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Adsorption and Surface Structure Characteristics Toward Polymeric Bottle-Brush Surfaces via Multiscale Simulation

Leuty, Gary M

Abstract Details

2014, Doctor of Philosophy, University of Akron, Polymer Science.
For decades, device design has focused on decreasing length scales. In computer and electronic engineering, small feature sizes allow increasing computational power in ever-smaller packages; in medicine, nanoscale in vivo devices and sensors and coatings have myriad applications. These applications all focus strongly on material/component interfaces. While recent advances in experimental techniques probing interfaces at nanometer and sub-nanometer scales have improved dramatically, computational simulation remains vital to obtaining detailed information about structure and energetics in nanometer-scale interactions at interfaces and the physical properties arising from interactions at larger scales. We start with all-atom molecular dynamics simulations of methane and chloromethane adsorption on the (100) surface of molybdenum to understand adsorbate polarity/geometry and substrate interaction potential effects on interfacial structure, packing and energetics. For featureless substrates, adsorbate geometry and orientation do not influence packing and affinity. Substrates with explicit surface structure show cooperation between substrate and adsorbate geometry via adsorption-site preference. Methane prefers sites over unit cell faces, roughly commensurate with the Mo surface, whereas chloromethane invites disorder, orienting its long axis along ”bridges” between surface Mo atoms. In the second phase, we used a coarse-grained bead-spring model to perform simulations of bottle-brush homopolymers tethered to a wall substrate at long time/length scales. We studied the intra- and intermolecular accumulation of tension in tethered bottle-brush backbones vs. bottle-brush dimensions and surface grafting density. Variations in bond force and bottle-brush/component shape and size descriptors uncovered three tension ”regimes”: (i) an isolated-brush regime (low surface grafting density), where intramolecular interactions dominate and tension is minimal; (ii) a ”soft-contact” regime, where neighboring bottlebrushes’ side chains overlap, compressing side chains and transmitting moderate tension to backbones; and (iii) a ”hard-contact” regime, where increased side-chain overlap forces reorientation, accumulating significant backbone tension. We then performed a small number of simulations of tethered bottle-brushes with two different side chain types to illustrate the morphologies available as a result of microphase separation, varying the strength of the interactions between side chain types. Continuing this work in the future should help discover other possible applications arising from varying the chemical nature of the side chains.
Mesfin Tsige, Dr. (Advisor)
Mark Foster , Dr. (Committee Member)
Shi-Qing Wang, Dr. (Committee Member)
Gustavo Carri, Dr. (Committee Member)
Jutta Luettmer-Strathmann, Dr. (Committee Member)
163 p.

Recommended Citations

Citations

  • Leuty, G. M. (2014). Adsorption and Surface Structure Characteristics Toward Polymeric Bottle-Brush Surfaces via Multiscale Simulation [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1397577080

    APA Style (7th edition)

  • Leuty, Gary. Adsorption and Surface Structure Characteristics Toward Polymeric Bottle-Brush Surfaces via Multiscale Simulation. 2014. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1397577080.

    MLA Style (8th edition)

  • Leuty, Gary. "Adsorption and Surface Structure Characteristics Toward Polymeric Bottle-Brush Surfaces via Multiscale Simulation." Doctoral dissertation, University of Akron, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1397577080

    Chicago Manual of Style (17th edition)