Defect evolution in diblock copolymer films Lee Y. Park, Williams College, DMR 0922400

1. Defect evolution in diblock copolymer filmsLee Y. Park, Williams College, DMR 0922400 This multi-user instrument MRI grant was used to fund the purchase of two Agilent AFM at Williams College. These AFMs are being used in both research and teaching in multiple departments. A highlight from Ward Lopes’ research is provided here (physics. ) The Lopes lab is studying weakly segregated diblock copolymer systems with striped (smectic) symmetry, tracking defects as a function of time and temperature. to better understand pattern formation and evolution. They have found that disclinations Annihilation of dipole configuration of disclinations. Images are separated by 20 minute intervals. The scale bar is 300 nm long. The first image indicates a +1/2 disclination (red circle) and a -1/2 disclination (yellow circle). The Burgers vector for the configuration of the two disclinations (the sum of the red and yellow arrows) is the green vector with magnitude 6 repeat spacings in the second image. in weakly segregated, cylindrical phase, PS-b-PMMA diblock copolymers primarily annihilate in dipole configurations (one disclination with positive winding number and one disclination with negative winding number). These preliminary results are the first experimental evidence that the dynamics of ordering in different systems with the same smectic symmetry can be different. In future work, they will quantify the relative frequency of dipole, tripole and quadrupole annihilations in this diblock copolymer system. The observation of a dipole annihilation with a Burgers vector of magnitude 6 repeat spacings is shown above. Individual dislocations created by the annihilation are indicated in the second image. By time of the scan of the third image, most of the dislocations from the dipole annihilation have annihilated with other dislocations from outside of the image boundaries.

2. Acquisition of AFM systemsLee Y. Park, Williams College, DMR 0922400 All of the research at Williams College is carried out by undergraduate research assistants. To date there have been ~ 15 students from different labs (chemistry, physics, biology, computer science) trained in the use of the AFM for a broad range of applications, In addition, the AFM will be used extensively in a Materials Chemistry course in the Fall of 2010. A new set of laboratory experiments for an upper level chemistry course (Chemistry of Materials, Chem 336) focusing on tools and strategies for nanofabrication has been developed and will be offered in the fall of 2010. We have also begun planning for a professional development course (to be offered for the first time during the summer of 2011) for community college, high school, and middle school teachers that will focus on modern microscopy methods. The course will be designed as a 3- or 5-day workshop, with hands-on time on a variety of imaging instruments available at the college, including AFM, SEM, TEM, fluorescence microscopy, confocal microscopy, polarizing microscopy. Finally, we have worked with another group of undergraduates during the summer of 2010, under the auspices of the Williams Instructional Technology (WIT) program; these students have been designing and implementing an on-line instrument sign-up system that will facilitate the many users and parts associated with the AFMs on campus (and will also be extended to other shared equipment on campus.) This system will be operational by the end of summer 2010.