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Pattern-Directed Phase Separation of Polymer-Grafted Nanoparticles in a Homopolymer Matrix



Ren Zhang, Bongjoon Lee, Michael R. Bockstaller, Sanat K. Kumar, Christopher Stafford, Jack F. Douglas, Dharmaraj Raghavan, Alamgir Karim


The controlled organization of nanoparticle (NP) constituents into superstructures of well- defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We show that the phase separation of polymer-tethered nanoparticles immersed in a chemically different polymer matrix provides an effective and scalable method for fabricating submicron-sized NP domains in polymer thin films. We investigate this phenomenon with a view towards understanding and controlling the phase separation morphology using strategies in our earlier work on ordinary binary polymer blends. For the particular case of isothermal annealed thin films of polystyrene-grafted gold nanoparticles (AuPS) dispersed in poly(methyl methacrylate) (PMMA) matrix, a morphology transition from discrete AuPS domain structure to bicontinuous structure to inverse discrete domain structure is observed with increasing nanoparticle loading, which is in accordance with classic polymer blend phase separation. The kinetics of the AuPS/PMMA phase separation in these blends, however, shows some novel features in comparison to their counterpart homopolymer PS/PMMA blends. Furthermore, we exert morphological control via capillary force lithography (CFL) over the AuPS/PMMA blend films through the introduction of a symmetry breaking perturbation from the early stages of phase separation. This novel directed self-assembly method allows the controlled nanoparticle organization into nearly pure AuPS submicron-sized strip or cross-hatch lattice patterned domains over large areas. The synergy of phase separation and CFL in polymer tethered nanoparticle blend systems opens new possibilities to create patterned nanoparticle domains, thereby allowing for their potential applications as functional materials.


polymer blends, nanoparticles, phase separation, polymer brushes, morphology


Zhang, R. , Lee, B. , Bockstaller, M. , Kumar, S. , Stafford, C. , Douglas, J. , Raghavan, D. and Karim, A. (2016), Pattern-Directed Phase Separation of Polymer-Grafted Nanoparticles in a Homopolymer Matrix, Macromolecules, [online], (Accessed April 24, 2024)
Created May 11, 2016, Updated October 12, 2021