UV‐Cured, Flexible, and Transparent Nanocomposite Coating with Remarkable Oxygen Barrier

Abstract

A polymer-layered silicate nanocomposite coating is prepared by combining a novel synthetic lithium-hectorite and an UV-curable, cationic polyurethane. Oxygen transmission measurements clearly indicate the supremacy of the lithium-hectorite as compared to a standard montmorillonite. In addition, a very high degree of optical transparency of the nanocomposite coating is achieved, rendering this material highly interesting for flexible packaging and encapsulation applications.

Nacre-mimetics with synthetic nanoclays up to ultrahigh aspect ratios

“…Such permeability values are better than the commercially available barrier films based on synthetic polymers such as polyvinyl chloride, polyvinyl alcohol, polyethylene terephthalate 69 and even highly oriented ethyl vinyl alcohol at similar humidity 70 . In fact the gas barrier is amongst the best ever reported values for layered clay materials-found here in a self-standing material at 80 %RH 27,31,32,34,37,54 . Therefore, the unique combination of transparency, gas barrier, and mechanical robustness make these rapidly prepared self-standing nanocomposite films a choice for food packaging, gas storage applications, and as sealants and advanced substrates for flexible organic electronics.…”

“…Although being outstanding in terms of oxygen barrier properties, the films demonstrate poor mechanical properties exhibiting tensile strength of only around 25 MPa 27,28 . In addition, sequential LbL of different nanoclays and polymers as ultrathin surface coatings revealed an extraordinary performance, and large hopes arise from new synthetic clays with highest aspect ratios 31,54 . However, the LbL method ultimately faces clear limitations when aiming at higher coating thicknesses or even self-standing films.…”

“…Two dimensional (2D) clay nanosheets are among the most interesting building blocks to realize these outstanding challenges owing to their high interface, nanoscale dimensions and tunable aspect ratio. Previous reports mostly concentrated on individual functional properties, such as gas barrier 27,[31][32][33][34][35][36][37] , fire shields [35][36][37][38][39] and photothermal activity 25 while still often falling short of addressing and realizing multifunctional property profiles with best and optimized performance in different areas.…”

Quasi-epitaxial Growth of [Ru(bpy)3]2+by Confinement in Clay Nanoplatelets Yields Polarized Emission

“…A simple doctorblade process from suspension with subsequent drying is suffi cient to retrieve highly textured composite fi lms of the functional nanoplatelets. [ 32 ] Moreover, packing of sensitive emitters by the perfectly transparent inorganic nanoplatelets might offer the additional benefi t of stabilizing and protecting the emitters against oxidation and hydrolysis and thus, increasing the lifetime of an optoelectronic device. Composites manufactured applying the same clay nanoplatelets, though not loaded with emitter guest molecules, have been shown to provide very high gas barrier activity.…”

Gas barrier properties of bio-inspired Laponite–LC polymer hybrid films

“…This phenomenon has been already observed in the literature for different composite systems, for example, by replacing Laponite clay platelets (diameter:thickness ∼25:1) [45] by MMT (∼200:1, polydisperse) [47], or vermiculite (∼1100:1) [37] clay platelets [36,37,43,[48][49][50]. By using high aspect ratio clay platelets and applying our bio-inspired LC concept onto MMT or vermiculite platelets, the resulting bioinspired clay/LC polymer composite coatings may potentially exhibit advanced gas barrier properties, comprising advantageous features such as high inorganic clay contents of >80%, stacking of the clay platelets comparable to natural nacre after particle exfoliation, and the liquid crystallinity of the polymeric matrix.…”