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Bowser BH, Ho CH, Craig SL. High Mechanophore Content, Stress-Relieving Copolymers Synthesized via RAFT Polymerization. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01792] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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52
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Lin Y, Hansen HR, Brittain WJ, Craig SL. Strain-Dependent Kinetics in the Cis-to-Trans Isomerization of Azobenzene in Bulk Elastomers. J Phys Chem B 2019; 123:8492-8498. [PMID: 31525921 DOI: 10.1021/acs.jpcb.9b07088] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The cis-to-trans isomerization of azobenzene is accelerated in a bulk PDMS elastomer under uniaxial tension. The kinetics are cleanly described by a single-exponential first-order process (k = 2.7 × 10-5 s-1) in the absence of tension but become multiexponential under constant strains of 40-90%. The complex kinetics can be reasonably modeled as a two-component process. The majority (∼92%) process is slower and occurs with a rate constant that is similar to that of the unstrained system (k = 2.3-2.7 × 10-5 s-1), whereas the rate constant of the minority (∼8%) process increases from k = 10.1 × 10-5 s-1 at 40% strain to k = 21.3 × 10-5 s-1 at 90% strain. Simple models of expected force-rate relationships suggest that the average force of tension per strand in the minority component ranges from 28 to 44 pN across strains of 40-90%.
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Craig SL, Gault VA, McClean S, Hamscher G, Irwin N. Effects of an enzymatically stable C-terminal hexapseudopeptide fragment peptide of xenin-25, ψ-xenin-6, on pancreatic islet function and metabolism. Mol Cell Endocrinol 2019; 496:110523. [PMID: 31352038 DOI: 10.1016/j.mce.2019.110523] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 06/18/2019] [Accepted: 07/24/2019] [Indexed: 12/19/2022]
Abstract
Xenin-25 undergoes rapid enzyme metabolism following secretion. Early studies demonstrated bioactivity of a C-terminal hexapeptide fragment of xenin-25, namely xenin-6, which were enhanced through introduction of a reduced N-terminal peptide bond, to yield Ψ-xenin-6. The present study was undertaken to define the biological actions and potential antidiabetic properties of Ψ-xenin-6. In vitro enzymatic stability, insulin and glucagon secretory activity, as well as effects on beta-cell survival were determined. Studies in mice were used to assess the impact of Ψ-xenin-6 on glucose homeostasis and satiety. Ψ-xenin-6 was resistant to murine plasma degradation. In BRIN-BD11 cells and isolated murine islets, Ψ-xenin-6 significantly stimulated insulin secretion, and prominently enhanced the insulinotropic actions of GIP. Xenin-6 and Ψ-xenin-6 had no impact on glucagon secretion, although xenin-6 partially reversed the glucagonotropic action of GIP. Further in vitro investigations revealed that, similar to GLP-1, Ψ-xenin-6 significantly augmented proliferation of human and rodent clonal beta-cells, whilst also fully protecting against cytokine-induced beta-cell cytotoxicity, with greater potency than xenin-25 and xenin-6. When administered to mice in combination with glucose, Ψ-xenin-6 significantly reduced glucose levels and enhanced glucose-induced insulin release, with a duration of biological action beyond 8 h. Ψ-xenin-6 also significantly enhanced the glucose-lowering action of GIP in vivo. In overnight fasted mice, Ψ-xenin-6 exhibited satiety actions at both 25 and 250 nmol/kg. These data demonstrates that Ψ-xenin-6 is a metabolically stable C-terminal fragment analogue of xenin-25, with a metabolic action profile that merits further study as a potential antidiabetic compound.
