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Enantiotropy of Simvastatin as a Result of Weakened Interactions in the Crystal Lattice: Entropy-Driven Double Transitions and the Transient Modulated Phase as Seen by Solid-State NMR Spectroscopy. Molecules 2022; 27:molecules27030679. [PMID: 35163943 PMCID: PMC8838109 DOI: 10.3390/molecules27030679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/01/2022] Open
Abstract
In crystalline molecular solids, in the absence of strong intermolecular interactions, entropy-driven processes play a key role in the formation of dynamically modulated transient phases. Specifically, in crystalline simvastatin, the observed fully reversible enantiotropic behavior is associated with multiple order–disorder transitions: upon cooling, the dynamically disordered high-temperature polymorphic Form I is transformed to the completely ordered low-temperature polymorphic Form III via the intermediate (transient) modulated phase II. This behavior is associated with a significant reduction in the kinetic energy of the rotating and flipping ester substituents, as well as a decrease in structural ordering into two distinct positions. In transient phase II, the conventional three-dimensional structure is modulated by periodic distortions caused by cooperative conformation exchange of the ester substituent between the two states, which is enabled by weakened hydrogen bonding. Based on solid-state NMR data analysis, the mechanism of the enantiotropic phase transition and the presence of the transient modulated phase are documented.
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Kelnar I, Zhigunov A, Kaprálková L, Fortelný I, Krejčíková S, Dybal J, Janata M, Brus J, Kobera L, Štengl V. Ductile/brittle PA6/PS system: Effect of carbon nanoplatelets‐modified interface on performance. J Appl Polym Sci 2020. [DOI: 10.1002/app.49100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ivan Kelnar
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Alexander Zhigunov
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Ludmila Kaprálková
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Ivan Fortelný
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Sabina Krejčíková
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Jiří Dybal
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Miroslav Janata
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Jiří Brus
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Libor Kobera
- Institute of Macromolecular ChemistryCzech Academy of Sciences Praha Czech Republic
| | - Václav Štengl
- Materials Chemistry DepartmentInstitute of Inorganic Chemistry of the Czech Academy of Sciences Řež Czech Republic
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Zhang R, Nishiyama Y, Ramamoorthy A. Exploiting heterogeneous time scale of dynamics to enhance 2D HETCOR solid-state NMR sensitivity. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 309:106615. [PMID: 31669793 DOI: 10.1016/j.jmr.2019.106615] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/11/2019] [Accepted: 10/03/2019] [Indexed: 06/10/2023]
Abstract
Multidimensional solid-state NMR spectroscopy plays a significant role in offering atomic-level insights into molecular systems. In particular, heteronuclear chemical shift correlation (HETCOR) experiments could provide local chemical and structural information in terms of spatial heteronuclear proximity and through-bond connectivity. In solid state, the transfer of magnetization between heteronuclei, a key step in HETCOR experiments, is usually achieved using cross-polarization (CP) or insensitive nuclei enhanced by polarization transfer (INEPT) depending on the sample characteristics and magic-angle-spinning (MAS) frequency. But, for a multiphase system constituting molecular components that differ in their time scales of mobilities, CP efficiency is pretty low for mobile components because of the averaging of heteronuclear dipolar couplings whereas INEPT is inefficient for immobile components due to the short T2 and can yield through-space connectivity due to strong proton spin diffusion for immobile components especially under moderate spinning speeds. Herein, in this study we present two 2D pulse sequences that enable the sequential acquisition of 13C/1H HETCOR NMR spectra for the rigid and mobile components by taking full advantage of the abundant proton magnetization in a single experiment with barely increasing the overall experimental time. In particular, the 13C-detected HETCOR experiment could be applied under slow MAS conditions, where a multiple-pulse sequence is typically employed to enhance 1H spectral resolution in the indirect dimension. In contrast, the 1H-detected HETCOR experiment should be applied under ultrafast MAS, where CP and heteronuclear nuclear Overhauser effect (NOE) polarization transfer are combined to enhance 13C signal intensities for mobile components. These pulse sequences are experimentally demonstrated on two model systems to obtain 2D 13C/1H chemical shift correlation spectra of rigid and mobile components independently and separately. These pulse sequences can be used for dynamics based spectral editing and resonance assignments. Therefore, we believe the proposed 2D HETCOR NMR pulse sequences will be beneficial for the structural studies of heterogeneous systems containing molecular components that differ in their time scale of motions for understanding the interplay of structures and properties.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, Biomedical Engineering, Maromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Yusuke Nishiyama
- NMR Science and Development Division, RIKEN SPring-8 Center, Nanocrystallography Unit, RIKEN-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan; JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan.
