Chain folding in poly(ɛ-caprolactone) studied by small-angle X-ray scattering and Raman spectroscopy. A strategy for blending in the crystalline state
1999; Royal Society of Chemistry; Volume: 9; Issue: 5 Linguagem: Inglês
10.1039/a808718k
ISSN1364-5501
AutoresSusan A. Berrill, Frank Heatley, J H Collett, David Attwood, Colin Booth, J. Patrick A. Fairclough, Anthony J. Ryan, Kyriakos Viras, Amanda J. Dutton, Ross S. Blundell,
Tópico(s)Polymer crystallization and properties
ResumoSamples of poly(ε-caprolactone), including narrow fractions obtained by preparative gel permeation chromatography (GPC), were characterised by analytical GPC and 13 C NMR spectroscopy. The crystallised samples were investigated by small-angle X-ray scattering to obtain lamellar spacings and by low-frequency Raman spectroscopy to obtain LAM-1 frequencies. Together the two methods gave a reliable estimate of the critical stem length for chain folding in poly(ε-caprolactone) crystallised at room temperature or below, i.e. 15 chain units [CL, OCO(CH 2 ) 5 ] equivalent to 105 chain atoms. A necessary requirement for molecular blending of block copolymers of ε-caprolactone and ethylene oxide with crystalline high molar mass poly(ε-caprolactone) is cocrystallisation. Hence it was concluded that a safe lower limit for successful blending is a poly(ε-caprolactone) block of 20 CL units.
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