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Lin TS, Coley CW, Mochigase H, Beech HK, Wang W, Wang Z, Woods E, Craig SL, Johnson JA, Kalow JA, Jensen KF, Olsen BD. BigSMILES: A Structurally-Based Line Notation for Describing Macromolecules. ACS CENTRAL SCIENCE 2019; 5:1523-1531. [PMID: 31572779 PMCID: PMC6764162 DOI: 10.1021/acscentsci.9b00476] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Indexed: 05/21/2023]
Abstract
Having a compact yet robust structurally based identifier or representation system is a key enabling factor for efficient sharing and dissemination of research results within the chemistry community, and such systems lay down the essential foundations for future informatics and data-driven research. While substantial advances have been made for small molecules, the polymer community has struggled in coming up with an efficient representation system. This is because, unlike other disciplines in chemistry, the basic premise that each distinct chemical species corresponds to a well-defined chemical structure does not hold for polymers. Polymers are intrinsically stochastic molecules that are often ensembles with a distribution of chemical structures. This difficulty limits the applicability of all deterministic representations developed for small molecules. In this work, a new representation system that is capable of handling the stochastic nature of polymers is proposed. The new system is based on the popular "simplified molecular-input line-entry system" (SMILES), and it aims to provide representations that can be used as indexing identifiers for entries in polymer databases. As a pilot test, the entries of the standard data set of the glass transition temperature of linear polymers (Bicerano, 2002) were converted into the new BigSMILES language. Furthermore, it is hoped that the proposed system will provide a more effective language for communication within the polymer community and increase cohesion between the researchers within the community.
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Perry RA, Craig SL, Ng MT, Gault VA, Flatt PR, Irwin N. Characterisation of Glucose-Dependent Insulinotropic Polypeptide Receptor Antagonists in Rodent Pancreatic Beta Cells and Mice. CLINICAL MEDICINE INSIGHTS-ENDOCRINOLOGY AND DIABETES 2019; 12:1179551419875453. [PMID: 31548798 PMCID: PMC6743192 DOI: 10.1177/1179551419875453] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 08/21/2019] [Indexed: 12/18/2022]
Abstract
Hypersecretion and alterations in the biological activity of the incretin
hormone, glucose-dependent insulinotropic polypeptide (GIP), have been
postulated as contributing factors in the development of obesity-related
diabetes. However, recent studies also point to weight-reducing effects of GIP
receptor activation. Therefore, generating precise experimental tools, such as
specific and effective GIP receptor (GIPR) antagonists, is of key significance
to better understand GIP physiology. Thus, the primary aim of the current study
was to uncover improved GIPR antagonists for use in rodent studies, using human
and mouse GIP sequences with N- and C-terminal deletions. Initial in
vitro studies revealed that the GIPR agonists, human (h) GIP(1-42),
hGIP(1-30) and mouse (m) GIP(1-30), stimulated (P < 0.01 to
P < 0.001) insulin secretion from rat BRIN-BD11 cells.
Analysis of insulin secretory effects of the N- and C-terminally cleaved GIP
peptides, including hGIP(3-30), mGIP(3-30), h(Pro3)GIP(3-30),
hGIP(5-30), hGIP(3-42) and hGIP(5-42), revealed that these peptides did not
modulate insulin secretion. More pertinently, only hGIP(3-30), mGIP(3-30) and
h(Pro3)GIP(3-30) were able to significantly (P
< 0.01 to P < 0.001) inhibit hGIP(1-42)-stimulated
insulin secretion. The human-derived GIPR agonist sequences, hGIP(1-42) and
hGIP(1-30), reduced (P < 0.05) glucose levels in mice
following conjoint injection with glucose, but mGIP(1-30) was ineffective. None
of the N- and C-terminally cleaved GIP peptides affected glucose homeostasis
when injected alone with glucose. However, hGIP(5-30) and mGIP(3-30)
significantly (P < 0.05 to P < 0.01)
impaired the glucose-lowering action of hGIP(1-42). Further evaluation of these
most effective sequences demonstrated that mGIP(3-30), but not hGIP(5-30),
effectively prevented GIP-induced elevations of plasma insulin concentrations.
These data highlight, for the first time, that mGIP(3-30) represents an
effective molecule to inhibit GIPR activity in mice.
