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Li Y, Chen R, Zhou B, Dong Y, Liu D. Rational Design of DNA Hydrogels Based on Molecular Dynamics of Polymers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2307129. [PMID: 37820719 DOI: 10.1002/adma.202307129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/03/2023] [Indexed: 10/13/2023]
Abstract
In recent years, DNA has emerged as a fascinating building material to engineer hydrogel due to its excellent programmability, which has gained considerable attention in biomedical applications. Understanding the structure-property relationship and underlying molecular determinants of DNA hydrogel is essential to precisely tailor its macroscopic properties at molecular level. In this review, the rational design principles of DNA molecular networks based on molecular dynamics of polymers on the temporal scale, which can be engineered via the backbone rigidity and crosslinking kinetics, are highlighted. By elucidating the underlying molecular mechanisms and theories, it is aimed to provide a comprehensive overview of how the tunable DNA backbone rigidity and the crosslinking kinetics lead to desirable macroscopic properties of DNA hydrogels, including mechanical properties, diffusive permeability, swelling behaviors, and dynamic features. Furthermore, it is also discussed how the tunable macroscopic properties make DNA hydrogels promising candidates for biomedical applications, such as cell culture, tissue engineering, bio-sensing, and drug delivery.
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Affiliation(s)
- Yujie Li
- Engineering Research Center of Advanced Rare Earth Materials, (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Ruofan Chen
- Engineering Research Center of Advanced Rare Earth Materials, (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Bini Zhou
- Engineering Research Center of Advanced Rare Earth Materials, (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Yuanchen Dong
- CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Dongsheng Liu
- Engineering Research Center of Advanced Rare Earth Materials, (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
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Poole III DA, Bobylev EO, Mathew S, Reek JNH. Entropy directs the self-assembly of supramolecular palladium coordination macrocycles and cages. Chem Sci 2022; 13:10141-10148. [PMID: 36128226 PMCID: PMC9430592 DOI: 10.1039/d2sc03154j] [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] [Received: 06/03/2022] [Accepted: 08/09/2022] [Indexed: 12/02/2022] Open
Abstract
The self-assembly of palladium-based cages is frequently rationalized via the cumulative enthalpy (ΔH) of bonds between coordination nodes (M, i.e., Pd) and ligand (L) components. This focus on enthalpic rationale limits the complete understanding of the Gibbs free energy (ΔG) for self-assembly, as entropic (ΔS) contributions are overlooked. Here, we present a study of the M2linL3 intermediate species (M = dinitrato(N,N,N′,N′-tetramethylethylenediamine)palladium(ii), linL = 4,4′-bipyridine), formed during the synthesis of triangle-shaped (M3linL3) and square-shaped (M4linL4) coordination macrocycles. Thermochemical analyses by variable temperature (VT) 1H-NMR revealed that the M2linL3 intermediate exhibited an unfavorable (relative) ΔS compared to M3linL3 (triangle, ΔTΔS = +5.22 kcal mol−1) or M4linL4 (square, ΔTΔS = +2.37 kcal mol−1) macrocycles. Further analysis of these constructs with molecular dynamics (MD) identified that the self-assembly process is driven by ΔG losses facilitated by increases in solvation entropy (ΔSsolv, i.e., depletion of solvent accessible surface area) that drives the self-assembly from “open” intermediates toward “closed” macrocyclic products. Expansion of our computational approach to the analysis of self-assembly in PdnbenL2n cages (benL = 4,4'-(5-ethoxy-1,3-phenylene)dipyridine), demonstrated that ΔSsolv contributions drive the self-assembly of both thermodynamic cage products (i.e., Pd12benL24) and kinetically-trapped intermediates (i.e., Pd8cL16). These studies demonstrate that ΔS drives the self-assembly of supramolecular palladium-based coordination macrocycles and cages. As this ΔS contribution arises from solvation, these findings broadly reflect the thermodynamic drive of self-assembly to form compact structures.![]()
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Affiliation(s)
- D. A. Poole III
- Homogeneous, Supramolecular, and Bioinspired Catalysis Group, van ‘t Hoff Institute for Molecular Science (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - E. O. Bobylev
- Homogeneous, Supramolecular, and Bioinspired Catalysis Group, van ‘t Hoff Institute for Molecular Science (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - S. Mathew
- Homogeneous, Supramolecular, and Bioinspired Catalysis Group, van ‘t Hoff Institute for Molecular Science (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - J. N. H. Reek
- Homogeneous, Supramolecular, and Bioinspired Catalysis Group, van ‘t Hoff Institute for Molecular Science (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
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Correa S, Grosskopf AK, Lopez Hernandez H, Chan D, Yu AC, Stapleton LM, Appel EA. Translational Applications of Hydrogels. Chem Rev 2021; 121:11385-11457. [PMID: 33938724 PMCID: PMC8461619 DOI: 10.1021/acs.chemrev.0c01177] [Citation(s) in RCA: 332] [Impact Index Per Article: 110.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Indexed: 12/17/2022]
