Modification of Polymer/Polymer Interfaces using Block Copolymers and Microgels

stamp;pattern;dewetting;polymer;Arrhenius;mechanism;heterogeneity;surface;interface;microgel;particle;autophobicity

Wei, Bin ; Jan Genzer, Committee Co-Chair,John van Zanten, Committee Member,Alan E. Tonelli, Committee Member,Richard J. Spontak, Committee Chair,Wei, Bin ; Jan Genzer ; Committee Co-Chair ; John van Zanten ; Committee Member ; Alan E. Tonelli ; Committee Member ; Richard J. Spontak ; Committee Chair

University:North Carolina State University

关键词: stamp;    pattern;    dewetting;    polymer;    Arrhenius;    mechanism;    heterogeneity;    surface;    interface;    microgel;    particle;    autophobicity;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/3262/etd.pdf?sequence=1&isAllowed=y

美国|英语

来源: null

【 摘 要 】

A guest macromolecular material, either a block copolymer (BCP) or core-shell microgel (MG) particles, has been used to stabilize a polystyrene (PS) film positioned atop an immiscible homopolymer substrate of poly(methyl methacrylate) (PMMA). Modification of the PS/PMMA interface due to interfacial partitioning of the guest macromolecule significantly increases the stability of the PS film by either slowing down or completely eliminating dewetting of the top PS layer.Our work has revealed that the dewetting mechanism of the top layer may change between nucleation and growth of holes and spinodal-like surface fluctuations, depending on the extent of interfacial heterogeneities induced by the BCP. Due to the shape retention of the MG, autophobicity is observed between the MG particles with a PS-like core and PMMA arms and a chemically identical long-chain PMMA homopolymer. This behavior is attributed to entropic exclusion of the PMMA matrix polymer from the PMMA arms of high graft density.We have demonstrated that autophobicity is strong enough to overcome the resistance of interfacial tension γAB so that the MG could be pushed from the PMMA matrix to the PS/PMMA interface, whereas the PMMA/MG surface remained free of MG, because the PMMA surface energy suppresses the surface roughening that accompanies autophobic segregation. Such MG-induced interfacial patterning in areas in contact with PS is completely reversible. Further annealing the PMMA/MG after the PS is removed permits the surface energy of PMMA to force the MG back into the PMMA substrate. Based on this reversible autophobic segregation, we have developed a simple stamping strategy of controlled and reversible patterning of MG particles on the film surface. A patterned poly(dimethyl siloxane) (PDMS) film with periodic ridges and valleys can be utilized as a stamp to control the in-plane distribution of the segregating MG particles. The MG blended in the PMMA/MG film migrates to the surface only in areas in contact with the PDMS. Further annealing with the stamp removed causes the film surface to smoothen due solely to surface tension.