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Barbee MH, Wang J, Kouznetsova T, Lu M, Craig SL. Mechanochemical Ring-Opening of Allylic Epoxides. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01190] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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57
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Lin Y, Zhang Y, Wang Z, Craig SL. Dynamic Memory Effects in the Mechanochemistry of Cyclic Polymers. J Am Chem Soc 2019; 141:10943-10947. [DOI: 10.1021/jacs.9b03564] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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58
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Park J, Lee Y, Barbee MH, Cho S, Cho S, Shanker R, Kim J, Myoung J, Kim MP, Baig C, Craig SL, Ko H. A Hierarchical Nanoparticle-in-Micropore Architecture for Enhanced Mechanosensitivity and Stretchability in Mechanochromic Electronic Skins. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1808148. [PMID: 31070272 DOI: 10.1002/adma.201808148] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/16/2019] [Indexed: 06/09/2023]
Abstract
Biological tissues are multiresponsive and functional, and similar properties might be possible in synthetic systems by merging responsive polymers with hierarchical soft architectures. For example, mechanochromic polymers have applications in force-responsive colorimetric sensors and soft robotics, but their integration into sensitive, multifunctional devices remains challenging. Herein, a hierarchical nanoparticle-in-micropore (NP-MP) architecture in porous mechanochromic polymers, which enhances the mechanosensitivity and stretchability of mechanochromic electronic skins (e-skins), is reported. The hierarchical NP-MP structure results in stress-concentration-induced mechanochemical activation of mechanophores, significantly improving the mechanochromic sensitivity to both tensile strain and normal force (critical tensile strain: 50% and normal force: 1 N). Furthermore, the porous mechanochromic composites exhibit a reversible mechanochromism under a strain of 250%. This architecture enables a dual-mode mechanochromic e-skin for detecting static/dynamic forces via mechanochromism and triboelectricity. The hierarchical NP-MP architecture provides a general platform to develop mechanochromic composites with high sensitivity and stretchability.
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Sha Y, Zhang Y, Xu E, McAlister CW, Zhu T, Craig SL, Tang C. Generalizing metallocene mechanochemistry to ruthenocene mechanophores. Chem Sci 2019; 10:4959-4965. [PMID: 31183044 PMCID: PMC6526481 DOI: 10.1039/c9sc01347d] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 04/26/2019] [Indexed: 12/15/2022] Open
Abstract
Recent reports have shown that ferrocene displays an unexpected combination of force-free stability and mechanochemical activity, as it acts as the preferred site of chain scission along the backbone of highly extended polymer chains. This observation raises the tantalizing question as to whether similar mechanochemical activity might be present in other metallocenes, and, if so, what features of metallocenes dictate their relative ability to act as mechanophores. In this work, we elucidate polymerization methodologies towards main-chain ruthenocene-based polymers and explore the mechanochemistry of ruthenocene. We find that ruthenocene, in analogy to ferrocene, acts as a highly selective site of main chain scission despite the fact that it is even more inert. A comparison of ruthenocene and ferrocene reactivity provides insights as to the possible origins of metallocene mechanochemistry, including the relative importance of structural and thermodynamic parameters such as bond length and bond dissociation energy. These results suggest that metallocenes might be privileged mechanophores through which highly inert coordination complexes can be made dynamic in a stimuli-responsive fashion, offering potential opportunities in dynamic metallo-supramolecular materials and in mechanochemical routes to reactive intermediates that are otherwise difficult to obtain.
