Elevation of flow temperature of poly(l-lactic acid) gel by controlling its morphology and crystal form

Matsuda, Yasuhiro; Miyamoto, Kazuaki; Ashizawa, Hiroki; Fukui, Takahiro; Tasaka, Shigeru

doi:10.1007/s00289-017-1958-6

Cited by 8 publications

(10 citation statements)

References 19 publications

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“…Although the mechanism of the elevation of the flow temperature of the immersed gel should be elucidated from more experimental evidences for gels formed by solutions with different concentrations of PLLA‐ b ‐PS with various monomer compositions, a mechanism which can be conjectured from the experimental data shown in this paper is as follows. When the PLLA gel formed only by its ε‐crystals was heated slowly (<2 °C min −1 ), the ε‐crystals were changed to α‐crystals with poorer solubility than that of the ε‐crystals during the viscoelastic measurement, and the gel began to flow around 75 °C . On the other hand, when the PLLA gel was heated fast (>3 °C min −1 ), it began to flow around 45 °C, because the ε‐crystals dissolved in DMF before changing to α‐crystals.…”

Section: Resultsmentioning

confidence: 99%

“…When the PLLA gel formed only by its ε-crystals was heated slowly (<2 °C min −1 ), the ε-crystals were changed to α-crystals with poorer solubility than that of the ε-crystals during the viscoelastic measurement, and the gel began to flow around 75 °C. [21] On the other hand, when the PLLA gel was heated fast (>3 °C min −1 ), it began to flow around 45 °C, because the ε-crystals dissolved in DMF before changing to α-crystals.…”

Section: Morphology and Viscoelastic Behavior Of Plla Gel With Plla-bmentioning

confidence: 99%

“…[19] They attributed the excellent mechanical properties to the energy dissipation of the flexible network during fracture processes. [20] In our previous study, [21] the PLLA gel was immersed into DMF solution of PLLA to allow the PLLA chains to penetrate into the network of the fibrous structure of PLLA to increase the flow temperature of the PLLA gel. However, we needed to heat the PLLA/DMF solution around 40 °C to prevent the gelation of the solutions during the immersion of the gels, and heating the samples partially destroyed the fibrous structure.…”

Section: Introductionmentioning

confidence: 99%

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Fabrication of Polymer Structure among Fibrous Structure of Poly(lactic acid) Gel and Improvement of Physical Properties

Matsuda¹,

Ashizawa²,

Fukui³

et al. 2017

Macro Chemistry & Physics

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Polymer structure of a block copolymer of poly(l‐lactic acid) (PLLA) and polystyrene (PS) is formed among a fibrous structure of PLLA inducing the gelation of PLLA in N,N‐dimethylformamide (DMF). The results of static and dynamic light scattering show the formation and growth of aggregates of the block copolymer (PLLA‐b‐PS) to form aggregates in DMF. The gels formed by the fibrous structure of PLLA in DMF are immersed in DMF solutions of PLLA‐b‐PS to allow the PLLA‐b‐PS chains to penetrate among the fibrous structure. The morphology of PLLA‐b‐PS in the gel is observed by field emission scanning electron microscopy. Viscoelastic measurements of the gel before and after the immersion indicate that the structure of the PLLA‐b‐PS elevates the flow temperature.

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Section: Resultsmentioning

confidence: 99%

Section: Morphology and Viscoelastic Behavior Of Plla Gel With Plla-bmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fabrication of Polymer Structure among Fibrous Structure of Poly(lactic acid) Gel and Improvement of Physical Properties

Matsuda¹,

Ashizawa²,

Fukui³

et al. 2017

Macro Chemistry & Physics

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“…In another work, Matsuda et al described three procedures to elevate the flow temperature of PLLA gel. [ 89–92 ] In the first process, they took PLLA of higher molecular weight and prepared its gel in DMF. The obtained gel was immersed in a DMF solution of PLLA with lower molecular weight and cooled to a temperature of −18°C.…”

Section: Solvent‐induced Gel Formation In Pllamentioning

confidence: 99%

“…Flow temperature was also found to be enhanced by increasing the concentration of the solution to form the gel, followed by heating. [ 92 ] In order to elucidate the exchangeability and solubility of solvents to PLLA, they investigated the flow temperature of PLLA gels after exchanging DMF with variable solvents. The exchangeability of solvents was explained with the help of Hansen solubility parameters (HSPs).…”

Section: Solvent‐induced Gel Formation In Pllamentioning

confidence: 99%

Polylactide cocrystals and gels

2022

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Synthetic biodegradable polyesters have emerged as an alternative to conventional petroleum-derived polymers for a diverse range of applications. Among these, polylactides are the most commercially successful biodegradable polymers. The presence of stereoregular chains makes poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) semicrystalline. The blending of enantiomeric PLLA and PDLA resulted in the stereocomplex formation due to non-covalent interactions of enantiomeric chains. PLLA exhibits different crystalline forms depending on the crystallization conditions with different chain conformations, as well as different chain packing structures. PLLA and its blend with PDLA are known to form cocrystals with certain solvents. This review focuses mainly on the recent progress in understanding the cocrystal formation, polymorphic phase transitions of these cocrystals, gelation mechanism and stereocomplex formation in blend gels of polylactides.

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Elevation of Flow Temperature and Structural Change of Poly(Lactic Acid) Gel Induced by Formation of Stereocomplex Crystals

Matsuda

Kamizono

2023

Macromolecular Symposia

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Poly(lactic acid) gels formed from solutions of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA). X-ray diffraction patters indicate the formation of stereocomplex crystals for not only the gel formed from solution containing equimolar PLLA and PDLA, but also the gel formed from solution containing 9:1 of PLLA and PDLA. The flow temperatures of the gels were determined by viscoelastic measurements, and the morphologies of the dried gels were observed by field emission scanning electron microscopy. The flow temperatures of the gels from solutions containing both PLLA and PDLA were higher than those containing only PLLA. Network structures formed by uniformly distributed thin fibers, were observed for the gels formed from solutions with L:D ratios near the equimolar ratio. The dependency of the flow temperature and morphology on the polymer concentration and L:D ratio of the gels was discussed based on the experimental data.

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Elevation of flow temperature of poly(l-lactic acid) gel by controlling its morphology and crystal form

Cited by 8 publications

References 19 publications

Fabrication of Polymer Structure among Fibrous Structure of Poly(lactic acid) Gel and Improvement of Physical Properties

Fabrication of Polymer Structure among Fibrous Structure of Poly(lactic acid) Gel and Improvement of Physical Properties

Polylactide cocrystals and gels

Elevation of Flow Temperature and Structural Change of Poly(Lactic Acid) Gel Induced by Formation of Stereocomplex Crystals

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