Theory and computation for self-assembly in soft matter

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George Schatz of Northwestern University is supported by the Chemical Theory, Models and Computational Method program in the Division of Chemistry to develop theory and computational methods for modeling the self-assembly of large assemblies of molecules into functional nanostructures. The proposed work builds on an active program that the PI maintains in this field concerning soft materials that are relevant to mechanical, electrical and optical devices, and for biomedical applications. The methods span the range from brute force molecular dynamics methods, to accelerated and coarse-grained methods, to simple statistical mechanical models, and to multiscale methods that couple molecular and continuum approaches. These are combined with methods for templating, seeding and mechanical control of assembly to develop approaches that are either significantly more efficient than can otherwise be obtained or which provide better insights into the features that drive assembly. Modeling of on-going experiments by collaborators will include (1) seeded methods to accelerate assembly of peptide amphiphiles into micelles and more complex structures that are of use in wound healing applications; (2) a multiscale method applied to a liposome (treated by continuum mechanics) coated with a cross-linked polymer (treated by molecular dynamics) to study coating formation and bursting in drug delivery applications; (3) templated approaches for investigating the mechanism for accelerated assembly in nanografting self-assembled monolayers on Au(111) surfaces as well as accelerated DNA hybridization on gold nanoparticles surfaces; and (4) mechanically guided self-assembly for DNA linking of nanoparticles or molecules into aggregated structures, investigating mechanistic information and enabling studies of the effects on the assembly process of salts, multiply charged cations, nonaqueous solvents, and possibly ?pioneer? molecules that facilitate hydrogen bond formation.This project is concerned with computational modeling of the organized assembly of thousands of molecules into larger structures (fibers, surface coatings, gel-like materials) that have useful biological and materials functions, including applications to wound healing, to drug delivery, to therapeutics and diagnostics. The work involves the development of new computational methods which can predict what structures will form, how these structures vary with variations in the preparation conditions, and the biological functions of these structures. The proposed research projects will be pursued by undergraduate, graduate and postdoctoral students, and they will receive training in the theory and methods being used, and in the fabrication and applications of the materials being developed. Outreach activities include: (1) Software dissemination, particularly using the www.nanohub.org site where access to functioning versions of the codes is available for free, and includes documentation and examples; (2) The development of teaching materials related to self-assembly that are used in General Chemistry courses, both lectures and laboratories; (3) Use of self-assembly research materials in outreach at predominantly minority local schools through a chemistry organization (Phi Lambda Upsilon); (4) Courses and outreach activities related to publication ethics; (5) Summer REU projects, including minority students, (6) Activities associated with the Journal of Physical Chemistry which relate to self-assembly research; (7) Presentations to audiences, including the general public, at major scientific meetings and in visits to universities and laboratories; (8) Advising and mentoring graduate students and postdocs, including minorities and females.