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Wang S, Panyukov S, Rubinstein M, Craig SL. Quantitative Adjustment to the Molecular Energy Parameter in the Lake–Thomas Theory of Polymer Fracture Energy. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02341] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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61
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Xia Z, Alphonse VD, Trigg DB, Harrigan TP, Paulson JM, Luong QT, Lloyd EP, Barbee MH, Craig SL. 'Seeing' Strain in Soft Materials. Molecules 2019; 24:E542. [PMID: 30717294 PMCID: PMC6384768 DOI: 10.3390/molecules24030542] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 01/29/2019] [Accepted: 01/30/2019] [Indexed: 11/16/2022] Open
Abstract
Several technologies can be used for measuring strains of soft materials under high rate impact conditions. These technologies include high speed tensile test, split Hopkinson pressure bar test, digital image correlation and high speed X-ray imaging. However, none of these existing technologies can produce a continuous 3D spatial strain distribution in the test specimen. Here we report a novel passive strain sensor based on poly(dimethyl siloxane) (PDMS) elastomer with covalently incorporated spiropyran (SP) mechanophore to measure impact induced strains. We have shown that the incorporation of SP into PDMS at 0.25 wt% level can adequately measure impact strains via color change under a high strain rate of 1500 s-1 within a fraction of a millisecond. Further, the color change is fully reversible and thus can be used repeatedly. This technology has a high potential to be used for quantifying brain strain for traumatic brain injury applications.
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Lin Y, Chang CC, Craig SL. Mechanical generation of isocyanate by mechanically induced retro [2 + 2] cycloaddition of a 1,2-diazetidinone mechanophore. Org Chem Front 2019. [DOI: 10.1039/c9qo00262f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mechanical activation of a 1,2-diazetidinone mechanophore via ultrasonic sonication leads to the formation of isocyanate and imine products.
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63
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Wang Z, Craig SL. Stereochemical effects on the mechanochemical scission of furan–maleimide Diels–Alder adducts. Chem Commun (Camb) 2019; 55:12263-12266. [DOI: 10.1039/c9cc06361g] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
An internal competition between mechanochemical reactions unveils the relative mechanical reactivity of furan–maleimide Diels–Alder (DA) stereoisomers.
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Rohde RC, Basu A, Okello LB, Barbee MH, Zhang Y, Velev OD, Nelson A, Craig SL. Mechanochromic composite elastomers for additive manufacturing and low strain mechanophore activation. Polym Chem 2019. [DOI: 10.1039/c9py01053j] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Composite silicone inks provide access to 3D-printable elastomers that are mechanochemically active at lower strains that single component analogs.
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65
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Bowser BH, Craig SL. Correction: Empowering mechanochemistry with multi-mechanophore polymer architectures. Polym Chem 2019. [DOI: 10.1039/c9py90180a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Correction for ‘Empowering mechanochemistry with multi-mechanophore polymer architectures’ by Brandon H. Bowser et al., Polym. Chem., 2018, 9, 3583–3593.
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Sha Y, Zhang Y, Zhu T, Tan S, Cha Y, Craig SL, Tang C. Ring-Closing Metathesis and Ring-Opening Metathesis Polymerization toward Main-Chain Ferrocene-Containing Polymers. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b02064] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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67
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Lin Y, Barbee MH, Chang CC, Craig SL. Regiochemical Effects on Mechanophore Activation in Bulk Materials. J Am Chem Soc 2018; 140:15969-15975. [DOI: 10.1021/jacs.8b10376] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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68
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Sha Y, Zhang Y, Xu E, Wang Z, Zhu T, Craig SL, Tang C. Quantitative and Mechanistic Mechanochemistry in Ferrocene Dissociation. ACS Macro Lett 2018; 7:1174-1179. [PMID: 31098336 DOI: 10.1021/acsmacrolett.8b00625] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ferrocene is classically regarded as being highly inert owing to the large dissociation energy of metal-cyclopentadienyl (Cp) bonds. We show that the Fe-Cp bond in ferrocene is the preferential site of mechanochemical scission in the pulsed ultrasonication of main-chain ferrocene-containing polybutadiene-derived polymers. Quantitative studies reveal that the Fe-Cp bond is similar in strength to the carbon-nitrogen bond of an azobisdialkylnitrile (bond dissociation energy < -0 kcal/mol), despite the significantly higher Fe-Cp bond dissociation energy (approximately 90 kcal/mol). Mechanistic studies are consistent with a predominately heterolytic mechanism of chain scission. DFT calculations provide insights into the origins of ferrocene's mechanical lability.
