Polydispersity and Symmetry in Block Copolymers Mark Wrobleski, Case Western Reserve University

1. CMU REU: Materials Research – Summer 2008Greg S. Rohrer, Mohammad Islam, Carnegie Mellon University, DMR 0648976 Polydispersity and Symmetry in Block Copolymers Mark Wrobleski, Case Western Reserve University Jess Listak, Professor Michael Bockstaller, Carnegie Mellon University Experimental results have revealed the formation of a HPL (hexagonal perforated lamella) morphology in a polydisperse block copolymer (see figure). This observation is in contrast to theoretical predictions. The focus of this research project was to simulate molecular weight distributions (MWD) that result when polymers are synthesized using the ATRP technique (atom transfer radical polymerization) and to compare the skewness of those distributions to a Schulz-Zimm distribution, which forms the basis of theoretical studies. Initial results reveal that the MWD attainable by ATRP reactions is distinctly more symmetric (lower skewness) then predicted by a Schulz-Zimm distribution. This points to the relevance of symmetry of MWD as an additional parameter that determines microphase-separation in block copolymers. Simulated molecular weight distribution for an ATRP synthesized polymer. Panel a: (PS-PMA)NN: revealing C microstructure imaged along [001] direction. Inset depicts view along [100] direction. Panel b: (PS-PMA)NP: revealing HPL microstructure imaged at low magnification. The inset on the left depicts the PS-perforations within the PMA layers. The inset on the right shows a plane view revealing the hexagonal arrangement of the PS perforations. J. Listak, et al., Macromolecules, 2008 in press.

2. CMU REU: Materials Research – Summer 2008Greg S. Rohrer, Mohammad Islam, Carnegie Mellon University, DMR0648976 Summer Materials Research Program for Undergraduates This summer, 24 undergraduates participated in our summer research program. In the first week of the REU program, a lab safety course was taught along with a special seminar on research ethics. After five weeks, a symposium is held where all the students present brief oral reports on their project goals, progress to date, and plans for the second half of the summer. The summer concludes with final oral presentations in a second symposium; each student also produces a written summary and answers a questionnaire. The internship is also punctuated by additional education activities such a seminar series given by various faculty from the university.

3. CMU REU: Materials Research – Summer 2008 Greg S. Rohrer, Mohammad Islam, Carnegie Mellon University, DMR 0648976 On June 26-27, 2008, we held a two day workshop where teachers were invited to participate in presentations on how to use the archived educational materials. Based on the survey completed by the teachers attending the 2008 Summer Workshop, an estimated 745 additional students will be exposed to material science topics as a result of this summer experience. Participants of the 2008 Summer High School Workshop experienced a hands-on presentation on the materials properties of titanium based alloys and how they is used in the sports industry by Mr. Justin Sickles. Justin Sickles discusses his development of the project exploring the properties of titanium. Participants perform a compression test on a piece of titanium alloy tubing.