Abstract
Advances in hydrogel technology have unlocked unique and valuable capabilities that are being applied to a diverse set of translational applications. Hydrogels perform functions relevant to a range of biomedical purposes-they can deliver drugs or cells, regenerate hard and soft tissues, adhere to wet tissues, prevent bleeding, provide contrast during imaging, protect tissues or organs during radiotherapy, and improve the biocompatibility of medical implants. These capabilities make hydrogels useful for many distinct and pressing diseases and medical conditions and even for less conventional areas such as environmental engineering. In this review, we cover the major capabilities of hydrogels, with a focus on the novel benefits of injectable hydrogels, and how they relate to translational applications in medicine and the environment. We pay close attention to how the development of contemporary hydrogels requires extensive interdisciplinary collaboration to accomplish highly specific and complex biological tasks that range from cancer immunotherapy to tissue engineering to vaccination. We complement our discussion of preclinical and clinical development of hydrogels with mechanical design considerations needed for scaling injectable hydrogel technologies for clinical application. We anticipate that readers will gain a more complete picture of the expansive possibilities for hydrogels to make practical and impactful differences across numerous fields and biomedical applications.
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Affiliation(s)
- Santiago Correa
- Materials
Science & Engineering, Stanford University, Stanford, California 94305, United States
| | - Abigail K. Grosskopf
- Chemical
Engineering, Stanford University, Stanford, California 94305, United States
| | - Hector Lopez Hernandez
- Materials
Science & Engineering, Stanford University, Stanford, California 94305, United States
| | - Doreen Chan
- Chemistry, Stanford University, Stanford, California 94305, United States
| | - Anthony C. Yu
- Materials
Science & Engineering, Stanford University, Stanford, California 94305, United States
| | | | - Eric A. Appel
- Materials
Science & Engineering, Stanford University, Stanford, California 94305, United States
- Bioengineering, Stanford University, Stanford, California 94305, United States
- Pediatric
Endocrinology, Stanford University School
of Medicine, Stanford, California 94305, United States
- ChEM-H Institute, Stanford
University, Stanford, California 94305, United States
- Woods
Institute for the Environment, Stanford
University, Stanford, California 94305, United States
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Xu X, Jerca FA, Jerca VV, Hoogenboom R. Self-Healing and Moldable Poly(2-isopropenyl-2-oxazoline) Supramolecular Hydrogels Based on a Transient Metal Coordination Network. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01242] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Xiaowen Xu
- Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281-S4, Ghent 9000, Belgium
| | - Florica Adriana Jerca
- Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281-S4, Ghent 9000, Belgium
- Centre of Organic Chemistry “Costin D. Nenitzescu” Romanian Academy, Spl. Independentei 202B, Bucharest 060023, Romania
| | - Valentin Victor Jerca
- Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281-S4, Ghent 9000, Belgium
- Centre of Organic Chemistry “Costin D. Nenitzescu” Romanian Academy, Spl. Independentei 202B, Bucharest 060023, Romania
| | - Richard Hoogenboom
- Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281-S4, Ghent 9000, Belgium
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Zhang Q, Zhu X, Li CH, Cai Y, Jia X, Bao Z. Disassociation and Reformation Under Strain in Polymer with Dynamic Metal–Ligand Coordination Cross-Linking. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02414] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Qiuhong Zhang
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P.R. China
| | - Xiangyang Zhu
- Renolit Plastic Tech (Beijing) Company Limited, Beijing 101400, P.R. China
| | - Cheng-Hui Li
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yifeng Cai
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P.R. China
| | - Xudong Jia
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P.R. China
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Zhenan Bao
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
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Affiliation(s)
- Nadeesha P. N. Wellala
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
| | - Hai T. Dong
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
| | - Jeanette A. Krause
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
| | - Hairong Guan
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
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Cai X, Xu Y, Yang R, Yang H. Preparation and investigation of temperature-responsive calix[4]arene-based molecular gels. RSC Adv 2017. [DOI: 10.1039/c7ra02076g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Higher temperature enhances the strength and the toughness of the gel comprised of kerosene and a tetracholesteryl derivative based on calix[4]arene.