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69
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Barbee MH, Kouznetsova T, Barrett SL, Gossweiler GR, Lin Y, Rastogi SK, Brittain WJ, Craig SL. Substituent Effects and Mechanism in a Mechanochemical Reaction. J Am Chem Soc 2018; 140:12746-12750. [PMID: 30260221 DOI: 10.1021/jacs.8b09263] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the effect of substituents on the force-induced reactivity of a spiropyran mechanophore. Using single molecule force spectroscopy, force-rate behavior was determined for a series of spiropyran derivatives substituted with H, Br, or NO2 para to the breaking spirocyclic C-O bond. The force required to achieve the rate constants of ∼10 s-1 necessary to observe transitions in the force spectroscopy experiments depends on the substituent, with the more electron withdrawing substituent requiring less force. Rate constants at 375 pN were determined for all three derivatives, and the force-coupled rate dependence on substituent identity is well explained by a Hammett linear free energy relationship with a value of ρ = 2.9, consistent with a highly polar transition state with heterolytic, dissociative character. The methodology paves the way for further application of linear free energy relationships and physical organic methodologies to mechanochemical reactions, and the characterization of new force probes should enable additional, quantitative studies of force-coupled molecular behavior in polymeric materials.
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70
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Barbee MH, Mondal K, Deng JZ, Bharambe V, Neumann TV, Adams JJ, Boechler N, Dickey MD, Craig SL. Mechanochromic Stretchable Electronics. ACS APPLIED MATERIALS & INTERFACES 2018; 10:29918-29924. [PMID: 30091895 DOI: 10.1021/acsami.8b09130] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Soft and stretchable electronics are promising for a variety of applications such as wearable electronics, human-machine interfaces, and soft robotics. These devices, which are often encased in elastomeric materials, maintain or adjust their functionality during deformation, but can fail catastrophically if extended too far. Here, we report new functional composites in which stretchable electronic properties are coupled to molecular mechanochromic function, enabling at-a-glance visual cues that inform user control. These properties are realized by covalently incorporating a spiropyran mechanophore within poly(dimethylsiloxane) to indicate with a visible color change that a strain threshold has been reached. The resulting colorimetric elastomers can be molded and patterned so that, for example, the word "STOP" appears when a critical strain is reached, indicating to the user that further strain risks device failure. We also show that the strain at color onset can be controlled by layering silicones with different moduli into a composite. As a demonstration, we show how color onset can be tailored to indicate a when a specified frequency of a stretchable liquid metal antenna has been reached. The multiscale combination of mechanochromism and soft electronics offers a new avenue to empower user control of strain-dependent properties for future stretchable devices.
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71
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Bogris A, Wang J, Anyfantakis M, Loppinet B, Craig SL, Butt HJ, Fytas G. Solvent-Dependent Light-Induced Structures in Gem-Dichlorocyclopropanated Polybutadiene Solutions. J Phys Chem B 2018; 122:6995-7001. [PMID: 29890076 PMCID: PMC6122843 DOI: 10.1021/acs.jpcb.8b02463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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The
formation of permanent structures upon mild red laser illumination
in transparent polydiene solutions is examined in the case of gem-dichlorocyclopropanated
polybutadiene (gDCC-PB) polymers bearing 15% functional
units of the dichlorocyclopropane groups. The response was found to
be distinct from the precursor PB. Whereas fiber-like patterns were
clearly observed in both precursor and gDCC-PB solutions
in cyclohexane, these were absent in the case of gDCC-PB/chloroform but were present in the precursor PB/chloroform
solutions. The involved mechanical stresses were not sufficient for
the gDCC activation to be detected by NMR spectroscopy.
