Functional polymer nanocomposites incorporating Janus nanodimers

Polymer nanocomposites (PNCs) are materials composed of a polymer matrix incorporating particles with at least one dimension in the nanometer scale. These nanoparticles (NPs) can dramatically alter the mechanical, thermal, and rheological properties of the host phase and generate new properties to meet present and future demands in functional materials. Recent developments in the synthesis of NPs supplied a formidable collection of building blocks for the design of functional PNCs with limitless possibilities in strategic formulations for industry, such as coatings, paints, packaging, and personal care.

Predicting and controlling the macroscopic behaviour of PNCs relies on the full understanding of the physical phenomena that occur at the nanoscale and depend on properties intrinsic to the polymer (e.g. chemical structure and chain entanglements), properties intrinsic to the NPs (e.g. size, shape anisotropy and surface modifications), and properties resulting from the combination of both species (e.g. NPs’ distribution and NP/polymer interactions). It is perhaps the latter contribution that introduces a major extra challenge towards a full control on the performance of a PNC [1,2].

In the present project, we aim at exploring the feasibility of selectively tuning the NP/polymer interactions in order to achieve a more robust control on the material properties and its macroscopic response. To this end, we will investigate model PNCs consisting of functional NPs embedded in a diblock copolymer, a polymer comprising two homopolymer subunits. Due to the chemical incompatibility of their blocks, copolymers undergo microphase separation and self-assemble into a wide spectrum of hierarchical nanostructures, such as hexagonally packed, cubic and lamellar phases [3], which are particularly appealing to control the spatial arrangement of the NPs. Given its reduced viscosity as compared to other mesophases, the lamellar phase is of strategic interest in a number of industrial applications, such as coatings and thin films [4,5]. Depending on the strength of the interactions established between NPs and copolymer blocks, adding NPs to a lamellar phase can favour a very precise control on the viscosity of a PNC.

To test this hypothesis, by performing Molecular Dynamics simulation, we will determine the viscosity of the lamellar mesophases formed by an AB diblock copolymer incorporating functional NPs, such as Janus nanodimers (NDs). Janus NDs are particles with two chemically distinct spherical domains that can be selectively attracted by the copolymer block with similar chemical nature and repelled by the other. For comparison, we will also investigate the effect of neutral and A-like or B-like monofunctional NDs on the viscosity of the same polymer. With such an essential set of interactions, we will have an insight into the viscosity of functional PNCs when the NDs are (i) evenly distributed in the lamellar phase (neutral NDs); (ii) mostly distributed in the bulk of the layers consisting of A or B copolymer blocks (monofunctional NDs); and (iii) mostly distributed at the interface between layers of A and B blocks (Janus NDs).

The successful candidate will develop computational models to simulate the phase behaviour and dynamics of polymer melts incorporating NPs. The applicant should be familiar with programming and have a strong interest in learning how to employ MD software (e.g. DL_POLY, LAMMPS).

Applicants should have or expect to achieve at least a 2.1 honours degree in Physics, Chemical Engineering, Chemistry or a related subject.

Successful candidates will be enrolled in the 3-year Ph.D. program of the School of Chemical Engineering and Analytical Science.