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Affiliation(s)
- Xiuqin Cai
- School of Materials Science and Engineering
- Xi'an University of Technology
- Xi'an
- China
- School of Chemistry and Materials Science
| | - Yunhua Xu
- School of Materials Science and Engineering
- Xi'an University of Technology
- Xi'an
- China
| | - Rong Yang
- School of Materials Science and Engineering
- Xi'an University of Technology
- Xi'an
- China
| | - Hui Yang
- School of Chemistry and Chemical Engineering
- Shaanxi Normal University
- Xi'an 710119
- China
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Shangguan Y, Liu M, Luo G, Zheng Q. Shear induced self-thickening of chitosan/β-cyclodextrin compound solution. RSC Adv 2016. [DOI: 10.1039/c6ra24608g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Hackelbusch S, Rossow T, van Assenbergh P, Seiffert S. Chain Dynamics in Supramolecular Polymer Networks. Macromolecules 2013. [DOI: 10.1021/ma4003648] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sebastian Hackelbusch
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, D-14195
Berlin, Germany
| | - Torsten Rossow
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, D-14195
Berlin, Germany
| | - Peter van Assenbergh
- F-ISFM
Soft Matter and Functional
Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz
1, D-14109 Berlin, Germany
| | - Sebastian Seiffert
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, D-14195
Berlin, Germany
- F-ISFM
Soft Matter and Functional
Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz
1, D-14109 Berlin, Germany
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Kumpfer JR, Rowan SJ. Directed Self-Assembly of Metallosupramolecular Polymers at the Polymer-Polymer Interface. ACS Macro Lett 2012; 1:882-887. [PMID: 35607137 DOI: 10.1021/mz300224x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Directed self-assembly of a metallosupramolecular polymer is achieved at the interface between two polymer films by simple melt pressing. Blends of a 2,6-bis(N-methylbenzimidazolyl)pyridine (MeBip) side-chain functionalized polystyrene in a polystyrene matrix and Zn(NTf2)2 in a poly(methyl methacrylate) matrix were pressed together above the Tg of the matrix polymers resulting in diffusion of the components and subsequent self-assembly of the metallosupramolecular polymer at the polymer-polymer interface. The formation of the metallosupramolecular polymer was monitored by spectroscopy and microscopy and it was found that the interfacial self-assembly occurs at the processing temperatures (ca. 210 °C) within 5 min. It was further shown that this materials system resulted in robust films that exhibited a new emergent property, namely, phosphorescence, which is not exhibited by any of the individual components nor the metallosupramolecular polymer itself.
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Affiliation(s)
- Justin R. Kumpfer
- Department of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland, Ohio 44106-7202, United States
| | - Stuart J. Rowan
- Department of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland, Ohio 44106-7202, United States
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Appel EA, del Barrio J, Loh XJ, Scherman OA. Supramolecular polymeric hydrogels. Chem Soc Rev 2012; 41:6195-214. [DOI: 10.1039/c2cs35264h] [Citation(s) in RCA: 865] [Impact Index Per Article: 72.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Seiffert S, Sprakel J. Physical chemistry of supramolecular polymer networks. Chem Soc Rev 2012; 41:909-30. [DOI: 10.1039/c1cs15191f] [Citation(s) in RCA: 401] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Kumpfer JR, Wie JJ, Swanson JP, Beyer FL, Mackay ME, Rowan SJ. Influence of Metal Ion and Polymer Core on the Melt Rheology of Metallosupramolecular Films. Macromolecules 2011. [DOI: 10.1021/ma201659d] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Justin R. Kumpfer
- Department of Macromolecular Science & Engineering, Case Western Reserve University, 2100 Adelbert Rd., Cleveland, Ohio 44106-7202, United States
| | - Jeong J. Wie
- Department of Chemical Engineering, University of Delaware, 150 Academy St., Newark, Delaware 19716, United States
| | - John P. Swanson
- Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, California 93407-0402, United States
| | - Frederick L. Beyer
- U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005-5069, United States
| | - Michael E. Mackay
- Department of Chemical Engineering, University of Delaware, 150 Academy St., Newark, Delaware 19716, United States
- Department of Materials Science & Engineering, University of Delaware, 201 DuPont Hall, Newark, Delaware 19716, United States
| | - Stuart J. Rowan
- Department of Macromolecular Science & Engineering, Case Western Reserve University, 2100 Adelbert Rd., Cleveland, Ohio 44106-7202, United States
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Xu D, Craig SL. Strain Hardening and Strain Softening of Reversibly Cross-linked Supramolecular Polymer Networks. Macromolecules 2011; 44:7478-7488. [PMID: 22043083 DOI: 10.1021/ma201386t] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The large amplitude oscillatory shear behavior of metallo-supramolecular polymer networks formed by adding bis-Pd(II) cross-linkers to poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO) solution is reported. The influence of scanning frequency, dissociation rate of cross-linkers, concentration of cross-linkers, and concentration of PVP solution on the large amplitude oscillatory shear behavior is explored. In semidilute unentangled PVP solutions, above a critical scanning frequency, strain hardening of both storage moduli and loss moduli is observed. In the semidilute entangled regime of PVP solution, however, strain softening is observed for samples with faster cross-linkers (k(d) ∼ 1450 s(-1)), whereas strain hardening is observed for samples with slower cross-linkers (k(d) ∼ 17 s(-1)). The mechanism of strain hardening is attributed primarily to a strain-induced increase in the number of elastically active chains, with possible contributions from non-Gaussian stretching of polymer chains at strains approaching network fracture. The divergent strain softening of samples with faster cross-linkers in semidilute entangled PVP solutions, relative to the strain hardening of samples with slower cross-linkers, is consistent with observed shear thinning/shear thickening behavior reported previously and is attributed to the fact that the average time that a cross-linker remains detached is too short to permit the local relaxation of polymer chain segments that is necessary for a net conversion of elastically inactive to elastically active cross-linkers. These and other observations paint a picture in which strain softening and shear thinning arise from the same set of molecular mechanisms, conceptually uniting the two nonlinear responses for this system.
