Abstract Fish scales inspired materials platform can provide advanced mechanical properties and functionalities. These materials, inspired from fish scales take the form of either composite materials or multi-material discrete exoskeleton type structures. Over the last decade, they have been under intense scrutiny for generating tailorable and tunable stiffness, penetration and fracture resistance, buckling prevention, nonlinear damping, hydrodynamic and camouflaging functions. Such programmable behavior emerges from leveraging their unique morphology and structure-property relationships. Several advanced tools of characterization, manufacturing, modeling and computation have been employed to understand and discover their behavior. With the rapid proliferation of additive manufacturing (AM) techniques, and advancing envelope of modeling and computational methods, this field is seeing renewed efforts to realize even more ambitious designs. We present a review and recapitulation of the state-of-the art in fish scale inspired materials in this paper.
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Super-soft, firm, and strong elastomers toward replication of tissue viscoelastic response
Polymeric networks are commonly used for various biomedical applications, from reconstructive surgery to wearable electronics. Some materials may be soft, firm, strong, or damping however, implementing all four properties into a single material to replicate the mechanical properties of tissue has been inaccessible. Herein, we present the A- g -B brush-like graft copolymer platform as a framework for fabrication of materials with independently tunable softness and firmness, capable of reaching a strength of ∼10 MPa on par with stress-supporting tissues such as blood vessel, muscle, and skin. These properties are maintained by architectural control, therefore diverse mechanical phenotypes are attainable for a variety of different chemistries. Utilizing this attribute, we demonstrate the capability of the A- g -B platform to enhance specific characteristics such as tackiness, damping, and moldability.
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- NSF-PAR ID:
- 10357002
- Date Published:
- Journal Name:
- Materials Horizons
- ISSN:
- 2051-6347
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Rare‐earth iron garnets (REIG) have recently become the materials platform of choice for spintronic studies on ferrimagnetic insulators. However, thus far the materials studied have mainly been REIG with a single rare earth species such as thulium, yttrium, or terbium iron garnets. In this study, magnetometry, ferromagnetic resonance, and magneto‐optical Kerr effect imaging is used to explore the continuous variation of magnetic properties as a function of composition for Y
x Tm3−x iron garnet (Yx Tm3−x IG) thin films grown by pulsed laser deposition on gadolinium gallium garnet substrates. It is reported that the tunability of the magnetic anisotropy energy, with full control achieved over the type of anisotropy (from perpendicular, to isotropic, to an in‐plane easy axis) on the same substrate. In addition, a nonmonotonic composition‐dependent anisotropy term is reported, which is ascribed to growth‐induced anisotropy similar to what is reported in garnet thin films grown by liquid‐phase epitaxy. Ferromagnetic resonance shows linear variation of the damping and the g‐factor across the composition range, consistent with prior theoretical work. Domain imaging reveals differences in reversal modes, remanant states, and domain sizes in Yx Tm3−x iron‐garnet thin films as a function of anisotropy. -
Herein, we present the direct modification of glucose, an abundant and inexpensive sugar molecule, to produce new sustainable and functional polymers. Glucose-6-acrylate-1,2,3,4-tetraacetate (GATA) has been synthesized and shown to provide a useful glassy component for developing an innovative family of elastomeric and adhesive materials. A series of diblock and triblock copolymers of GATA and n -butyl acrylate (n-BA) were created via Reversible Addition–Fragmentation Chain Transfer (RAFT) polymerization. Initially, poly(GATA)- b -poly(n-BA) copolymers were prepared using 4-cyano-4-[(ethylsulfanylthiocarbonyl)sulfanyl] pentanoic acid (CEP) as a chain transfer agent (CTA). These diblock copolymers demonstrated decomposition temperatures of 275 °C or greater and two glass transition temperatures ( T g ) around −45 °C and 100 °C corresponding to the PnBA and PGATA domains, respectively, as measured by differential scanning calorimetry (DSC). Triblock copolymers of GATA and n-BA, with moderate dispersities ( Đ = 1.15–1.29), were successfully synthesized when S , S -dibenzyl trithiocarbonate (DTC) was employed as the CTA. Poly(GATA)- b -poly(nBA)- b -poly(GATA) copolymers with 14–58 wt% GATA were prepared