@article{woodhead_hall_2011, title={Encapsulation Efficiency and Micellar Structure of Solute-Carrying Block Copolymer Nanoparticles}, volume={44}, ISSN={["0024-9297"]}, DOI={10.1021/ma102938g}, abstractNote={We use discontinuous molecular dynamics (DMD) computer simulation to investigate the encapsulation efficiency and micellar structure of solute-carrying block copolymer nanoparticles as a function of packing fraction, polymer volume fraction, solute mole fraction, and the interaction parameters between the hydrophobic head blocks and between the head and the solute. The encapsulation efficiency increases with increasing polymer volume fraction and packing fraction but decreases with increasing head-head interaction strength. The latter is due to an increased tendency for the solute to remain on the micelle surface. We compared two different nanoparticle assembly methods, one in which the solute and copolymer co-associate and the other in which the copolymer micelle is formed before the introduction of solute. The assembly method does not affect the encapsulation efficiency but does affect the solute uptake kinetics. Both head-solute interaction strength and head-head interaction strength affect the density profile of the micelles; increases in the former cause the solute to distribute more evenly throughout the micelle, while increases in the latter cause the solute to concentrate further from the center of the micelle. We explain our results in the context of a model of drug insertion into micelles formulated by Kumar and Prud'homme; as conditions become more conducive to micelle formation, a stronger energy barrier to solute insertion forms which in turn decreases the encapsulation efficiency of the system.}, number={13}, journal={MACROMOLECULES}, author={Woodhead, Jeffrey L. and Hall, Carol K.}, year={2011}, month={Jul}, pages={5443–5451} }
 @article{woodhead_hall_2010, title={Simulation of Micelle Formation in the Presence of Solutes}, volume={26}, ISSN={["0743-7463"]}, DOI={10.1021/la1024444}, abstractNote={We investigate solute encapsulation by copolymer micelles by performing discontinuous molecular dynamics simulations on a model solute-copolymer-solvent system. In this paper, we detail the effect of system density, copolymer mole fraction, and hydrophobic interaction between copolymer head and solute on the encapsulation efficiency and phase behavior of the system. The relative hydrophobicity of solute and copolymer head units acts as a coupling parameter that determines whether the system encapsulates or the copolymer and solute aggregate separately. The presence of solute particles makes micelles form more easily than they would otherwise. Five different mesophases or morphologies are possible. The micelle-unimer transition that occurs in a solute-free copolymer-solvent system is, for moderately hydrophobic solute particles, replaced by a transition between a micelle phase and a morphology in which copolymers surround a large aggregate of solute particles. The best encapsulation occurs for highly hydrophobic solute particles where solutes are dispersed throughout the micelle's core. The manner in which our results might be used by experimentalists to improve the encapsulation behavior of drug-copolymer systems is discussed.}, number={19}, journal={LANGMUIR}, author={Woodhead, Jeffrey L. and Hall, Carol K.}, year={2010}, month={Oct}, pages={15135–15141} }