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, Biomedical Engineering, Maromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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Abstract
Two polymorphs of the drug compound metergoline (C25H29N3O2) were investigated in detail by solid-state NMR measurements. The results have been analysed by an advanced procedure, which uses experimental input together with the results of quantum chemical calculations that were performed for molecular crystals. In this way, it was possible to assign the total of 40 1H–13C correlation pairs in a highly complex system, namely, in the dynamically disordered polymorph with two independent molecules in the unit cell of a large volume of 4234 Å3. For the simpler polymorph, which exhibits only small-amplitude motions and has just one molecule in the unit cell with a volume of 529.0 Å3, the values of the principal elements of the 13C chemical shift tensors were measured. Additionally, for this polymorph, a set of crystal structure predictions were generated, and the {13C, 1H} isotropic and 13C anisotropic chemical shielding data were computed while using the gauge-including projector augmented-wave approach combined with the “revised Perdew-Burke-Ernzerhof“ exchange-correlation functional (GIPAW-RPBE). The experimental and theoretical results were combined in an application of the newly developed strategy to polymorph discrimination. This research thus opens up new routes towards more accurate characterization of the polymorphism of drug formulations.
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Brus J, Czernek J, Hruby M, Svec P, Kobera L, Abbrent S, Urbanova M. Efficient Strategy for Determining the Atomic-Resolution Structure of Micro- and Nanocrystalline Solids within Polymeric Microbeads: Domain-Edited NMR Crystallography. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00392] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jiri Brus
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
| | - Jiri Czernek
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
| | - Martin Hruby
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
| | - Pavel Svec
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
| | - Libor Kobera
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
| | - Sabina Abbrent
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
| | - Martina Urbanova
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
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6
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A novel insight into the origin of toughness in polypropylene–calcium carbonate microcomposites: Multivariate analysis of ss-NMR spectra. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.10.071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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7
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Kharkov BB, Chizhik VI, Dvinskikh SV. Broadband cross-polarization-based heteronuclear dipolar recoupling for structural and dynamic NMR studies of rigid and soft solids. J Chem Phys 2016; 144:034201. [DOI: 10.1063/1.4939798] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Eldho KM, Rajamohanan PR, Anto R, Bulakh N, Lele AK, Ajithkumar TG. Insights into the Molecular Dynamics in Polysulfone Polymers from 13C Solid-State NMR Experiments. J Phys Chem B 2015; 119:11287-94. [DOI: 10.1021/acs.jpcb.5b03103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kavalakal Mathai Eldho
- Central NMR Facility and ‡Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Pune 411 008, India
| | - P. R. Rajamohanan
- Central NMR Facility and ‡Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Pune 411 008, India
| | - Ralf Anto
- Central NMR Facility and ‡Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Pune 411 008, India
| | - Neelima Bulakh
- Central NMR Facility and ‡Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Pune 411 008, India
| | - Ashish K. Lele
- Central NMR Facility and ‡Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Pune 411 008, India
| | - T. G. Ajithkumar
- Central NMR Facility and ‡Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Pune 411 008, India
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Policianová O, Hodan J, Brus J, Kotek J. Origin of toughness in β-polypropylene: The effect of molecular mobility in the amorphous phase. POLYMER 2015. [DOI: 10.1016/j.polymer.2015.01.047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Kelnar I, Kaprálková L, Kratochvíl J, Kotek J, Kobera L, Rotrekl J, Hromádková J. Effect of nanofiller on the behavior of a melt-drawn HDPE/PA6 microfibrillar composite. J Appl Polym Sci 2014. [DOI: 10.1002/app.41868] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Ivan Kelnar
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic; Heyrovského nám. 2 162 06 Praha Czech Republic
| | - Ludmila Kaprálková
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic; Heyrovského nám. 2 162 06 Praha Czech Republic
| | - Jaroslav Kratochvíl
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic; Heyrovského nám. 2 162 06 Praha Czech Republic
| | - Jiří Kotek
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic; Heyrovského nám. 2 162 06 Praha Czech Republic
| | - Libor Kobera
