Thermal Properties and Structural Evolution of Poly(<scp>l</scp>-lactide)/Poly(<scp>d</scp>-lactide) Blends

Feng, Lidong; Bian, Xinchao; Li, Gao; Chen, Xuesi

doi:10.1021/acs.macromol.1c01866

Cited by 39 publications

(32 citation statements)

References 85 publications

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“…However, PLDLA- m with a low l -lactate unit content has strong hydrogen-bonding interactions with PLLA, leading to potentially varying compatibility with PLLA. The compatibility and morphology of PLLA/PDLA blends is explained in our previous work …”

Section: Resultsmentioning

confidence: 99%

“…The compatibility and morphology of PLLA/PDLA blends is explained in our previous work. 64 Morphology of PLLA/PLDLA Blends. The compatibility of a binary polymer blend can be directly observed by the morphology.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The stereocomplexed PLA (sc-PLA) for an equimolar blend of enantiomeric PLLA and PDLA has a melting temperature of 230–254 °C, and can potentially be applied in the field of special engineering plastics due to its high heat resistance. − Crystallizations of homo-PLA and sc-PLA are competitive in PLLA/PDLA blends, and sc-PLA crystals acting as nucleating agents can also affect the crystallization behavior of homo-PLA. − The properties of PLLA/PDLLA blends, including their miscibility, − crystallinity, ,,, mechanical properties, , morphology, ,, hydrolysis, − and biodegradability have also been studied extensively. It has been reported that PLLA and PDLLA are imperfectly miscible; consequently, double T g s and phase-separation behaviors have been detected by many researchers. ,,, Shao et al found that the phase separation between PLLA and PDLA in PLLA/PDLA blends not only depends on their respective molecular weights but also relies on the optical purity of the polymers. Li et al reported a PLLA/PDLA/PDLLA blend that showed a single T g , and they thus considered the components to be completely compatible.…”

Section: Introductionmentioning

confidence: 99%

“…It has been reported that PLLA and PDLLA are imperfectly miscible; consequently, double T g s and phase-separation behaviors have been detected by many researchers. 54,57,63,64 Shao et al 65 found that the phase separation between PLLA and PDLA in PLLA/PDLA blends not only depends on their respective molecular weights but also relies on the optical purity of the polymers. Li et al 66 reported a PLLA/PDLA/PDLLA blend that showed a single T g , and they thus considered the components to be completely compatible.…”

Section: ■ Introductionmentioning

confidence: 99%

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Compatibility and Thermal and Structural Properties of Poly(l-lactide)/Poly(l-co-d-lactide) Blends

Feng

Bian

et al. 2022

Macromolecules

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To explicate the interaction processes between poly(l-lactide) (PLLA) and poly(l-co-d-lactide) (PLDLA) in their blends, a series of high-molecular-weight PLDLA-m polymers (where m represents the percentage of l-lactate units) were prepared by ring-opening polymerization at different feed ratios of l- to d-lactides and blended with highly optically pure PLLA by solution blending. The compatibility and thermal and structural properties of the PLLA/PLDLA-m blends were investigated by differential scanning calorimetry (DSC) and field emission scanning electron microscopy (FE-SEM) in detail. The PLLA/PLDLA-m blends with m = 60–20 wt % were only partially compatible because obviously double glass transitions were detected in DSC curves and multiphase structures were observed in SEM micrographs. The compatibility between PLLA and PLDLA-m decreased as the l-lactate unit content in PLDLA-m decreased. Crystallization of the PLLA phase in the PLLA/PLDLA-m blends was restricted by PLDLA-m at m = 95–40 wt % (the restriction was strongest at m = ∼70 wt %); however, it was enhanced as the l-lactate unit content decreased at m ≤ 40 wt %. The PLLA/PLDLA-m blends demonstrated weak-to-strong hydrogen-bonding interactions as the l-lactate unit content decreased at m ≤ 80 wt %. The PLLA/PLDLA-m blends can form not only a eutectic but also individual crystal structures of PLLA and PLDLA-m at m ≥ 80 wt %, while the formation of individual crystals of PLLA, PLDLA-m, and stereocomplexed polylactide (sc-PLA) is favored at m ≤ 15 wt %.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Compatibility and Thermal and Structural Properties of Poly(l-lactide)/Poly(l-co-d-lactide) Blends

