Morphology and Enzymatic Degradation of Solution-Grown Single Crystals of Poly(ethylene succinate)

Abstract

Solution-grown lamellar single crystals of poly(ethylene succinate) (PES) were prepared from a 0.025% solution of monochlorobenzene under an isothermal crystallization condition. Lozengeshaped lamellar crystals with and without spiral growth were obtained at different crystallization temperature. The crystals produced well-resolved electron diffractograms. Polyethylene decoration of the crystals resulted in a "cross-sector" surface morphology and showed that the average direction of chainfolding is parallel to the crystal growth planes. In some cases, the lamellar crystals showed spiral growths originating from screw dislocations with both left-handed and right-handed forms. Two extracellular poly-(hydroxybutyrate) (PHB) depolymerases purified from Alcaligenes faecalis T1 and Pseudomonas stutzeri YM1006 were used for the enzymatic degradation of the PES lamellar crystals. Adsorption of both the extracellular PHB depolymerases onto the crystal surface was observed using immuno-gold labeling technique. The enzyme molecules were homogeneously distributed on the surface of PES lamellar crystals. When the extracellular PHB depolymerase from A. faecalis T1 was applied to a suspension of PES crystals, the turbidity of crystal suspension did not decrease. This indicated that the A. faecalis T1 depolymerase could not degrade the PES crystals even though it can adsorb onto the crystal surface. On the other hand, enzymatic hydrolysis by the extracellular PHB depolymerase from P. stutzeri YM1006 was confirmed by the decrease in turbidity. The degradation progressed from the edges of the lamellar crystals without decreasing the molecular weights and the lamellar thicknesses. The difference in enzymatic activity seems to be due to the recognition of the distance between ester bonds in molecular chain by the active site of the enzyme molecule.

Molecular packing and crystalline morphologies of biodegradable poly(alkylene dicarboxylate)s derived from 1,6-hexanediol

“…These features support a micro-crystal structure that explains the striations observed in the studied polyesters. Studies of the morphological changes of lamellar crystals during enzymatic degradation have also been performed for different polyesters like poly(3-hydroxybutirate) [27,28], poly(3-caprolactone) [24] and poly(ethylene succinate) [29].…”

Tannin Induced Single Crystalline Morphology in Poly(ethylene succinate)

“…[1] Solvent-growth single crystals in PESu reportedly exhibit a diamond shape with thickness ¼ 7-8 nm. [2] Upon crystallization at 80 8C, the single crystals can assume either a left-handed screw or right-handed screw morphology, to which the authors attributed to the six types of (chain conformations) in PESu leading to helical handedness effects. [3,4] Some polymer blends are miscible with strong interactions like H-bonding forces, such as poly(ethylene oxide) (PEO)/styrene-hydroxystyrene copolymer (SHS), [5] PEO/poly( p-vinyl phenol) (PVPh), [6] PEO/4,4 0 -diaminodiphenylsulfone (DDS), [6,7] PEO/ unsaturated polyester resin (PER) [8] and PEO/hydroquinine, [9] etc.…”

Preferential Incorporation of Azelaic Acid Units into the Crystalline Phase of the Copoly(Alkylene Dicarboxylate) Derived from 1,9-Nonanediol and an Equimolar Mixture of Pimelic and Azelaic Acids

“…Single lamellar crystals obtained by crystallization from dilute solutions are ideal systems to detect how hydrolytic and/or enzymatic degradation of these crystalline phases takes place. Therefore, extensive studies have been performed with single crystals of different polyesters [30,31] including poly(ethylene succinate) [32], poly(butylene adipate) [33] and poly(octamethylene suberate) [34]. In some cases, enzymatic attack was observed to occur preferentially on determined crystal sectors, suggesting that both molecular packing and the nature of molecular folds play a crucial role in the enzymatic degradation process [34].…”