1
|
Todros S, Natali AN, Piga M, Giffin GA, Pace G, Di Noto V. Interplay between chemical structure and ageing on mechanical and electric relaxations in poly(ether-block-amide)s. Polym Degrad Stab 2013. [DOI: 10.1016/j.polymdegradstab.2013.03.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
2
|
Quarti C, Milani A, Civalleri B, Orlando R, Castiglioni C. Ab initio calculation of the crystalline structure and IR spectrum of polymers: nylon 6 polymorphs. J Phys Chem B 2012; 116:8299-311. [PMID: 22697809 DOI: 10.1021/jp303715v] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
State-of-the-art computational methods in solid-state chemistry were applied to predict the structural and spectroscopic properties of the α and γ crystalline polymorphs of nylon 6. Density functional theory calculations augmented with an empirical dispersion correction (DFT-D) were used for the optimization of the two different crystal structures and of the isolated chains, characterized by a different regular conformation and described as one-dimensional infinite chains. The structural parameters of both crystalline polymorphs were correctly predicted, and new insight into the interplay of conformational effects, hydrogen bonding, and van der Waals interactions in affecting the properties of the crystal structures of polyamides was obtained. The calculated infrared spectra were compared to experimental data; based on computed vibrational eigenvectors, assignment of the infrared absorptions of the two nylon 6 polymorphs was carried out and critically analyzed in light of previous investigations. On the basis of a comparison of the computed and experimental IR spectra, a set of marker bands was identified and proposed as a tool for detecting and quantifying the presence of a given polymorph in a real sample: several marker bands employed in the past were confirmed, whereas some of the previous assignments are criticized. In addition, some new marker bands are proposed. The results obtained demonstrate that accurate computational techniques are now affordable for polymers characterization, opening the way to several applications of ab initio modeling to the study of many families of polymeric materials.
Collapse
Affiliation(s)
- Claudio Quarti
- Dipartimento di Chimica, Materiali e Ingegneria Chimica G. Natta, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | | | | | | | | |
Collapse
|
3
|
Milani A, Casalegno M, Castiglioni C, Raos G. Coarse-Grained Simulations of Model Polymer Nanofibres. MACROMOL THEOR SIMUL 2011. [DOI: 10.1002/mats.201100010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
4
|
Murthy NS. Hydrogen bonding, mobility, and structural transitions in aliphatic polyamides. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.20833] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
5
|
Baldi LDC, Atvars TDZ. Avaliação da polaridade superficial de náilons por espectroscopia de fluorescência. POLIMEROS 2005. [DOI: 10.1590/s0104-14282005000100009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Este trabalho avalia a polaridade superficial de cinco tipos de náilons: -6, -11, -6,6, -6,10, -6,12 usando a escala do pireno, py. Esses náilons podem ser classificados em duas categorias: AB (nálion-6 e -11) e AABB (nálion-6,6 e 6,10 e -6,12). A escala py está baseada nas propriedades fotofísicas do pireno, que é obtida usando-se espectroscopia fotoestacionária de fluorescência e espectroscopia de decaimento de fluorescência. A partir dos espectros de fluorescência foram determinadas as razões de intensidades das bandas vibrônicas, I I/I III, que aumentam com a polaridade do náilon (náilon-6 maior que náilon-11 e assim por diante). Observou-se também que o tempo de meia vida diminui com a polaridade, como esperado. A partir destes experimentos, mostrou-se que o pireno é um sensor de polaridade de curta distância, isto é de distância similar ao seu raio molecular. Discute-se ainda a vantagem desta metodologia que agrega a facilidade na preparação de amostras, porque medidas podem ser feitas em amostras na forma de pó, pérolas ou filmes, independentemente da espessura.
Collapse
|
6
|
Alemán C, Muñoz-Guerra S. Aplicaciones de los métodos computacionales al estudio de la estructura y propiedades de polímeros. POLIMEROS 2003. [DOI: 10.1590/s0104-14282003000400010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
En este trabajo se revisan las técnicas de simulación molecular más habituales y potentes para la descripción de los polímeros a escala atómica y molecular, las cuales se han clasificado en cuánticas o clásicas dependiendo de cómo se describen las interacciones entre las partículas. Se presentan asimismo diversas aplicaciones de dichas metodologías, realizadas en nuestro laboratorio, en el contexto del estudio de la estructura y propiedades de polímeros. En particular, se muestran aplicaciones de las técnicas clásicas a la determinación de estructuras cristalinas, a estudio del plegamiento lamelar de los nylons, a la estabilidad de las estructuras supramoleculares observadas en algunos complejos tensioactivo·polielectrolito y a la difusión de gases en matrices poliméricas, mientras que el uso de técnicas cuánticas se ha ilustrado presentando estudios dedicados a la predicción de efectos cooperativos, interacciones específicas y parámetros espectroscópicos.
