Polymorphism of V-amylose cocrystallized with aliphatic diols. (20th January 2021)

• Record Type: Journal Article
• Authors: Le, Cong Anh Khanh; Choisnard, Luc; Wouessidjewe, Denis; Putaux, Jean-Luc
• Is Part Of: Polymer. Volume 213(2021)
• Publication Date: 2021-01-20
• Subjects: V-amylose -- Diol -- Cocrystal -- Polymorphism; BBIOL butane-1, 3-diol -- BDIOL butane-1, 4-diol -- EDIOL ethane-1, 2-diol -- HDIOL hexane-1, 6-diol -- MPDIOL 2-methylpentane-2, 4-diol -- ED electron diffraction -- TEM transmission electron microscopy -- XRD X-ray diffraction; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2020.123302
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Chain-folded lamellar crystalline complexes of amylose with aliphatic diols were prepared and characterized by transmission electron microscopy as well as electron and X-ray diffraction. Four allomorphs were identified, depending on the complexing diol and crystallization conditions, that consisted of orthorhombic lattices of antiparallel 6- or 7-fold amylose single helices. Straight-chain n -diols (ethane-1, 2-diol, butane-1, 4-diol, hexane-1, 6-diol) yielded 6-fold helical complexes regardless the length of the linear chain, whereas a bulkier branched diol (2-methylpentane-2, 4-diol) induced the formation of 7-fold helices. Butane-1, 3-diol, that contains a straight carbon chain with one end and one side hydroxyl group, induced both 6- and 7-fold helical conformations depending on the crystallization conditions. When a diol induced more than one allomorph, an adequate control of its concentration and crystallization temperature allowed targeting a specific crystalline form. Upon drying, all allomorphs were converted into more compact pseudo-hexagonal structures. The dried form of a given complex generally retained the same helical conformation as the hydrated one. Graphical abstract: Image 1 Highlights: Amylose formed chain-folded lamellar cocrystals with aliphatic diols. Four allomorphs based on 6- or 7-fold amylose helices were characterized. The resulting allomorph depended on the topology of the complexing diol. A diol could yield different allomorphs depending on the crystallization conditions. Different drying pathways with new intermediate structures were identified.