{"title":"Crystal Structures of Nylon–Iodine Complexes","authors":"Kohji Tashiro, Marina Gakhutishvili, Tomohiko Takahama","doi":"10.1021/acs.macromol.4c01122","DOIUrl":null,"url":null,"abstract":"The crystal structures of iodine complexes of nylon-6 and nylon-66 samples were proposed on the basis of 2-dimensional wide-angle X-ray diffraction data analysis combined with the observed polarized Raman spectral data and the density functional theoretical calculations. As reported in our previous paper (<i>Macromolecules</i>, <b>2024</b>, <i>57</i>, 2260), the skeletal chains of nylon were found to be contracted about 5% from the fully extended conformations, which are caused by the trans-to-skew torsional angle change around CH<sub>2</sub>–amide bonds so that the charge transfer occurs from the iodine ion to N–H group. The iodine ion rods are sandwiched between the nylon chains alternately. The I<sub>5</sub><sup>–</sup> and I<sub>3</sub><sup>–</sup> ion rods are oriented, respectively, along the nylon chain axis and in the direction approximately perpendicular to the chain axis. The sandwich packing structure is different among complex I and complex II, which are formed by immersing nylon-6 sample in the iodine solution of different concentration (0.5 and 3 M, respectively). The similar structure model was proposed also for nylon-66. The thus-constructed crystal structure models reproduced the observed X-ray diffraction patterns quite well. By a comparison of the X-ray diffraction data observed for the doubly oriented samples, the geometrical relation was revealed between the pristine nylon crystal and the nylon–iodine complexes.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.1000,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Macromolecules","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.macromol.4c01122","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"POLYMER SCIENCE","Score":null,"Total":0}
引用次数: 0
Abstract
The crystal structures of iodine complexes of nylon-6 and nylon-66 samples were proposed on the basis of 2-dimensional wide-angle X-ray diffraction data analysis combined with the observed polarized Raman spectral data and the density functional theoretical calculations. As reported in our previous paper (Macromolecules, 2024, 57, 2260), the skeletal chains of nylon were found to be contracted about 5% from the fully extended conformations, which are caused by the trans-to-skew torsional angle change around CH2–amide bonds so that the charge transfer occurs from the iodine ion to N–H group. The iodine ion rods are sandwiched between the nylon chains alternately. The I5– and I3– ion rods are oriented, respectively, along the nylon chain axis and in the direction approximately perpendicular to the chain axis. The sandwich packing structure is different among complex I and complex II, which are formed by immersing nylon-6 sample in the iodine solution of different concentration (0.5 and 3 M, respectively). The similar structure model was proposed also for nylon-66. The thus-constructed crystal structure models reproduced the observed X-ray diffraction patterns quite well. By a comparison of the X-ray diffraction data observed for the doubly oriented samples, the geometrical relation was revealed between the pristine nylon crystal and the nylon–iodine complexes.
期刊介绍:
Macromolecules publishes original, fundamental, and impactful research on all aspects of polymer science. Topics of interest include synthesis (e.g., controlled polymerizations, polymerization catalysis, post polymerization modification, new monomer structures and polymer architectures, and polymerization mechanisms/kinetics analysis); phase behavior, thermodynamics, dynamic, and ordering/disordering phenomena (e.g., self-assembly, gelation, crystallization, solution/melt/solid-state characteristics); structure and properties (e.g., mechanical and rheological properties, surface/interfacial characteristics, electronic and transport properties); new state of the art characterization (e.g., spectroscopy, scattering, microscopy, rheology), simulation (e.g., Monte Carlo, molecular dynamics, multi-scale/coarse-grained modeling), and theoretical methods. Renewable/sustainable polymers, polymer networks, responsive polymers, electro-, magneto- and opto-active macromolecules, inorganic polymers, charge-transporting polymers (ion-containing, semiconducting, and conducting), nanostructured polymers, and polymer composites are also of interest. Typical papers published in Macromolecules showcase important and innovative concepts, experimental methods/observations, and theoretical/computational approaches that demonstrate a fundamental advance in the understanding of polymers.