Remarkably, addition of even 10 wt % gDCC-PB into
the latter solution sufficed to suppress the light-induced patterning.
The importance of the chemical environment on the response to light
irradiation was further checked and confirmed by use of other PB copolymers.
Different diameter patterns and kinetics were observed. The strong
solvent and comonomer mediated effect was reflected neither in solvency
nor in optical polarizability differences of the polymers solvent
couples.
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72
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Fritze UF, Craig SL, von Delius M. Disulfide-centered poly(methyl acrylates): Four different stimuli to cleave a polymer. ACTA ACUST UNITED AC 2018. [DOI: 10.1002/pola.29021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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73
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Bowser BH, Craig SL. Empowering mechanochemistry with multi-mechanophore polymer architectures. Polym Chem 2018. [DOI: 10.1039/c8py00720a] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Multi-mechanophore polymers provide advantages in characterization and function relative to chain-centered, single mechanophore polymers.
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Cho S, Kang S, Pandya A, Shanker R, Khan Z, Lee Y, Park J, Craig SL, Ko H. Large-Area Cross-Aligned Silver Nanowire Electrodes for Flexible, Transparent, and Force-Sensitive Mechanochromic Touch Screens. ACS NANO 2017; 11:4346-4357. [PMID: 28397485 DOI: 10.1021/acsnano.7b01714] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Silver nanowire (AgNW) networks are considered to be promising structures for use as flexible transparent electrodes for various optoelectronic devices. One important application of AgNW transparent electrodes is the flexible touch screens. However, the performances of flexible touch screens are still limited by the large surface roughness and low electrical to optical conductivity ratio of random network AgNW electrodes. In addition, although the perception of writing force on the touch screen enables a variety of different functions, the current technology still relies on the complicated capacitive force touch sensors. This paper demonstrates a simple and high-throughput bar-coating assembly technique for the fabrication of large-area (>20 × 20 cm2), highly cross-aligned AgNW networks for transparent electrodes with the sheet resistance of 21.0 Ω sq-1 at 95.0% of optical transmittance, which compares favorably with that of random AgNW networks (sheet resistance of 21.0 Ω sq-1 at 90.4% of optical transmittance). As a proof of concept demonstration, we fabricate flexible, transparent, and force-sensitive touch screens using cross-aligned AgNW electrodes integrated with mechanochromic spiropyran-polydimethylsiloxane composite film. Our force-sensitive touch screens enable the precise monitoring of dynamic writings, tracing and drawing of underneath pictures, and perception of handwriting patterns with locally different writing forces. The suggested technique provides a robust and powerful platform for the controllable assembly of nanowires beyond the scale of conventional fabrication techniques, which can find diverse applications in multifunctional flexible electronic and optoelectronic devices.
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75
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Wang J, Kouznetsova TB, Boulatov R, Craig SL. Mechanical gating of a mechanochemical reaction cascade. Nat Commun 2016; 7:13433. [PMID: 27848956 PMCID: PMC5116086 DOI: 10.1038/ncomms13433] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/04/2016] [Indexed: 01/22/2023] Open
Abstract
Covalent polymer mechanochemistry offers promising opportunities for the control and engineering of reactivity. To date, covalent mechanochemistry has largely been limited to individual reactions, but it also presents potential for intricate reaction systems and feedback loops. Here we report a molecular architecture, in which a cyclobutane mechanophore functions as a gate to regulate the activation of a second mechanophore, dichlorocyclopropane, resulting in a mechanochemical cascade reaction. Single-molecule force spectroscopy, pulsed ultrasonication experiments and DFT-level calculations support gating and indicate that extra force of >0.5 nN needs to be applied to a polymer of gated gDCC than of free gDCC for the mechanochemical isomerization gDCC to proceed at equal rate. The gating concept provides a mechanism by which to regulate stress-responsive behaviours, such as load-strengthening and mechanochromism, in future materials designs.
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