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic; Heyrovského nám. 2 162 06 Praha Czech Republic
| | - Jakub Rotrekl
- Faculty of Chemical Technology; University of Pardubice; Studentská 95, 532 10 Pardubice 2 Czech Republic
| | - Jiřina Hromádková
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic; Heyrovského nám. 2 162 06 Praha Czech Republic
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Thanh TD, Kaprálková L, Hromádková J, Kelnar I. Effect of graphite nanoplatelets on the structure and properties of PA6-elastomer nanocomposites. Eur Polym J 2014. [DOI: 10.1016/j.eurpolymj.2013.10.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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12
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Urbanova M, Kobera L, Brus J. Factor analysis of 27Al MAS NMR spectra for identifying nanocrystalline phases in amorphous geopolymers. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:734-742. [PMID: 24027195 DOI: 10.1002/mrc.4009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/20/2013] [Accepted: 08/20/2013] [Indexed: 06/02/2023]
Abstract
Nanostructured materials offer enhanced physicochemical properties because of the large interfacial area. Typically, geopolymers with specifically synthesized nanosized zeolites are a promising material for the sorption of pollutants. The structural characterization of these aluminosilicates, however, continues to be a challenge. To circumvent complications resulting from the amorphous character of the aluminosilicate matrix and from the low concentrations of nanosized crystallites, we have proposed a procedure based on factor analysis of (27)Al MAS NMR spectra. The capability of the proposed method was tested on geopolymers that exhibited various tendencies to crystallize (i) completely amorphous systems, (ii) X-ray amorphous systems with nanocrystalline phases, and (iii) highly crystalline systems. Although the recorded (27)Al MAS NMR spectra did not show visible differences between the amorphous systems (i) and the geopolymers with the nanocrystalline phase (ii), the applied factor analysis unambiguously distinguished these materials. The samples were separated into the well-defined clusters, and the systems with the evolving crystalline phase were identified even before any crystalline fraction was detected by X-ray powder diffraction. Reliability of the proposed procedure was verified by comparing it with (29)Si MAS NMR spectra. Factor analysis of (27)Al MAS NMR spectra thus has the ability to reveal spectroscopic features corresponding to the nanocrystalline phases. Because the measurement time of (27)Al MAS NMR spectra is significantly shorter than that of (29)Si MAS NMR data, the proposed procedure is particularly suitable for the analysis of large sets of specifically synthesized geopolymers in which the formation of the limited fractions of nanocrystalline phases is desired.
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Affiliation(s)
- Martina Urbanova
- Institute of Macromolecular Chemistry AS CR, v.v.i., Heyrovsky sq. 2, 162 06, Prague 6, Czech Republic
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Borsacchi S, Sudhakaran U, Geppi M, Ricci L, Liuzzo V, Ruggeri G. Synthesis, characterization, and solid-state NMR investigation of organically modified bentonites and their composites with LDPE. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:9164-9172. [PMID: 23786424 DOI: 10.1021/la401686p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Polymer/clay nanocomposites show remarkably improved properties (mechanical properties, as well as decreased gas permeability and flammability, etc.) with respect to their microscale counterparts and pristine polymers. Due to the substantially apolar character of most of the organic polymers, natural occurring hydrophilic clays are modified into organophilic clays with consequent increase of the polymer/clay compatibility. Different strategies have been developed for the preparation of nanocomposites with improved properties, especially aimed at achieving the best dispersion of clay platelets in the polymer matrix. In this paper we present the preparation and characterization of polymer/clay nanocomposites composed of low-density polyethylene (LDPE) and natural clay, montmorillonite-containing bentonite. Two different forms of the clay have been considered: the first, a commercial organophilic bentonite (Nanofil 15), obtained by exchanging the natural cations with dimethyldioctadecylammonium (2C18) cations, and the second, obtained by performing a grafting reaction of an alkoxysilane containing a polymerizable group, 3-(trimethoxysilyl)propyl methacrylate (TSPM), onto Nanofil 15. Both the clays and LDPE/clay nanocomposites were characterized by thermal, FT-IR, and X-ray diffraction techniques. The samples were also investigated by means of (29)Si, (13)C, and (1)H solid-state NMR, obtaining information on the structural properties of the modified clays. Moreover, by exploiting the effect of bentonite paramagnetic (Fe(3+)) ions on proton spin-lattice relaxation times (T1's), useful information about the extent of the polymer-clay dispersion and their interfacial interactions could be obtained.
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Affiliation(s)
- Silvia Borsacchi
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy.
