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Directed Assembly of Block Copolymer Films Via Surface Energy Tunable Elastomers

Hayirlioglu, Arzu
http://rave.ohiolink.edu/etdc/view?acc_num=akron1399049231

Abstract Details

2014, Doctor of Philosophy, University of Akron, Polymer Engineering.
Ordering of block copolymer (BCP) thin films has been great interest for potential applications due to nanometer scale size self-assembly pattern formation. Numerous methods (chemical, physical, etc.) have been developed to create desired alignment and ordering properties in such block copolymer systems. However, the drawback of most current technologies such as brittleness and lack conformability to different surfaces makes them difficult to implement new emerging high-tech flexible technologies. On the other hand, there is a lack of knowledge in block copolymer wettability characteristics and morphological behavior on soft substrates which makes them attractive to explore for further investigations. A notable challenge in this regard is that successful deployment of BCPs for applications requires an understanding of BCP ordering properties on flexible substrate as a function of their surface chemistry, topography including patterning, roughness, stiffness, modulus and thermal conductivity, etc. Therefore, the general purpose of this research is to investigate the thermodynamics and kinetics of directed assembly of cylinder and lamellar forming polystyrene-block-polymethlymethacrylate (PS-b-PMMA) diblock copolymer films on elastomeric polydimethylsiloxane (PDMS) substrates with controlled surface energy and substrate topography. In first part, wettability characteristics of cylinder and lamellae forming PS-b-PMMA thin films versus surface energy of elastomeric PDMS substrates were increasing surface energy of PDMS by tuning with Ultraviolet Ozone (UVO) exposure and elasticity by varying the crosslinking concentration. In this extended wetting regime gradual perpendicular to parallel orientation change was shown for lamellar BCP films unlike cylindrical films where the transition was very sharp, reflecting lamellar BCP intrinsic stability over a wider range of substrate surface energy, consistent with theoretical estimates. In second part of the study, we extended the part on wettability characteristics of polystyrene (PS) homopolymer and PS-b-PMMA block copolymer thin films on flat, periodic and non-periodic nanopatterned elastomeric PDMS substrates. We discovered creating non-periodically nanopatterned surface properties induced retardation of BCP dewetting and mostly eliminate on periodically nanopatterned surface properties without any surface chemistry modification. Time kinetic study results also showed the patterning has a slowing down effect on dewetting mechanism for both homopolymer and block copolymer systems and dewetted droplet shape. In final part of this study, we focused on block copolymer morphology on periodically and non-periodically (rough) patterned elastomeric PDMS substrates with and without tuning the substrate surface energy via UVO exposure. The regular uniform film properties were achieved with parallel or perpendicular microdomain orientation to the substrate at even imcommensurate thicknesses which normally shows island and holes on flat surfaces. In addition to the bottom pattern confinement effect on BCP ordering, uniform size patterned elastomeric top capping layer was also used. Mixed or long range ordered structures were obtained with different annealing conditions.
Alamgir Karim, Dr. (Advisor)
Mukerrem Cakmak, Dr. (Committee Member)
Matthew Becker, Dr. (Committee Member)
Kevin Cavicchi, Dr. (Committee Member)
Jutta Luettmer-Strathmann, Dr. (Committee Member)
138 p.
Polymers
Block copolymer; elastomers; PDMS; PS-PMMA; orientation, flexible substrates; dewetting

Recommended Citations

Citations

  • Hayirlioglu, A. (2014). Directed Assembly of Block Copolymer Films Via Surface Energy Tunable Elastomers [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399049231

    APA Style (7th edition)

  • Hayirlioglu, Arzu. Directed Assembly of Block Copolymer Films Via Surface Energy Tunable Elastomers . 2014. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1399049231.

    MLA Style (8th edition)

  • Hayirlioglu, Arzu. "Directed Assembly of Block Copolymer Films Via Surface Energy Tunable Elastomers ." Doctoral dissertation, University of Akron, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399049231

    Chicago Manual of Style (17th edition)

akron1399049231
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This open access ETD is published by University of Akron and OhioLINK.