Exceptionally Ductile and Tough Biomimetic Artificial Nacre with Gas Barrier Function

Abstract

Synthetic mimics of natural high-performance structural materials have shown great and partly unforeseen opportunities for the design of multifunctional materials. For nacre-mimetic nanocomposites, it has remained extraordinarily challenging to make ductile materials with high stretchability at high fractions of reinforcements, which is however of crucial importance for flexible barrier materials. Here, highly ductile and tough nacre-mimetic nanocomposites are presented, by implementing weak, but many hydrogen bonds in a ternary nacre-mimetic system consisting of two polymers (poly(vinyl amine) and poly(vinyl alcohol)) and natural nanoclay (montmorillonite) to provide efficient energy dissipation and slippage at high nanoclay content (50 wt%). Tailored interactions enable exceptional combinations of ductility (close to 50% strain) and toughness (up to 27.5 MJ m ). Extensive stress whitening, a clear sign of high internal dynamics at high internal cohesion, can be observed during mechanical deformation, and the materials can be folded like paper into origami planes without fracture. Overall, the new levels of ductility and toughness are unprecedented in highly reinforced bioinspired nanocomposites and are of critical importance to future applications, e.g., as barrier materials needed for encapsulation and as a printing substrate for flexible organic electronics.

Glass Transition Temperature Regulates Mechanical Performance in Nacre‐Mimetic Nanocomposites

“…XRD confirms a well-ordered lamellar structure, and second-order diffraction peaks (2q*) of the primary peaks (q*) indicate a long-range order. [17,26,34,35] The amount of polymer (wt%) governs the nanoclay separation (d-spacing) as expected. Additional XRD measurements for nanocomposites with different copolymers reveal that the d-spacing depends strictly on the polymer content ( Figure S4, Supporting Information).…”

“…We focus on an established polymer/nanoclay nacre-mimetic system that delivers a highly reinforced (>50 wt% inorganics) lamellar nanocomposite. [17,26,28,29,32] The preparation of the nacremimetic nanocomposites starts with the synthesis of the energydissipative soft polymeric phase with a tunable T g . Following the procedure previously described by us, we synthesized six copolymers of poly(ethylene glycol methyl ether methacrylate-co-N,Ndimethylacrylamide) (EG x DMAm y ) with high water-solubility and non-ionic nature to prevent excessive changes in interactions with the nanoclay (Scheme 1a and Table 1).…”

Simultaneous Production and Functionalization of Boron Nitride Nanosheets by Sugar‐Assisted Mechanochemical Exfoliation

“…The homogeneous dispersion and the preferred alignment of BNNSs along the lateral direction (Figure d) may also contribute to these improvements. Note that there are many reports on other 2D nanofillers (e.g., graphene oxide (GO), reduced GO, nanoclay, layered double hydroxides (LDHs)) enhanced PVA composites with a tensile strength over 100 MPa, due to the strong interface interaction between these monolayered fillers and the polymer matrix. Compared with those fillers, the unique advantages of BNNS are that it is electrically insulating (better than GO and reduced GO), thermally conductive (better than nanoclay and LDHs), and chemically and thermally stable (better than LDHs).…”

Filter‐Through Method of Making Highly Efficient Polymer‐Clay Nanocomposite Membranes

“…Nanosheets of layered materials like clay (e.g., Na‐hectorite [Hec]), or graphene oxide (GO) are the most promising fillers for the fabrication of polymer nanocomposite barrier coatings . Barrier is of prime importance in applications spanning from automotive, furniture, construction, food, or optoelectronic packaging .…”

“…The novelty is based on the high-aspect ratio delaminated melt synthesized layered silicate (clay) [4] that is self-assembled in a polymer matrix as a barrier-layer between two electrospun membranes by filtration (filter-through method) and subsequently hot-pressed [5] which leads to enhanced gas-barrier properties.Nanosheets of layered materials like clay (e.g., Na-hectorite [Hec]), [6][7][8][9] or graphene oxide (GO) [10,11] are the most promising fillers for the fabrication of polymer nanocomposite barrier coatings. [12][13][14][15][16] Barrier is of prime importance in applications spanning from automotive, furniture, construction, food, or optoelectronic packaging. [13,14,[17][18][19] According to Cussler, the barrier improvement factor is nonlinearly dependent on both aspect ratio and filler content.…”