Feng

Bian

et al. 2022

Macromolecules

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“…As compared with PLLA/PDLA/2EG and PLLA/PDLA/3EG blends, more SC crystallites are formed in the crystallization of It has been well established that the survival of alternately arranged PLLA/PDLA chain segments in PLLA/PDLA blend melts plays a key role in their SC crystallization process because they can serve as a nucleation precursor to accelerate crystallization and stimulate exclusive SC formation [28,63]. In general, complete melting of high-MW PLLA/PDLA blends could lead to the separation of enantiomeric PLA chains into PLLAand PDLA-rich domains, thus the SC formation in the phase-separated melts is kinetically limited by the prolonged chain diffusion pathway as compared with the formation of HCs [21,64]. However, the multi-arm stereo-block PLA copolymers could behave as compatibilizers to effectively suppress the separation of the ordered PLLA/PDLA segment assemblies, probably because their long PLA arms can readily interact with the PLLA and PDLA segments.…”

Section: Crucial Role Of the Arm Number Of Multi-arm Stereo-block Pla Copolymers In Enhancing Sc Crystallizability Of Plla/pdla Blendsmentioning

confidence: 99%

Substantially Enhanced Stereocomplex Crystallization of Poly(L-lactide)/Poly(D-lactide) Blends by the Formation of Multi-Arm Stereo-Block Copolymers

et al. 2022

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Stereocomplex-type polylactide (SC-PLA) created by alternate packing of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) chains in a crystalline state has emerged as a growingly popular engineering bioplastic that possesses excellent hydrolytic stability and thermomechanical properties. However, it is extremely difficult to acquire high-performance SC-PLA products via melt-processing of high-molecular-weight PLLA/PDLA blends because both SC crystallites and homocrystallites (HCs) are competitively formed in the melt-crystallization. Herein, a facile yet powerful way was employed to boost SC formation by introducing trace amounts of some epoxy-functionalized small-molecule modifiers into the enantiomeric blends during reactive melt-blending. The results show that the SC formation is considerably enhanced with the in situ generation of multi-arm stereo-block PLA copolymers, based on the reaction between epoxy groups of the modifiers and hydroxyl end groups of PLAs. More impressively, it is intriguing to find that the introduction of only 0.5 wt% modifiers can induce exclusive SC formation in the blends upon isothermal and non-isothermal melt-crystallizations. The outstanding SC crystallizability might be attributed to the suppressing effect of such unique copolymers on the separation of the alternately arranged PLLA/PDLA chain segments in molten state as a compatibilizer. Furthermore, the generation of these copolymers does not result in a significant increase in melt viscosity of the blends. These findings suggest new opportunities for the high-throughput processing of SC-PLA materials into useful products.

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Poly(Lactic Acid): Recent Stereochemical Advances and New Materials Engineering

Hu,

Zhang,

Pang

et al. 2024

Advanced Materials

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Poly(lactic acid) (PLA) is a representative biobased and biodegradable aliphatic polyester and a front‐runner among sustainable materials. As a semicrystalline thermoplastic, PLA exhibits excellent mechanical and physical properties, attracting considerable attention in commodity and medical fields. Stereochemistry is a key factor affecting PLA's properties, and to this end, the engineering of PLA's microstructure for tailored material properties has been an active area of research over the decade. This Review first covers the basic structural variety of PLA. A perspective on the current states of stereocontrolled synthesis as well as the relationships between the structures and properties of PLA stereosequences are included, with an emphasis on record regularity and properties. At last, state‐of‐the‐art examples of high‐performance PLA‐based materials within an array of applications are given, including packaging, fibers, and textiles, healthcare and electronic devices. Among various stereo‐regular sequences of PLA, poly(L‐lactic acid) (PLLA) is the most prominent category and has myriad unique properties and applications. In this regard, cutting‐edge applications of PLLA are mainly overviewed in this review. At the same time, new materials developed based on other PLA stereosequences are highlighted, which holds the potential to a wide variety of PLA‐based sustainable materials.

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Thermal Properties and Structural Evolution of Poly(l-lactide)/Poly(d-lactide) Blends

Cited by 39 publications

References 85 publications

Compatibility and Thermal and Structural Properties of Poly(l-lactide)/Poly(l-co-d-lactide) Blends

Compatibility and Thermal and Structural Properties of Poly(l-lactide)/Poly(l-co-d-lactide) Blends

Substantially Enhanced Stereocomplex Crystallization of Poly(L-lactide)/Poly(D-lactide) Blends by the Formation of Multi-Arm Stereo-Block Copolymers

Poly(Lactic Acid): Recent Stereochemical Advances and New Materials Engineering

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