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TEM images of PS 202 - b -PTBOS 35 , PS 567 - b -PTBOS 24 and PS 160 - b -PTBOS 126 .

Complex hierarchical self-assembly templated by block copolymers Christopher Li, Drexel University, DMR 0239415.

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TEM images of PS 202 - b -PTBOS 35 , PS 567 - b -PTBOS 24 and PS 160 - b -PTBOS 126 .

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  1. Complex hierarchical self-assembly templated by block copolymersChristopher Li, Drexel University, DMR 0239415 In rod-coil block copolymer (RCBCP) systems, there exists competition between the liquid crystallinity of the rods and block copolymer (BCP) phase separation. Most of the reported work showed that liquid crystallinity dominated the phase behavior and the sphere or gyroid phase was often degenerated into structures with planar inter-material dividing surface (IMDS). We recently found that, by decreasing the LC interactions, BCP separation could be the dominant factor in RCBCP phase structure formation. A core shell RCBCP was designed as the model system (poly[styrene-block-{3,5-bis[(4'-((4''-tetradecanoylbenzoyl)oxy)benzoyl)oxy]styrene}] (PS-b-PTBOS)), in which, the LC ordering of the rods was decreased by incorporating a soft shell around the rigid rod core. A novel H-in-L structure was observed in the symmetric BCP. The H symmetry was broken in the asymmetric BCPs, due to the lateral chain repulsion in the perforated layers or the curved IMDS in the sphere BCP structure. Schematic and molecular structure of PS-b-PTBOS Three different hierarchical structures of ΦH-in-L in PS202-b- PTBOS35 (a), ΦN-in-L in PS567-b-PTBOS24 (b), and ΦN-in-S in PS160-b-PTBOS126 (c). The LC symmetry breaking in b and c is due to the BCP microphase separation. Macromolecules, 2006, 39, 517-527; 2007, 40, 840-848; 2007, 40, 5095-5102. 2007 Submitted. TEM images of PS202-b-PTBOS35, PS567-b-PTBOS24 and PS160-b-PTBOS126.

  2. Complex hierarchical self-assembly templated by block copolymersChristopher Li, Drexel University, DMR 0239415 Education Under this grant, one Ph.D. student (Lingyu Li) and 1 master student (Steve Kodjie) and 2 undergraduate students graduated in 2006. Two graduate students are pursuing their Ph.D. degrees: Mr. Kishore Tenneti (going to graduate in 2007)) and Mr. Songqing Weng. One BS/MS student and two undergraduate students have also been supported. • Outreach • Coordinated the Drexel Summer Seed program for the department of Materials Science and Engineering at Drexel University. This program host ~200 high school students from nearby schools. • Conducted demo experiments which have consistently been evaluated as the “best lab” in the entire COE. The above image shows students from minority groups were enjoying making “slime and foams” in the polymer processing lab. • Hosted one NSF REU student in the summer for 10 weeks to conduct polymer research. • Participated a series of university-wide recruiting activities.

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