Hierarchical Nacre Mimetics with Synergistic Mechanical Properties by Control of Molecular Interactions in Self‐Healing Polymers

Abstract

Designing the reversible interactions of biopolymers remains ag rand challenge for an integral mimicry of mechanically superior biological composites.Y et, they are the key to synergistic combinations of stiffness and toughness by providing sacrificial bonds with hidden length scales.T o address this challenge,d ynamic polymers were designed with low glass-transition temperature T g and bonded by quadruple hydrogen-bonding motifs,a nd subsequently assembled with high-aspect-ratio synthetic nanoclays to generate nacre-mimetic films.The high dynamics and self-healing of the polymers render transparent films with anear-perfectly aligned structure. Varying the polymer composition allows molecular control over the mechanical properties up to very stiff and very strong films (E % 45 GPa, s UTS % 270 MPa). Stable crack propagation and multiple toughening mechanisms occur in situations of balanced dynamics,e nabling synergistic combinations of stiffness and toughness.E xcellent gas barrier properties complement the multifunctional property profile.Inthe last decade,t he nacreous layer of mollusks has received enormous attention for its extraordinary combination of stiffness,t oughness,a nd strength.[1] Nacre contains 95 vol %a ragonite microtablets,w hich are laminated by ac omplex matrix of biopolymers containing silk fibroins, chitin nanofibrils,a nd ar ange of fusion proteins in ab rickand-mortar architecture.T he structure of the soft part guides the layered growth, and provides toughness by plastic deformation, frictional sliding and molecular energy-dissipation (for example,unfolding of secondary motifs).Such natural high-performance materials inspire synthetic bioinspired nanocomposites (NCs). Those contrast traditional NCs,b ya iming at highly ordered structures at high levels of reinforcements,a nd at best mimicking the complexity of the natural biopolymers with molecularly controlled strengthening and energy-dissipation mechanisms.There has been ar ange of approaches to mimic nacre, [1d] most notably sequential deposition of platelets and polymers, [2] or ice templating and sintering of ceramics,f ollowed by resin infusion.[3] We developed av ery efficient colloidal pathway to mimic the brick-and-mortar structure by selfassembly of polymer-coated (core-shell) nanoclay platelets.

A Bioinspired Ultratough Multifunctional Mica-Based Nanopaper with 3D Aramid Nanofiber Framework as an Electrical Insulating Material

“…For platelet/polymer nacre-mimetics, their polymer matrix materials have large ductility, but the strain-to-failure ratios are far less than 1, thereby leading to their brittleness. The low strain-to-failure ratios are ascribed to the nanoconfinement of polymer interlayer within the nanoscale gap between inorganic platelets. , For platelet/nanofiber nacre-mimetics, the strain-to-failure ratios fluctuate around 1, but their nanofiber matrix materials have low ductility. Differently, the bioinspired NTS/ANF-X 40/60 nanopaper has a high strain-to-failure ratio, obviously larger than 1, and its matrix material has a moderate ductility.…”

Linear shear and nonlinear extensional rheology of unentangled supramolecular side-chain polymers

“…Supramolecular polymers based on UPy groups have been widely investigated and materials with important characteristics such as stimuli-responsive [23], self-healing [10,11,[49][50][51][52] and temperature responsive [53,54] properties have found applications within printing [55][56][57][58], cosmetics [59,60], adhesives [61] and coatings [62]. As an example of how supramolecular associations can play an important role, for inkjet printing applications a UPy-modified polyether mixed with stabilizers, antioxidants and colourants was used in work by Jaeger et al [55].…”

Bioinspired Interfacial Chelating-like Reinforcement Strategy toward Mechanically Enhanced Lamellar Materials

“…Strong, tough, and lightweight composites have attracted extensive attention, as they are promising engineering materials for future aerospace, automotive industry, tissue engineering, protection, and electronics applications. − However, realization of the synthetic structural materials that allow the transfer of an excellent mechanical balance ( e . g ., high strength, excellent Young’s modulus, and fine crack propagation resistance) from the nanoscale to the macroscale of bulk materials still remains a significant challenge. − Surprisingly, nature uses its fascinating ways to produce lightweight, strong, and tough materials with complex, hierarchical architectures by directed self-assembly of hard/soft constituents, such as the prismatic layers of mollusk shells and teeth, the plywood fiber architecture of fish scales, insects, crustanceans, or plants, the concentric plywood structures around bone osteons and in wood cell walls, and the “brick-and-mortar” (BM) and cross-lamellar arrangements of mollusk shells. All of these possess an outstanding loading transfer from the nano- to the macroscale. − These reinforcing strategies rely on the intricate interplay by exquisite control over the local biochemical composition and the structure at multilevel scales, referring to the mechanical interlocking, mutual friction, molecular attraction, or sacrificing chemical bonds at hybrid interfaces when a biomaterial suffers from a heavy static/dynamic load. ,− With respect to these biomolecular compositions in these biomaterials, it has been found that several cross-linkers ( e .…”