and demonstrated excellent thermomechanical properties ( T d ≥ 279 °C). Two well-separated glass transitions near the values for homopolymers of n-BA and GATA (∼−45 °C and ∼100 °C, respectively) were measured by DSC. The triblock with 14% GATA exhibited peel adhesion of 2.31 N cm −1 (when mixed with 30 wt% tackifier) that is superior to many commercial pressure sensitive adhesives (PSAs). Use of 3,5-bis(2-dodecylthiocarbonothioylthio-1oxopropoxy)benzoic acid (BTCBA) as the CTA provided a more efficient route to copolymerize GATA and n-BA. Using BTCBA, poly(GATA)- b -poly(nBA)- b -poly(GATA) triblock copolymers containing 12–25 wt% GATA, with very narrow molar mass distributions ( Đ ≤ 1.08), were prepared. The latter series of triblock copolymers showed excellent thermal stability with T d ≥ 275 °C. Only the T g for the PnBA block was observed by DSC (∼−45 °C), however, phase-separation was confirmed by small-angle X-ray scattering (SAXS) for all of these triblock copolymers. The mechanical behavior of the polymers was investigated by tensile experiments and the triblock with 25% GATA content demonstrated moderate elastomeric properties, 573 kPa stress at break and 171% elongation. This study introduces a new family of glucose-based ABA-type copolymers and demonstrates functionality of a glucose-based feedstock for developing green polymeric materials.more » « less
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Kareh, Kristina (Ed.)Mechanical metamaterials at the microscale exhibit exotic static properties owing to their en- gineered building blocks, but their dynamic properties have remained significantly less explored. Their design principles can target frequency-dependent properties and resilience upon high-strain-rate deformation, making them versatile materials for applications in lightweight impact resistance, acoustic waveguiding, or vibration damping. However, accessing dynamic properties at small scales has remained a challenge due to low-throughput and destructive characterization, or lack of existing testing protocols. Here we demonstrate a high-throughput non-contact framework that employs MHz-wave propagation signatures within a metamaterial to nondestructively extract dynamic linear properties, omnidirectional elastic information, damping properties, and defect quantification. Using rod-like tessellations of microscopic metamaterials, we report up to 94% direction- and rate-dependent dynamic stiffening at strain rates approaching 10^2 s^{−1}, in addition to damping properties 3 times higher than their constituent materials. We also show that frequency shifts in the vibrational response allow for characterization of invisible defects within the metamaterials, and that selective probing allows for construction of experimental elastic surfaces, previously only possible computationally. Our work provides a route for accelerated data-driven discovery of materials and microdevices for dynamic applications such as protective structures, medical ultrasound, or vibration isolation.more » « less
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Abstract The creep and recovery and the stress relaxation behaviors of poly(butylene adipate‐co‐terephthalate) (PBAT) and polyhydroxyalkanoates (PHA) binary blends incorporating 30 wt % of a mixture of trisilanolisobutyl polyhedral oligomeric silsesquioxanes (POSS) and calcium phosphate glass (CaP‐g) were investigated under simulated physiological and human body temperature conditions. The synergistic effect of PHA and CaP‐g/POSS filler remarkably improved the creep behavior of the PBAT matrix and decreased its residual strain, consequently enhancing its elastic recovery. A considerable increase of the relaxation modulus of the hybrid materials was also observed upon incorporation of PHA and CaP‐g/POSS. The relaxation modulus of the neat PBAT sample increased from ~60 MPa to ~1600 MPa after addition of 30 wt % CaP‐g/POSS and 70 wt % PHA. However, after exposure of the composites to the simulated human body conditions for 14 days, a drop of dynamic mechanical properties of the studied material systems was observed along with formation of a desirable calcium phosphate phase on the material surface. The long‐term (i.e., up to 7 × 105 s) viscoelastic behavior of the studied materials was successfully predicted using the time–temperature superposition principle and the obtained creep strain and the relaxation modulus master curves were satisfactorily fitted to the Findley power law equation and the generalized Maxwell model, respectively. This study demonstrates a facile method for tailoring CaP‐g/POSS bioactive glasses composition for bone‐like apatite formation on biopolymer surfaces. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2419–2432, 2019.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D2MH00844K