Collapse
|
7
|
Casas MT, Armelin E, Alemán C, Puiggalí J. On the Crystalline Structure of Even Polyoxalamides. Macromolecules 2002. [DOI: 10.1021/ma020869x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maria Teresa Casas
- Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, E−08028, Barcelona, Spain
| | - Elaine Armelin
- Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, E−08028, Barcelona, Spain
| | - Carlos Alemán
- Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, E−08028, Barcelona, Spain
| | - Jordi Puiggalí
- Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, E−08028, Barcelona, Spain
| |
Collapse
|
8
|
Affiliation(s)
- Youyong Li
- Materials and Process Simulation Center (Mail Code 139-74), Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - William A. Goddard
- Materials and Process Simulation Center (Mail Code 139-74), Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| |
Collapse
|
9
|
León S, Zanuy D, Alemán C. Influence of the presence of small gas molecules in the structure of comblike polyacrylates: a Monte Carlo study. J Comput Chem 2002; 23:685-96. [PMID: 11948586 DOI: 10.1002/jcc.10062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A theoretical strategy has been developed to study the motion of small molecules through ordered polymeric systems. The strategy, which has been incorporated into a computer program denoted MCDP/2, is especially useful to study comblike polymers organized in biphasic arrangements. This is because it is based on a configurational bias Monte Carlo algorithm, which is more efficient than conventional methods to study dense systems. The MCDP/2 program has been used to investigate the influence of CH(4) and CO(2) gas molecules in the structure of isotactic poly(octadecyl acrylate), a typical comblike polymer. For this purpose, the pure polymer and different molecular systems constituted by several gas molecules dissolved in the polymer matrix have been simulated. Results indicated that the structural relaxation of the polymer is not coupled to the motion of gas molecules. The importance of these results in the field of molecular modeling of transport properties in comblike polymers is discussed.
Collapse
Affiliation(s)
- Salvador León
- Dipartamento di Chimica "G. Ciamician," Università di Bologna, via Semi 2, Bologna I-40126, Italy
| | | | | |
Collapse
|
10
|
Armelin E, Alemán C, Puiggalí J. Structural versatility of oxalamide-based compounds: a computational study on the isomerization of the oxalamide group and the structural preferences of the polyoxalamides. J Org Chem 2001; 66:8076-85. [PMID: 11722208 DOI: 10.1021/jo010042l] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conformational properties of the oxalamide group and crystal structure of several polyoxalamides have been investigated by computational methods. First, a detailed quantum mechanical study of the conformational preferences of N,N'-dimethyloxalamide is reported. Results, which were obtained at the MP2/6-31G(d) level, provide not only the minimum energy conformations but also a description of the energetics and structural changes associated to the isomerization process of the oxalamide group. These quantum mechanical results together with those obtained from additional calculations have been used to develop a set of force-field parameters for the oxalamide group. Molecular mechanics calculations have been performed to test the parameters and to provide new information in terms of energy contributions about the isomerization of the oxalamide group. On the other hand, the new set of parameters has been used to investigate the structural preferences of polyoxalamides (-[NH-CO-CO-NH-(CH(2))(n)]-) by PCSP calculations. Results indicated that polyoxalamides with an even number of methylene groups adopt a structure with one hydrogen bonding direction, whereas polymers with an odd number of methylene groups prefer a structure with two hydrogen bonding directions. The latter crystal structure is completely different from that observed in conventional polyamides and has been investigated in detail through Monte Carlo simulations.
Collapse
Affiliation(s)
- E Armelin
- Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain
| | | | | |
Collapse
|
11
|
Sikorski P, Atkins EDT. The Three-Dimensional Structure of Monodisperse 5-Amide Nylon 6 Crystals in the λ-Phase. Macromolecules 2001. [DOI: 10.1021/ma010305d] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pawel Sikorski
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K
| | - Edward D. T. Atkins
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K
| |
Collapse
|
12
|
Sikorski P, Jones NA, Atkins EDT, Hill MJ. Measurement of the Intersheet Shear Along the Chain Axis in Nylon 6. Macromolecules 2001. [DOI: 10.1021/ma001994g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- P. Sikorski
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K
| | - N. A. Jones
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K
| | - E. D. T. Atkins
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K
| | - M. J. Hill
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K
| |
Collapse
|
13
|
Escudero E, Subirana JA. Structure of a Cyclic Trimer as a Model of Nylon 11. Folding at Lamellar Surfaces. Macromolecules 2001. [DOI: 10.1021/ma001681l] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Encarna Escudero
- Departament Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona, Spain
| | - Juan A. Subirana
- Departament Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona, Spain
| |
Collapse
|