Prof. Sanat K. Kumar

Columbia University, NY, USA

Tuning Nanoparticle Dispersion in Polymer Hosts and their Consequences on Properties

Abstract

 

There is considerable on-going interest in controlling the spatial dispersion of nanoparticles (NP) in a polymer matrix to create materials with significantly improved properties. We begin with the idea that NPs grafted with polymer chains behave akin to surfactants and assemble into a variety of structures when they are placed in amorphous polymer hosts. The consequences of these different dispersion states on mechanical properties, especially how these results are affected by the glassiness of the matrix are probed next. We then explore the idea that it is easier to adsorb one block of a diblock copolymer onto the NP than chemically graft chains to the NPs. How these “grafted polymer mimics” affect properties and how these adsorbed structures are different from their grafted analogs is the second focus. Finally, we go beyond these equilibrium, surfactant-inspired paradigms and show that the isothermal crystallization rate of a polymer host can be used to dramatically vary NP spatial organization. The NPs, which are miscible with the polymer above its melting point, remain spatially well-dispersed when the polymer is crystallized at a rate that is fast relative to NP diffusion. In contrast, monolayer-thick NP sheets with intersheet spacing of (10100 nm) form in slowly crystallized samples. Since this NP self-assembly significantly improves the polymer’s mechanical properties, we conclude that crystal growth kinetics represents an underappreciated handle to tailor the NP spatial dispersion and hence the properties of this class of commercially relevant polymer nanocomposites.



Date: 18/9/2017
Time:12:00 (coffee & cookies will be served at 11:45)
Place:FORTH Seminar Room 1