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Papkov D, Delpouve N, Delbreilh L, Araujo S, Stockdale T, Mamedov S, Maleckis K, Zou Y, Andalib MN, Dargent E, Dravid VP, Holt MV, Pellerin C, Dzenis YA. Quantifying Polymer Chain Orientation in Strong and Tough Nanofibers with Low Crystallinity: Toward Next Generation Nanostructured Superfibers. ACS NANO 2019; 13:4893-4927. [PMID: 31038925 DOI: 10.1021/acsnano.8b08725] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Advanced fibers revolutionized structural materials in the second half of the 20th century. However, all high-strength fibers developed to date are brittle. Recently, pioneering simultaneous ultrahigh strength and toughness were discovered in fine (<250 nm) individual electrospun polymer nanofibers (NFs). This highly desirable combination of properties was attributed to high macromolecular chain alignment coupled with low crystallinity. Quantitative analysis of the degree of preferred chain orientation will be crucial for control of NF mechanical properties. However, quantification of supramolecular nanoarchitecture in NFs with low crystallinity in the ultrafine diameter range is highly challenging. Here, we discuss the applicability of traditional as well as emerging methods for quantification of polymer chain orientation in nanoscale one-dimensional samples. Advantages and limitations of different techniques are critically evaluated on experimental examples. It is shown that straightforward application of some of the techniques to sub-wavelength-diameter NFs can lead to severe quantitative and even qualitative artifacts. Sources of such size-related artifacts, stemming from instrumental, materials, and geometric phenomena at the nanoscale, are analyzed on the example of polarized Raman method but are relevant to other spectroscopic techniques. A proposed modified, artifact-free method is demonstrated. Outstanding issues and their proposed solutions are discussed. The results provide guidance for accurate nanofiber characterization to improve fundamental understanding and accelerate development of nanofibers and related nanostructured materials produced by electrospinning or other methods. We expect that the discussion in this review will also be useful to studies of many biological systems that exhibit nanofilamentary architectures and combinations of high strength and toughness.
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Affiliation(s)
- Dimitry Papkov
- Department of Mechanical and Materials Engineering , University of Nebraska-Lincoln , Lincoln , Nebraska 68588-0526 , United States
- Nebraska Center for Materials and Nanoscience , University of Nebraska-Lincoln , Lincoln , Nebraska 68588-0298 , United States
| | - Nicolas Delpouve
- Département Systèmes Désordonnés et Polymères, Equipe Internationale de Recherche et de Caractérisation des Amorphes et des Polymères , Normandie Univ, UNIROUEN, INSA ROUEN, CNRS, GPM , 76000 Rouen , France
| | - Laurent Delbreilh
- Département Systèmes Désordonnés et Polymères, Equipe Internationale de Recherche et de Caractérisation des Amorphes et des Polymères , Normandie Univ, UNIROUEN, INSA ROUEN, CNRS, GPM , 76000 Rouen , France
| | - Steven Araujo
- Département Systèmes Désordonnés et Polymères, Equipe Internationale de Recherche et de Caractérisation des Amorphes et des Polymères , Normandie Univ, UNIROUEN, INSA ROUEN, CNRS, GPM , 76000 Rouen , France
| | - Taylor Stockdale
- Department of Mechanical and Materials Engineering , University of Nebraska-Lincoln , Lincoln , Nebraska 68588-0526 , United States
| | - Sergey Mamedov
- Division of HORIBA Instruments, Inc. , HORIBA Scientific , 20 Knightsbridge Road , Piscataway , New Jersey 08854 , United States
| | - Kaspars Maleckis
- Department of Mechanical and Materials Engineering , University of Nebraska-Lincoln , Lincoln , Nebraska 68588-0526 , United States
| | - Yan Zou
- Department of Mechanical and Materials Engineering , University of Nebraska-Lincoln , Lincoln , Nebraska 68588-0526 , United States
| | - Mohammad Nahid Andalib
- Department of Mechanical and Materials Engineering , University of Nebraska-Lincoln , Lincoln , Nebraska 68588-0526 , United States
| | - Eric Dargent
- Département Systèmes Désordonnés et Polymères, Equipe Internationale de Recherche et de Caractérisation des Amorphes et des Polymères , Normandie Univ, UNIROUEN, INSA ROUEN, CNRS, GPM , 76000 Rouen , France
| | - Vinayak P Dravid
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Martin V Holt
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Christian Pellerin
- Département de chimie , Université de Montréal , Montréal , QC H3C 3J7 , Canada
| | - Yuris A Dzenis
- Department of Mechanical and Materials Engineering , University of Nebraska-Lincoln , Lincoln , Nebraska 68588-0526 , United States
- Nebraska Center for Materials and Nanoscience , University of Nebraska-Lincoln , Lincoln , Nebraska 68588-0298 , United States
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Kumar N, Weckhuysen BM, Wain AJ, Pollard AJ. Nanoscale chemical imaging using tip-enhanced Raman spectroscopy. Nat Protoc 2019; 14:1169-1193. [PMID: 30911174 DOI: 10.1038/s41596-019-0132-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 01/09/2019] [Indexed: 11/09/2022]
Abstract
Confocal and surface-enhanced Raman spectroscopy (SERS) are powerful techniques for molecular characterization; however, they suffer from the drawback of diffraction-limited spatial resolution. Tip-enhanced Raman spectroscopy (TERS) overcomes this limitation and provides chemical information at length scales in the tens of nanometers. In contrast to alternative approaches to nanoscale chemical analysis, TERS is label free, is non-destructive, and can be performed in both air and liquid environments, allowing its use in a diverse range of applications. Atomic force microscopy (AFM)-based TERS is especially versatile, as it can be applied to a broad range of samples on various substrates. Despite its advantages, widespread uptake of this technique for nanoscale chemical imaging has been inhibited by various experimental challenges, such as limited lifetime, and the low stability and yield of TERS probes. This protocol details procedures that will enable researchers to reliably perform TERS imaging using a transmission-mode AFM-TERS configuration on both biological and non-biological samples. The procedure consists of four stages: (i) preparation of plasmonically active TERS probes; (ii) alignment of the TERS system; (iii) experimental procedures for nanoscale imaging using TERS; and (iv) TERS data processing. We provide procedures and example data for a range of different sample types, including polymer thin films, self-assembled monolayers (SAMs) of organic molecules, photocatalyst surfaces, small molecules within biological cells, single-layer graphene and single-walled carbon nanotubes in both air and water. With this protocol, TERS probes can be prepared within ~23 h, and each subsequent TERS experimental procedure requires 3-5 h.
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Affiliation(s)
- Naresh Kumar
- National Physical Laboratory, Teddington, UK.,Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, the Netherlands
| | - Bert M Weckhuysen
- Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, the Netherlands
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