@article{wei_gurr_gozen_blencowe_solomon_qiao_spontak_genzer_2008, title={Autophobicity-driven surface segregation and patterning of core-shell microgel nanoparticles}, volume={8}, ISSN={["1530-6992"]}, DOI={10.1021/nl802109x}, abstractNote={Core-shell microgel (CSMG) nanoparticles, also referred to as core-cross-linked star (CCS) polymers, can be envisaged as permanently cross-linked block copolymer micelles and, as such, afford novel opportunities for chemical functionalization, templating, and encapsulation. In this study, we explore the behavior of CSMG nanoparticles comprising a poly(methyl methacrylate) (PMMA) shell in molten PMMA thin films. Because of the autophobicity between the densely packed, short PMMA arms of the CSMG shell and the long PMMA chains in the matrix, the nanoparticles migrate to the film surface. They cannot, however, break through the surface because of the inherently high surface energy of PMMA. Similar thermal treatment of CSMG-containing PMMA thin films with a polystyrene (PS) capping layer replaces surface energy at the PMMA/air interface by interfacial energy at the PMMA/PS interface, which reduces the energy barrier by an order of magnitude, thereby permitting the nanoparticles to emerge out of the PMMA bulk. This nanoscale process is reversible and can be captured at intermediate degrees of completion. Moreover, it is fundamentally general and can be exploited as an alternative means by which to reversibly pattern or functionalize polymer surfaces for applications requiring responsive nanolithography.}, number={9}, journal={NANO LETTERS}, author={Wei, Bin and Gurr, Paul A. and Gozen, Arif O. and Blencowe, Anton and Solomon, David H. and Qiao, Greg G. and Spontak, Richard J. and Genzer, Jan}, year={2008}, month={Sep}, pages={3010–3016} }
 @article{wei_lam_braunfeld_agard_genzer_spontak_2006, title={Tunable instability mechanisms of polymer thin films by molecular self-assembly}, volume={22}, ISSN={["0743-7463"]}, DOI={10.1021/la061391j}, abstractNote={Incorporation of a block copolymer into a thin polymer film is observed to alter both the rate and mechanism by which the film dewets from an immiscible polymer substrate. Films with little or no copolymer dewet by classical nucleation and growth of circular holes, and the dewetting rate decreases with increasing copolymer concentration. Increasing the copolymer content at constant film thickness generates copolymer micelles that adsorb/aggregate along the polymer/polymer interface and promote nonclassical dewetting fluctuations similar in appearance to spinodal dewetting. At higher copolymer concentrations, dewetting proceeds after a lengthy induction period by the nucleation and growth of flower-shaped holes suggestive of film pinning or viscous fingering. Atomic force microscopy of the polymer/polymer interface after removal of the top film by selective dissolution reveals substantial structural development due to copolymer self-assembly.}, number={21}, journal={LANGMUIR}, author={Wei, Bin and Lam, Peter G. and Braunfeld, Michael B. and Agard, David A. and Genzer, Jan and Spontak, Richard J.}, year={2006}, month={Oct}, pages={8642–8645} }
 @article{wei_genzer_spontak_2004, title={Dewetting behavior of a block copolymer/homopolymer thin film on an immiscible homopolymer substrate}, volume={20}, ISSN={["0743-7463"]}, DOI={10.1021/la049562c}, abstractNote={Numerous previous studies have established that the addition of a microphase-ordered AB diblock copolymer to a thin homopolymer A (hA) film can slow, if not altogether prevent, film rupture and subsequent film dewetting on a hard substrate such as silica. However, only a few reports have examined comparable phenomena when the hA/AB blend resides on a soft B-selective surface, such as homopolymer B (hB). In this work, the dewetting kinetics of thin films composed of polystyrene (PS) and a symmetric poly(styrene-b-methyl methacrylate) (SM) diblock copolymer on a poly(methyl methacrylate) substrate is investigated by hot-stage light microscopy. Without the SM copolymer, the dewetting rate of the PS layer is constant under isothermal conditions and exhibits Arrhenius behavior with an apparent activation energy of approximately 180 kJ/mol. Addition of the copolymer promotes a crossover from early- to late-stage dewetting kinetics, as evidenced by measurably different dewetting rates. Transmission electron microscopy reveals the morphological characteristics of dewetted PS/SM films as functions of film thickness and SM concentration.}, number={20}, journal={LANGMUIR}, author={Wei, B and Genzer, J and Spontak, RJ}, year={2004}, month={Sep}, pages={8659–8667} }
 @article{wei_gurr_genzer_qiao_solomon_spontak_2004, title={Dewetting of star nanogel/homopolymer blends from an immiscible homopolymer substrate}, volume={37}, ISSN={["0024-9297"]}, DOI={10.1021/ma048636o}, abstractNote={Departments of Chemical & BiomolecularEngineering and Materials Science & Engineering,North Carolina State University,Raleigh, North Carolina 27695, and Polymer Science Group,Department of Chemical & Biomolecular Engineering,University of Melbourne, Victoria 3010, AustraliaReceived July 6, 2004Revised Manuscript Received August 26, 2004}, number={21}, journal={MACROMOLECULES}, author={Wei, B and Gurr, PA and Genzer, J and Qiao, GG and Solomon, DH and Spontak, RJ}, year={2004}, month={Oct}, pages={7857–7860} }