The effective dispersion and distribution of 1D (carbon nanotubes, CNTs) and 2D (graphene) nanomaterials in polymer melts has proven to be a non-trivial task. Irrespective of the mixing process used, if the thermodynamics of mixing are not favourable, then poor dispersion of the nanomaterial in the polymer matrix of interest results. This challenge can be further complicated by the strong nucleating effect that some 1D/2D nanomaterials can have on semi-crystalline polymers where the crystallisation kinetics and polymorphism of the polymer can be greatly altered. The properties of the interphase region between both components will be different to either the bulk polymer or nanomaterial, if for example, a trans-crystalline layer grows from the surface of the nanomaterial or if the formation of a nanohybrid shisk-kebab structure is favoured. The combined use of SAXS, WAXS, mechanical and thermal techniques has been used to investigate the morphology development in composites of poly(ethylene terephthalate) (PET) and multi-walled CNTs (MWCNTs). Good dispersion of 1D/2D nanomaterials in polymers can be obtained by promoting interfacial interactions with the polymer. Classically, this can be achieved via covalent functionalisation using a number of approaches, direct attachment of functional groups to the graphitic surface, or ‘grafting to’ or ‘grafting from’ strategies, all of which alter the intrinsic properties of the graphitic nanomaterial. Alternatively, the non-covalent functionalisation approach of using a polymer synthesized with specific properties and well-defined structures provides a route to functionalise CNTs via chain wrapping assisted by CH-π interactions. The role of multi-functional poly(acrylates) as modifiers and compatibilisers to promote interfacial interaction between MWCNTs or graphene with polypropylene (PP) was investigated. Poly(lauryl acrylate) wrapped and coated MWCNTs via CH-π interactions. 2-phenylethyl acrylate (2PEA) was synthesised as it allows π-π interaction with the surface of MWCNTs and graphene nano-platelets. Evidence for non-covalent interfacial interactions was obtained by comparing the electron energy loss near-edge fine structure (ENLES) of the carbon K-edge using high-resolution TEM of the block-copolymer bound to the surface of the MWCNTs. SAXS was used to probe the polymer filler interface and analysis confirmed the block-copolymer formed a regular lamella type structure on the MWCNT surface.

Interface and interphase in composites of polymers and 1D/2D nanomaterials

256th National Meeting (2018)

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