Small- and wide-angle X-ray scattering studies on confined crystallization of Poly(ethylene glycol) in Poly(L-lactic acid) spherulite in a PLLA/PEG blend

• Published in: Polymer (Guilford) Vol. 229; p. 123971
• Main Authors: Banpean, Apisit, Takagi, Hideaki, Shimizu, Nobutaka, Igarashi, Noriyuki, Sakurai, Shinichi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 16.08.2021; Elsevier BV
• Subjects: Confined crystallization; Crystal structure; Crystallinity; Crystallization; Lamellae; Poly(ethylene glycol); Poly(L-lactic acid); Polyethylene glycol; Polylactic acid; Small angle X ray scattering; Stacking; Wide-angle X-ray scattering; X-ray scattering; Poly(L-lactic acid); Confined crystallization; Wide-angle X-ray scattering; Poly(ethylene glycol); Small-angle X-ray scattering
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2021.123971

Confined crystallization of the poly(ethylene glycol) (PEG) in poly(L-lactic acid) (PLLA) spherulite in a PLLA/PEG (50/50) blend specimen was studied by simultaneous small- and wide-angle X-ray scattering (SAXS/WAXS) measurements, where the blend specimen was subjected to the isothermal crystallization at 45.0 °C for PEG crystallization in the presence of preformed PLLA crystalline lamellae formed during the previous isothermal crystallization at 127.0 °C for 5–20 min. The WAXS results showed much suppression of the (124¯)/(1¯24) crystalline reflection peak for the blend as compared to the neat PEG, as well as much wider peak width for the same reflection. These results clearly indicate the suppression of the growth of the PEG lamellae in the thickness direction due to the space confinement by the preformed PLLA lamellae. The SAXS results also confirm the confined crystallization of PEG in the amorphous layer sandwiched by the preformed PLLA crystalline lamellae. Nevertheless, more regular stacking was formed due to the PEG crystallization as the neat PEG has the ability of forming very regular stacking of the crystalline lamellae, as evidenced by observing second-order peak in the SAXS profile for the blend specimen. [Display omitted] •We performed SAXS/WAXS to characterize PEG crystallization in PLLA/PEG blend.•WAXS profiles showed much suppression of (124‾)/(1‾24) PEG reflection.•PEG lamellar growth was suppressed due to confinement by preformed PLLA lamellae.•SAXS confirmed PEG crystallization in an amorphous layer in between PLLA lamellae.•Orientation of PEG lamellae parallel to the preformed PLLA lamellae was implied.