Controlled crystal nucleation in the melt-crystallization of poly(l-lactide) and poly(l-lactide)/poly(d-lactide) stereocomplex

Urayama, Hiroshi; Kanamori, Takeshi; Fukushima, Kazuki; Kimura, Yoshiharu

doi:10.1016/s0032-3861(03)00583-4

Cited by 182 publications

(148 citation statements)

References 14 publications

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“…The lower temperature side can be reasonably attributed to the sc crystallization and the higher temperature side to the hc crystallization, as reported previously. [9] The melting peaks of the sc crystals are much larger than those observed in the first run. The melting endotherm of the hc crystals becomes considerably small in BF5.…”

Section: Resultsmentioning

confidence: 83%

“…[8] Our group has previously reported the latter means where a certain organic phosphate complex was utilized as a crystal nucleator that can suppress the hc crystallization rather than enhance sc crystallization. [9] On the other hand, A-B block copolymers are usually used as compatibilizers to control the miscibility of the corresponding bicomponent polymer blends. With this idea extended, the newly developed strereoblock poly(lactic acid) (sb-PLA), a multi-block copolymer of PLLA and PDLA, can also serve as a compatibilizer to enhance the miscibility of PLLA and PDLA in their blend.…”

Section: Full Papermentioning

confidence: 99%

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Enhanced Stereocomplex Formation of Poly(L‐lactic acid) and Poly(D‐lactic acid) in the Presence of Stereoblock Poly(lactic acid)

Fukushima

Chang

Kimura

2007

Macromolecular Bioscience

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117

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Stereoblock poly(lactic acid) (sb-PLA) is incorporated into a 1:1 polymer blend system of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) that has a high molecular weight to study its addition effect on the stereocomplex (sc) formation of PLLA and PDLA. The ternary polymer blend films are first prepared by casting polymer solutions of sb-PLA, PLLA, and PDLA with different compositions. Upon increasing the content of sb-PLA in the blend films the sc crystallization is driven to a higher degree, while the formation of homo-chiral (hc) crystals is decreased. Lowering the molecular weight of the incorporated sb-PLA effectively increases the sc formation. Consequently, it is revealed that sb-PLA can work as a compatibilizer to improve the poor sc formation in the polymer blend of PLLA and PDLA.

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Section: Resultsmentioning

confidence: 83%

Section: Full Papermentioning

confidence: 99%

Enhanced Stereocomplex Formation of Poly(L‐lactic acid) and Poly(D‐lactic acid) in the Presence of Stereoblock Poly(lactic acid)

Fukushima

Chang

Kimura

2007

Macromolecular Bioscience

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117

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“…Table II shows some results together with the characteristics of the produced polymers. 22 The most preferable PLLA/PDLA ratio is in the range from 85/15 to 15/ 85 where the resultant diblock sb-PLAs show almost exclusive sc formation without the hc crystallization occurring. The shorter and longer blocks of these copolymers must be synthesized in steps 1 and 3, respectively, because the prepolymer first prepared in steps 1 and 2 can be well solvated by the larger amount of lactide monomer with opposite chirality and promote the chain elongation from its terminal in step 3.…”

Section: Rop Route To Sb-plamentioning

confidence: 99%

“…Therefore, various trials have been done for improving the miscibility of PLLA and PDLA. 22 Among them, making block copolymers of PLLA and PDLA, i.e., stereoblock-type poly(lactic acid)s (sb-PLA), has been found highly effective for generating the stereocomplex, because the neighboring D-and L-stereosequences can readily interact with each other to fall into molecular mixing state. 23 …”

Section: Development Of Stereoblock-type Poly-lactidesmentioning

confidence: 99%

Molecular, Structural, and Material Design of Bio-Based Polymers

Kimura

2009

Polym. J.

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Bio-based polymers are made from bio-originated feedstocks. Among those developed thus far, polylactides (PLA) stand at the forefront of practical use and are now manufactured on a commercial scale. However, the application of PLAs has been rather limited because of their higher cost, inferior thermal and mechanical properties, and worse processability as compared to the conventional oil-based polymers. Much effort has therefore been made to address it. Our major approach is to develop a direct polycondensation method to synthesize PLA and to use stereoblock-type PLA (sb-PLA) consisting of enantiomeric poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) because it can easily form stereocomplex (sc) showing a high melting temperature. Other specialty bio-based polymers are also synthesized for application to high-value fields. Particularly, with amphiphilic copolymers consisting of PLA and poly(oxyethylene) (PEG), new morphology change and sol-gel process have been disclosed. New bio-based polymers consisting of bio-derived monomeric units have also been synthesized to demonstrate their special functions. In addition, molecular and material design has been done with other biobased polymers such as poly(butylene succinate) (PBS) and poly(3-hydroxyalkanoate)s (PHA).

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“…[2] Therefore, various studies have been reported for improving the miscibility of PLLA and PDLA. [3,4] Yui et al reported preferable formation of sc crystals using a stereoblock copolymer (sb-PLA) of PLLA and PDLA in which both the enantiomeric segments are neighbored to make the sc formation easier. [5] Fukui and Yamane reported that sc-PLA can be efficiently formed when PLLA and PDLA are melt-blended at temperature slightly higher than T m of hc crystals.…”

Section: Introductionmentioning

confidence: 99%

Formation of Crystallosolvates Comprising Nano‐Crystals of Stereocomplex in a Ternary Mixture of Poly(L‐lactide)/Poly(D‐lactide)/Diphenyl Ether

Nakajima

Wataoka

Ohara

et al. 2009

Macro Chemistry & Physics

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Equal amounts of poly(L‐lactide) (PLLA) and poly(D‐lactide) (PDLA) were mixed with diphenyl ether (DE) at high temperature in DE‐to‐polymer composition from 0 to 80 wt.‐%. Cooling of the ternary mixtures produced white crystallosolvates without deposition of DE. Various analyses revealed that the crystallosolvates consisted of both homo‐chiral (hc) and stereocomplex (sc) crystals of PLLA and PDLA as well as amorphous domains involving DE. The crystallosolvate obtained at a DE content of 80 wt.‐%, comprised only the sc crystals. Atomic force microscopy (AFM) revealed that many granules having a size of 20 nm in diameter were formed from rod‐like hc crystallites and that the DE was slightly phase‐separated to form nano‐sized reservoirs. The stronger sc interaction between the PLLA and PDLA chains excluded DE from the polymer matrix.

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Controlled crystal nucleation in the melt-crystallization of poly(l-lactide) and poly(l-lactide)/poly(d-lactide) stereocomplex

Cited by 182 publications

References 14 publications

Enhanced Stereocomplex Formation of Poly(L‐lactic acid) and Poly(D‐lactic acid) in the Presence of Stereoblock Poly(lactic acid)

Enhanced Stereocomplex Formation of Poly(L‐lactic acid) and Poly(D‐lactic acid) in the Presence of Stereoblock Poly(lactic acid)

Molecular, Structural, and Material Design of Bio-Based Polymers

Formation of Crystallosolvates Comprising Nano‐Crystals of Stereocomplex in a Ternary Mixture of Poly(L‐lactide)/Poly(D‐lactide)/Diphenyl Ether

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