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15
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Zhang R, Chen Y, Chen T, Sun P, Li B, Ding D. Accessing Structure and Dynamics of Mobile Phase in Organic Solids by Real-Time T1C Filter PISEMA NMR Spectroscopy. J Phys Chem A 2012; 116:979-84. [DOI: 10.1021/jp2078902] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rongchun Zhang
- School of Physics, Nankai University, Tianjin 300071, People's Republic of China
| | - Yuzhu Chen
- Key Laboratory of Functional Polymer Materials, Ministry of Education, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Tiehong Chen
- Key Laboratory of Functional Polymer Materials, Ministry of Education, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Pingchuan Sun
- Key Laboratory of Functional Polymer Materials, Ministry of Education, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Baohui Li
- School of Physics, Nankai University, Tianjin 300071, People's Republic of China
| | - Datong Ding
- School of Physics, Nankai University, Tianjin 300071, People's Republic of China
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Han K, Zhang X, Zhan S, Yu M. Simultaneously Enhancing Mechanical Properties and Melt Flow Ability of Polyamide 6 by Blending with a Hyperbranched Polymer. J MACROMOL SCI B 2010. [DOI: 10.1080/00222341003641529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Keqing Han
- a State Key Laboratory of Modification for Chemical Fibers and Polymer Materials, College of Materials Science and Engineering , Donghua University , Shanghai, PR China
| | - Xiong Zhang
- a State Key Laboratory of Modification for Chemical Fibers and Polymer Materials, College of Materials Science and Engineering , Donghua University , Shanghai, PR China
| | - Shan Zhan
- a State Key Laboratory of Modification for Chemical Fibers and Polymer Materials, College of Materials Science and Engineering , Donghua University , Shanghai, PR China
| | - Muhuo Yu
- a State Key Laboratory of Modification for Chemical Fibers and Polymer Materials, College of Materials Science and Engineering , Donghua University , Shanghai, PR China
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17
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Wang K, Chen Y. Microstructures and Mechanical Properties of Poly(Trimethylene Terephthalate)/Maleic Anhydride Grafted Poly(Ethylene-octene)/Polypropylene Blends. J MACROMOL SCI B 2010. [DOI: 10.1080/00222341003648763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Kunyan Wang
- a School of Life Science , Huzhou Teachers College , Huzhou, P. R. China
| | - Yanmo Chen
- b State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering , Donghua University , Shanghai, P. R. China
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Wang K, Chen Y. Effect of Organoclay Platelets on Crystallization of PTT/EPDM-g-MA Blends: Isothermal Crystallization. J MACROMOL SCI B 2009. [DOI: 10.1080/00222340903028985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Kunyan Wang
- a State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering , Donghua University , Shanghai, Peoples Republic of China
| | - Yanmo Chen
- a State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering , Donghua University , Shanghai, Peoples Republic of China
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Wang K, Chen Y, Zhang Y. Effect of Organoclay Platelets on Crystallization of PTT/EPDM-g-MA Blends: Nonisothermal Melt Crystallization Kinetics. J MACROMOL SCI B 2009. [DOI: 10.1080/00222340802680027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Kunyan Wang
- a State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering , Donghua University , Shanghai, P. R. China
| | - Yanmo Chen
- a State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering , Donghua University , Shanghai, P. R. China
| | - Yu Zhang
- a State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering , Donghua University , Shanghai, P. R. China
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Kotek J, Kelnar I, Baldrian J, Šlouf M. Deformation and fracture behavior of polyamide nanocomposites: The effect of clay dispersion. J Appl Polym Sci 2008. [DOI: 10.1002/app.28859] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Kelnar I, Rotrekl J, Kotek J, Kaprálková L. Effect of montmorillonite modification on the behaviour of polyamide/polystyrene blends. POLYM INT 2008. [DOI: 10.1002/pi.2475] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Goitisolo I, Eguiazábal J, Nazabal J. Structure and properties of an hybrid system based on bisphenol A polycarbonate modified by A polyamide 6/organoclay nanocomposite. Eur Polym J 2008. [DOI: 10.1016/j.eurpolymj.2008.04.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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23
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Brus J, Urbanová M, Strachota A. Epoxy Networks Reinforced with Polyhedral Oligomeric Silsesquioxanes: Structure and Segmental Dynamics as Studied by Solid-State NMR. Macromolecules 2007. [DOI: 10.1021/ma702140g] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jiri Brus
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
| | - Martina Urbanová
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
| | - Adam Strachota
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 162 06 Prague 6, Czech Republic
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Dasari A, Lim SH, Yu ZZ, Mai YW. Toughening, Thermal Stability, Flame Retardancy, and Scratch–Wear Resistance of Polymer–Clay Nanocomposites. Aust J Chem 2007. [DOI: 10.1071/ch06418] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Addition of a small percent of clay to polymers improves their stiffness, strength, dimensional stability, and thermal, optical, and barrier properties. Improvements are often attributed to the availability of large numbers of clay nanolayers with tremendous interfacial area. Despite the positive effects from the addition of clay, there are unresolved issues, such as embrittlement, thermal stability, flame retardancy, scratch–wear response of the resultant nanocomposites, and/or achieving a balance between different mechanical and physical properties. In this review, we discuss these issues and the approaches that have been adopted in the expectation of resolving and understanding them, with particular emphasis on our recent and current research.
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