Boron nitride nanosheets as barrier enhancing fillers in melt processed composites

Abstract

In this work we have used melt-processing to mix liquid-exfoliated boron-nitride nanosheets with PET to produce composites for gas barrier applications. Sonication of h-BN powder, followed by centrifugation-based size-selection, was used to prepare suspensions of nanosheets with aspect ratio >1000. The solvent was removed to give a weakly aggregated powder which could easily be mixed into PET, giving a composite containing well-dispersed nanosheets. These composites showed very good barrier performance with oxygen permeability reductions of 42% by adding just 0.017 vol% nanosheets. At low loading levels the composites were almost completely transparent. At higher loading levels, while some haze was introduced, the permeability fell by ∼70% on addition of 3 vol% nanosheets.

Photoluminescence from Liquid‐Exfoliated WS2Monomers in Poly(Vinyl Alcohol) Polymer Composites

“…This is particularly problematic for high aspect ratio 2D fillers which can show aggregation effects even at loading levels below 0.5%. 45,46,50,51 Such aggregation is almost always detrimental to the properties of the composite, for example resulting in fall off in mechanical properties. 46 Alternatively for optical applications, well defined properties associated with monolayers might be required which would be destroyed by aggregation.…”

“…Under normal circumstances, such high filler loading would generally lead to aggregation during drying. 50 However, composite formation by freeze-drying should result in reduced aggregation.…”

Relating the optical absorption coefficient of nanosheet dispersions to the intrinsic monolayer absorption

“…Nanosheet suspensions (a.k.a. dispersions or inks) have been shown to be ideally suited to production of printed electronics 9,10 , including devices such as LEDs, battery and supercapacitor electrodes [11][12][13][14][15][16] , photo-detectors 17 and hydrogen evolution catalysis [18][19][20][21][22] , as well as additives in composites [23][24][25][26] . While the production of these dispersions can be scaled to industrial levels 8 , methods to reliably and rapidly characterise the material produced are limited.…”

Exploring the versatility of liquid phase exfoliation: producing 2D nanosheets from talcum powder, cat litter and beach sand

“…9,21 The resultant dispersions can very easily be processed into nanostructured materials by a range of methods such as spray casting, 22 inkjet printing, 23,24 gravure printing 25 and freeze drying. 26 These structures have been used in a wide range of applications from barrier composites 27,28 to battery electrodes 29,30 to photodetectors. 31,32 Importantly, LPE has been applied to a wide range of 2D materials including graphene, [33][34][35] 49 The large number of layered materials which have been exfoliated to nanosheets using LPE suggests an impressive degree of versatility.…”