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Unusual crystals of...
Unusual crystals of poly(epsilon-caprolactone) by unusual crystallisation : The effects of rapid cooling and fast solvent loss on the morphology, crystal structure and melting
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- Sanandaji, Nima (author)
- KTH,Polymera material
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- Ovaskainen, Louise (author)
- KTH,Fiberteknologi
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Gunnewiek, M. Klein (author)
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Vancso, G. J. (author)
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- Hedenqvist, Mikael S. (author)
- KTH,Polymera material
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Yu, S. (author)
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- Eriksson, Lars (author)
- Stockholms universitet,Institutionen för material- och miljökemi (MMK)
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Roth, S. V. (author)
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- Gedde, Ulf W. (author)
- KTH,Polymera material
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Vansco, M. S. (author)
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Yu, L. (author)
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(creator_code:org_t)
- Elsevier BV, 2013
- 2013
- English.
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In: Polymer. - : Elsevier BV. - 0032-3861 .- 1873-2291. ; 54:5, s. 1497-1503
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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https://urn.kb.se/re...
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Abstract
Subject headings
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- The lateral habit, unit cell structure and melting behaviour of single crystals of poly(epsilon-caprolactone) (PCL) prepared by the rapid expansion of a supercritical solution technique was studied by AFM at ambient and higher temperatures and by grazing-incident X-ray scattering using a synchrotron source. After dissolving PCL in a solution of supercritical CO2 and 0.1 vol.% chloroform, an extremely fast phase transfer from a supercritical to a gas-like state occurred during expansion into atmospheric conditions, leading to a temporary temperature drop to below -;50 degrees C at the silica surface where the crystals were deposited. Single crystals of a hitherto unreported rectangular lateral habit were observed. Six-sided crystals were also observed, but they were fewer than the rectangular crystals and in addition the angles between the lateral faces were different from the theoretical angles between adjacent {110} faces and {110} and {100} faces. X-ray scattering indicated a polymorphic structure also including the orthorhombic (110) and (200) diffraction peaks. Distinct low angle peaks essentially along the c-axis indicated a stacking on a very fine scale (3.7-4.7 nm) within the crystals. The equatorial diffraction peaks indicated a less dense packing of the PCL stems. Rectangular single crystals with a height according to AFM of 11-27 nm melted between 40 and 45 degrees C, which is lower than the melting points (55 degrees C) recorded for the distorted six-sided crystals. The unusual conditions for crystallisation used gave the polymer molecules a severe limitation to rearrange from the initial random coil state. The facetted crystals consisted of a stack of 4 nm thick blocks; these blocks most probably constituted a regular variation in molecular packing, i.e. molecular order. The pronounced changes in the angles between adjacent faces from those observed in mature PCL crystals and the wide-angle X-ray scattering data indicated the presence of conformational disorder in the crystals.
Subject headings
- NATURVETENSKAP -- Kemi -- Polymerkemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Polymer Chemistry (hsv//eng)
Keyword
- Poly(epsilon-caprolactone)
- Polymer single crystal
- Rapid expansion of a supercritical (CO2)
- solution
Publication and Content Type
- ref (subject category)
- art (subject category)
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Polymer
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- By the author/editor
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Sanandaji, Nima
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Ovaskainen, Loui ...
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Gunnewiek, M. Kl ...
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Vancso, G. J.
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Hedenqvist, Mika ...
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Yu, S.
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show more...
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Eriksson, Lars
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Roth, S. V.
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Gedde, Ulf W.
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Vansco, M. S.
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Yu, L.
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show less...
- About the subject
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Chemical Science ...
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and Polymer Chemistr ...
- Articles in the publication
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Polymer
- By the university
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Stockholm University
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Royal Institute of Technology