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Affiliation(s)
- Donghua Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
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Abstract
The linear rheological properties of networks formed by adding bis-Pd(II) cross-linkers to poly(4-vinylpyridine) (PVP) solution are examined, and the scaling law relationships between the zero shear viscosity (η(0)) of the networks versus the concentration of PVP solution (C(PVP)), the concentration of cross-linkers (C(X)), and the number density of elastically active chains (v(phantom)) are experimentally determined. The scaling law relationships are compared to the theoretical expectations of the Sticky Rouse and Sticky Reptation models (Macromolecules2001, 34, 1058-1068), and both qualitative and quantitative differences are observed.
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Affiliation(s)
- Donghua Xu
- Department of Chemistry and Center for Biologically Inspired Materials and Material Systems, Duke University, Durham, North Carolina, 27708-0346
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Xu D, Liu CY, Craig SL. Divergent Shear Thinning and Shear Thickening Behavior of Supramolecular Polymer Networks in Semidilute Entangled Polymer Solutions. Macromolecules 2011; 44:2343-2353. [PMID: 21547008 DOI: 10.1021/ma2000916] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The steady shear behavior of metallo-supramolecular polymer networks formed by bis-Pd(II) cross-linkers and semidilute entangled solutions of poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO) or N,N-dimethyl formamide (DMF) is reported. The steady shear behavior of the networks depends on the dissociation rate and association rate of the cross-linkers, the concentration of cross-linkers, and the concentration of the polymer solution. The divergent steady shear behavior-shear thinning versus shear thickening-of samples with identical structure but different cross-linker dynamics (J. Phys. Chem. Lett. 2010, 1, 1683-1686) is further explored in this paper. The divergent steady shear behavior for networks with different cross-linkers is connected to a competition between different time scales: the average time that a cross-linker remains open (τ(1)) and the local relaxation time of a segment of polymer chain (τ(segment)). When τ(1) is larger than τ(segment), shear thickening is observed. When τ(1) is smaller than τ(segment), only shear thinning is observed.
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Affiliation(s)
- Donghua Xu
- Department of Chemistry and Center for Biologically Inspired Materials and Material Systems, Duke University, Durham, North Carolina, 27708-0346
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Tennyson AG, Wiggins KM, Bielawski CW. Mechanical activation of catalysts for C-C bond forming and anionic polymerization reactions from a single macromolecular reagent. J Am Chem Soc 2010; 132:16631-6. [PMID: 21043506 DOI: 10.1021/ja107620y] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Coupling of pyridine-capped poly(methyl acrylate)s, PyP(M) (where M corresponds to the number average molecular weight in kDa), to the SCS-cyclometalated dipalladium complex [(1)(CH(3)CN)(2)] afforded organometallic polymers [(1)(PyP(M))(2)] with a concomitant doubling in molecular weight. Ultrasonication of solutions containing [(1)(PyP(M))(2)] effected the mechanical scission of a palladium-pyridine bond, where the liberated PyP(M) was trapped with excess HBF(4) as the corresponding pyridinium salt, harnessed to effect the stoichiometric deprotonation of a colorimetric indicator, or used to catalyze the anionic polymerization of α-trifluoromethyl-2,2,2-trifluoroethyl acrylate. The mechanically induced chain scission also unmasked a catalytically active palladium species which was used to facilitate carbon-carbon bond formation between benzyl cyanide and N-tosyl imines. Spectroscopic and macromolecular analyses as well as a series of control experiments demonstrated that the aforementioned structural changes were derived from mechanical forces that originated from ultrasound-induced dissociation of the polymer chains connected to the aforementioned Pd complexes.
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Affiliation(s)
- Andrew G Tennyson
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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