0000000000019921
AUTHOR
Nannan Li
Rapid Production of Internally Structured Colloids by Flash Nanoprecipitation of Block Copolymer Blends.
Colloids with internally structured geometries have shown great promise in applications ranging from biosensors to optics to drug delivery, where the internal particle structure is paramount to performance. The growing demand for such nanomaterials necessitates the development of a scalable processing platform for their production. Flash nanoprecipitation (FNP), a rapid and inherently scalable colloid precipitation technology, is used to prepare internally structured colloids from blends of block copolymers and homopolymers. As revealed by a combination of experiments and simulations, colloids prepared from different molecular weight diblock copolymers adopt either an ordered lamellar morph…
Controlled production of patchy particles from the combined effects of nanoprecipitation and vitrification
Using molecular dynamics simulations, we study a simple and scalable method for fabricating patchy nanoparticles via the assembly of binary polymer blends under a rapid solvent exchange. Patchiness can be achieved by incorporating a glassy component, which kinetically traps the particle morphology along the path to the equilibrium configuration. Our simulations reveal that the number of surface patches increases for larger nanoparticles and for more asymmetric blend ratios, while the size distribution of the patches remains rather uniform. Other than multi-patch nanoparticles, Janus structures have been obtained for small nanoparticles. Further, ribbon structures with elongated surface doma…
Structured Nanoparticles from the Self-Assembly of Polymer Blends through Rapid Solvent Exchange
Molecular dynamics simulations were performed to study systematically the rapid mixing of a polymer blend in solution with a miscible nonsolvent. In agreement with experiments, we observe that polymers self-assemble into complex nanoparticles, such as Janus and core-shell particles, when the good solvent is displaced by the poor solvent. The emerging structures can be predicted on the basis of the surface tensions between the polymers as well as between the polymers and the surrounding liquid. Furthermore, the size of the nanoparticles can be independently tuned through the mixing rate and the polymer concentration in the feed stream; meanwhile, the composition of the nanoparticles can be c…
Multi-scale simulations of polymeric nanoparticle aggregation during rapid solvent exchange.
Using a multi-scale approach which combines both molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations, we study a simple and scalable method for fabricating charge-stabilized nanoparticles through a rapid solvent exchange, i.e., Flash NanoPrecipitation (FNP). This multi-scale approach is based on microscopic information from MD simulations and uses a KMC algorithm to access macroscopic length- and time scales, which allows direct comparison with experiments and quantitative predictions. We find good agreement of our simulation results with the experiments. In addition, the model allows us to understand the aggregation mechanism on both microscopic and macroscopic levels and det…
A Statistical Model of Spine Shape and Material for Population-Oriented Biomechanical Simulation
In population-oriented ergonomics product design and musculoskeletal kinetics analysis, digital spine models of different shape, pose and material property are in great demand. The purpose of this study was to construct a parameterized finite element spine model with adjustable spine shape and material property. We used statistical shape model approach to learn inter-subject shape variations from 65 CT images of training subjects. Second order polynomial regression was used to model the age-dependent changes in vertebral material property derived from spatially aligned CT images. Finally, a parametric spine generator was developed to create finite element instances of different shapes and m…
Self-Assembly of Polymer Blends and Nanoparticles through Rapid Solvent Exchange.
Molecular dynamics simulations were performed to study the fabrication of polymeric colloids containing inorganic nanoparticles (NPs) via the flash nanoprecipitation (FNP) technique. During this process, a binary polymer blend, initially in a good solvent for the polymers, is rapidly mixed with NPs and a poor solvent for the polymers that is miscible with the good solvent. The simulations reveal that the polymers formed Janus particles with NPs distributed either on the surface of the aggregates, throughout their interior, or aligned at the interface between the two polymer domains, depending on the NP-polymer and NP-solvent interactions. The loading and surface density of NPs can be contro…