Particles with surface heterogeneity or surface 'patchiness' are of general interest as building-blocks for the construction of hierarchical nanosystems. Of these, polymer-based nanoparticles are particularly attractive for their softer, more dynamic character, facilitating the construction process. Surface pattering of polymer particles at the nanometer scale, while challenging, can be accomplished through the use of assembling subunits with a molecular architecture that will lead to a 'clustering' effect. This award allows the exploration of the use of polymers with a bottle-brush architecture as subunits for the formation of 'patchy' nanoparticles. Unlike the more traditional linear polymers, considerably less is known about the assembly behavior of polymers with a complex architecture, opening new routes for the formation of polymer-based nanomaterials with unique functions. The research will examine solution self- and co-assembly of these polymers and establish relationships between polymer architecture, processing routes and aggregate morphology. Outreach efforts supported under this award will involve participation of undergraduate students in research, and community involvement through an education-based Latino outreach program targeting K-12 students.
The overarching goal of this award is to explore the molecular and processing determinants of assemblies from highly grafted polymers, with particular emphasis on the construction of nanoparticles exhibiting surface and core heterogeneity. Advances in controlled polymerization methods have enabled the synthesis of macromolecules with increasing functional and architectural complexity such as macromolecular brushes or bottle-brushes. In contrast to linear diblock copolymers, little is known about the factors that influence solution assembly of macromolecules. Furthermore, it has been previously shown that kinetic pathways of polymer assembly are determining factors of assembly morphologies from linear block copolymers, whereas the non-equilibrium behavior of macromolecules with more complex architectures remains unexplored. This award addresses two related objectives. First objective is to study nanoparticle formation from amphiphilic macromolecular brush copolymers by a rapid assembly process. This will allow to both elucidate the mechanism of brush copolymer assembly into multi-molecular nanoparticles, and determine absolute timescales of assembly. Second objective is to study the formation of complex heterogeneous nanosystems from amphiphilic macromolecular brush building-blocks. This involves co-assembly of families of macromolecular brushes with varying degrees of chemical dissimilarity through kinetic trapping. While there are many reported methods for fabricating composite nanoparticles exhibiting surface and/or core heterogeneity, clustering of relatively soft and adaptive building-blocks could provide the means for further intra-particle modifications.
