Visualization of the Recrystallization of Solution-Grown Poly[(R)-3-hydroxybutyrate] Lamellar Crystals

Lee, Won‐Ki; Iwata, T.; Su, Fengyu; Furuhashi, Yukiko; Doi, Yoshiharu

doi:10.1002/1521-3927(20010501)22:8<629::aid-marc629>3.0.co;2-k

Cited by 8 publications

(8 citation statements)

References 6 publications

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“…Solution‐grown single crystals of PCL prepared under isothermal crystallization conditions were the same typical chain‐folded lamellar crystals as those of other biodegradable aliphatic polyesters, poly[( R )‐3‐hydroxybutyrate] (P(3HB)),8–12 poly( L ‐lactic acid) (PLLA),15 poly(β‐propiolactone) (PPL),13 poly(ethylene succinate) (PES)14 etc reported in our previous works. Lath‐shaped single crystals of P(3HB) and PPL were degraded by some kinds of extracellular PHB depolymerases from crystal ends and edges provoking the splintering of crystals and yielding the crystal fragments without decrease of molecular weight and lamellar thickness 9.…”

Section: Resultssupporting

confidence: 65%

“…Until now, we have studied the enzymatic degradation mechanism of the crystal regions of biodegradable aliphatic polyesters, such as poly[( R )‐3‐hydroxybutyrate],8–12 poly(β‐propiolactone)13 and poly(ethylene succinate)14 with three kinds of extracellular PHB depolymerases, and poly( L ‐lactic acid) with proteinase‐K,15 by using their solution‐grown single crystals. Single crystals are considered as a useful model substrate to elucidate the mechanism of crystal growth and enzymatic degradation of the crystal region.…”

Section: Introductionmentioning

confidence: 99%

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Morphology and enzymatic degradation of poly(ϵ‐caprolactone) single crystals: does a polymer single crystal consist of micro‐crystals?

Iwata

Doi

2002

Polymer International

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Solution‐grown lamellar single crystals of poly(ϵ‐caprolactone) (PCL) were prepared from a dilute solution of n‐hexanol by the isothermal crystallization condition or the self‐seeding method. Hexagonal‐shaped lamellar crystals with and without spiral growth were obtained, and the crystals produced well‐resolved electron diffraction diagrams. The chain‐packing structure and morphological complexity in lamellar crystals were investigated by bright‐field and dark‐field diffraction contrast methods of transmission electron microscopy. Based on both diffraction contrast images, it was revealed that both tightly and loosely chain‐packing regions exist in one lamellar crystal. Thus, it was emphasized that PCL solution‐grown lamellar single crystals consist of micro‐crystals with nano‐order size for the crystalline core region. Lipase type XIII from Pseudomonas sp was used for the enzymatic degradation of the PCL lamellar crystals. Enzymatic degradation progressed perpendicularly from the crystal lateral sides, without decrease of the molecular weight and lamellar thickness, yielding notched‐shaped morphologies to the crystals. These results further indicate that PCL lamellar crystals consist of nano‐order micro‐crystals, and that enzyme hydrolyzes the loosely chain‐packing regions between the tightly chain‐packing regions (micro‐crystal regions). © 2002 Society of Chemical Industry

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Section: Resultssupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Morphology and enzymatic degradation of poly(ϵ‐caprolactone) single crystals: does a polymer single crystal consist of micro‐crystals?

Iwata

Doi

2002

Polymer International

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“…The lamellar thickness of PES lozenge-shaped crystals is about 7-8 nm as measured by AFM (image not shown). Taking the fiber repeat of 0.833 nm 1,5,6 and molecular weights into consideration, the chain-foldings occur at the lamellar surfaces of PES single crystals as is the case for biodegradable polyesters of P([R]-3HB), [12][13][14][15][16][17][18] P([R]-3HV), 28 PLLA, 23 etc. These results indicate that the average direction of chain-folding occurred along the lateral growth plane.…”

Section: Resultsmentioning

confidence: 99%

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

Iwata¹,

Doi²,

Isono³

et al. 2001

Macromolecules

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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.

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“…[25] Recently, enzymatic degradation of P(3HB) single crystals after annealing has been reported to yield crystal fragments along the long axis of crystal, [26] suggesting that the straight degradation pathways are inherent in P(3HB) single crystals, even after annealing process.…”

Section: Enzymatic Degradation Behaviors and Plausible Structures Of mentioning

confidence: 99%

Atomic Force Microscopy Investigation of Poly[(R)-3-hydroxybutyrate] Lamellar Single Crystals: Relationship between Molecular Weight and Enzymatic Degradation Behavior

Murase

Iwata

Doi³

2001

Macromol. Biosci.

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Enzymatic degradation behavior of a lamella of single crystals of poly(R)‐3‐hydroxybutyrate (P(3HB)) with an extracellular polyhydroxybutyrate (PHB) depolymerase purified from Alcaligenes faecalis T1 has been investigated by atomic force microscopy (AFM) in order to obtain further information for the chain packing state of P(3HB) in a lamellar single crystal. Two kinds of P(3HB) single crystals with different molecular weights, denoted respectively as H‐ and L‐P(3HB) for high and low molecular weights, respectively, were prepared. The enzymatic treatment was conducted for P(3HB) single crystals adsorbed on a surface of highly ordered pyrolytic graphite. The enzymatic degradation of both P(3HB) single crystals generates several crevices crosswise across the crystal at an early stage. Subsequently, the enzymatic degradation yields numbers of cracks lengthwise along the crystal. In addition to these common features, the interval between cracks crosswise across a lamella in H‐P(3HB) single crystal is longer than that in L‐P(3HB) single crystal, and each crack has V‐shaped and rectangular shaped morphology for H‐ and L‐P(3HB) single crystals, respectively. Based on these results, it is concluded that a lamella of P(3HB) single crystal has straight degradation pathways, that may correspond to a switchboard region, along the long axis of the crystal, independent of molecular weight of P(3HB) samples, and that a H‐P(3HB) single crystal has broader degradation pathways with longer intervals crosswise across the crystal than a L‐P(3HB) single crystal.

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Visualization of the Recrystallization of Solution-Grown Poly[(R)-3-hydroxybutyrate] Lamellar Crystals

Cited by 8 publications

References 6 publications

Morphology and enzymatic degradation of poly(ϵ‐caprolactone) single crystals: does a polymer single crystal consist of micro‐crystals?

Morphology and enzymatic degradation of poly(ϵ‐caprolactone) single crystals: does a polymer single crystal consist of micro‐crystals?

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

Atomic Force Microscopy Investigation of Poly[(R)-3-hydroxybutyrate] Lamellar Single Crystals: Relationship between Molecular Weight and Enzymatic Degradation Behavior

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