0906898_Cheng

1. Self-Assembly of Giant Molecular Shape AmphiphilesStephen Z. D. Cheng, University of Akron, DMR 0906898 We have developed several unique synthetic approaches to prepare kinds of precisely-defined giant molecular shape amphiphiles for fabricating complex ordered supramolecular structures (JACS 2011, 133, 10712-10715; JACS 2012, 134, 7780-7787). Molecular nanoparticles, specifically C60 and POSS, were employed for the design of new amphiphiles with both building block shape and interaction anisotropy. Particularly, the self-assembly behaviors of POSS-based Janus particles (APOSS-BPOSS) and hydrophilic C60 based giant surfactants/lipids (AC60-PS/AC60-2PS) have been fully investigated. APOSS-BPOSS could self-organize into hierarchically ordered structures in the bulk. It was found to exhibit a bilayered lamellar morphology in the bulk with an orthorhombic unit cell. While the crystalline order can be lost upon heating, the bilayered structure persists throughout (Figure 1). Another study involving polymer-hydrophilic C60 conjugates with solution assemblies are also being conducted. AC60-PS44 and AC60-2PS23 are synthesized as a topological isomer pair of these shape amphiphiles. Interestingly, AC60-PS44 formed spherical micelles while AC60-2PS23 generated bilayer vesicles under identical conditions (Figure 2). Figure 1. (a) Chemical structure of APOSS-BPOSS; (b) TEM image of APOSS-BPOSS film; (c) Temperture-dependent SAXS patterns and (d) WAXD patterns of APOSS-BPOSS. Figure 2. General representation of the self-assembled morphologies of (a) monotethered AC60-PS44 and (b) ditethered AC60-2PS23 in solution under identical conditions.

2. Self-Assembly of Giant Molecular Shape AmphiphilesStephen Z. D. Cheng, University of Akron, DMR 0906898 EDUCATION: This grant has helped 2 students, Dr. Hao-Jan Sun and Dr. Xinfei Yu, earn their Ph.D. degrees at the University of Akron. It has also fully or partically supported 3 other students in their doctoral dissertation research. The unique combination of chemistry and physics needed for this work has helped these students obtain experience in both areas of polymer science. Some funding has also been used to help support the training and career development of 1 post-doctoral associate. OUTREACH: At the University of Akron (UA), there are various outreach programs for area students to experience the sciences. These programs include tours of the facilities, science days, and summer teaching programs. My group has often participated in the NSF-REU summer internship and BS/MS programs. In these programs, our group provides valuable graduate research experience to undergraduates in chemistry, physics or engineering disciplines. They are in our group working on the synthesis and self-assembly of POSS-based shape amphiphiles.