformation does not exist, the potential exists for PEOX to have secondary helical structure in both water and other solvents. Without the rigid predicted structure, however, it is not surprising that PEOX does not adsorb well on cellulose. Comparing this folded helical conformation to a random coil conformation reveals that the random coil produces a lower energy system in water.