Highly Reinforced Poly(lactic acid) Foam Fabricated by Formation of a Heat-Resistant Oriented Stereocomplex Crystalline Structure

Li, Ruiguang; Zhao, Xiaowen; Coates, Phil; Caton‐Rose, Fin; Ye, Lin

doi:10.1021/acssuschemeng.1c04862

Cited by 27 publications

(26 citation statements)

References 30 publications

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“…Sc crystals make cell morphology more diverse in different processing methods, and the cell structure can be enhanced and controlled by controlling PDLA content. [27,39,51,[55][56][57][58][59][60][61][62] In this review, the cell structure and properties of porous PLA materials prepared by different methods are reviewed. The regulation of all kinds of cell morphologies and the influence of Sc crystallization on the internal cell network are mainly introduced, and the rules between the change of structure and the improvement of performance are summarized.…”

Section: Introductionmentioning

confidence: 99%

Review on Cell Structure Regulation and Performances Improvement of Porous Poly(Lactic Acid)

Hou

Pan

Zhou

et al. 2023

Macromol. Rapid Commun.

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Recent advances in the cell structure regulation and performances improvement of porous poly(lactic acid) materials (PPMs) are systematically reviewed in this feature article. First, the typical processing methods, including template method, non‐solvent induced phase separation, freeze–drying, and supercritical CO2 foaming, of PPMs are introduced emphatically. Their various cell morphologies by different processing methods are summarized: finger–like, honeycomb–like, fiber–like, through cell, open cell, closed cell, ball–like, and flower–like. Meanwhile, the transformation among different cell morphologies as well as the changes in cell size and cell density, having impact on the performances, is described. Second, the influence of stereo–complex crystals on the cell structure of PPMs is emphatically reviewed. Furthermore, the relationships between cell structure and properties that includes mechanical properties, thermal stability, heat insulation, and hydrophobicity, are elaborated. Eventually, the issues of PPMs worthy of further study are discussed.

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Section: Introductionmentioning

confidence: 99%

Review on Cell Structure Regulation and Performances Improvement of Porous Poly(Lactic Acid)

Hou

Pan

Zhou

et al. 2023

Macromol. Rapid Commun.

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“…11,12 Nevertheless, PLA exhibits low viscoelasticity at the processing temperature due to its linear structure and slow crystallization kinetics, negatively affecting cell growth and uniformity in the foaming process. 13 In recent times, some methods have been developed to improve the foaming behavior of PLA, including chain extension, 14,15 incorporation of nucleators or nanoparticles, 16−18 blending with other polymer materials, etc. 19−23 But the abovementioned approaches failed to significantly improve the mechanical properties of PLA foams.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Polymer foams, like polystyrene, polypropylene, polyurethane, etc., which possess properties of lightweight, high specific strength, and energy absorption, are widely applied in the fields of packaging, building, transportation, etc. However, the difficulty in their degradation and recycling brings about a petrochemical energy crisis and ecological environment problems, while biodegradable polymer foams have attracted widespread attention. − Poly(lactic acid) (PLA), as a biodegradable aliphatic polyester, is considered as the most promising sustainable substitute for petroleum-based polymers due to its superior mechanical properties, biocompatibility, and processing ability. − Supercritical CO 2 (sc-CO 2 ) batch foaming is an efficient way to prepare PLA foams. , Nevertheless, PLA exhibits low viscoelasticity at the processing temperature due to its linear structure and slow crystallization kinetics, negatively affecting cell growth and uniformity in the foaming process . In recent times, some methods have been developed to improve the foaming behavior of PLA, including chain extension, , incorporation of nucleators or nanoparticles, − blending with other polymer materials, etc. − But the abovementioned approaches failed to significantly improve the mechanical properties of PLA foams.…”

Section: Introductionmentioning

confidence: 99%

Construction of a Highly Oriented Poly(lactic acid)-Based Block Polymer Foam and Its Self-Reinforcing Mechanism

Kong

Zhao

et al. 2023

ACS Sustainable Chem. Eng.

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Developing poly(lactic acid) (PLA)-based biodegradable polymer foams with high performance is crucial for sustainable energy conservation and the ecological environment. In this work, by applying poly(lactide-co-caprolactone) (PLCL) as a compatibilizer, the block polymer of poly(l-lactic) acid (PLLA)-b-polycaprolactone (PCL) with a long-chain branched structure was prepared by reactive processing. By utilizing the difference between the glass-transition temperature (T g) and melting temperature (T m) of PLA and PCL, PLLA-b-PCL-PLCL foams with a PCL chain as the foaming phase and an oriented PLLA chain as the enhancing phase were prepared by establishing a solid-phase hot drawing@supercritical CO2 foaming method. The incorporation of PLCL links significantly improved the interfacial compatibility between PLLA and PCL phases and chain entanglements, exhibiting strain-hardening behavior and leading to an improvement in the stretchability of the block polymer. In the hot drawing process in the range of T g(PLA)–T m(PLA), both PLLA and PCL phases were elongated along the drawing direction, and with an increasing draw ratio, the orientation factor and the crystallinity of the two phases increased evidently, accompanied by the formation of a shish–kebab crystalline structure. In the subsequent foaming process in the range of T g(PCL)–T m(PCL), the molecular chains of the PLLA phase were frozen and the retention of the orientation factor reached over 90%, while under CO2, crystallinity and crystallite size increased and a more perfect crystalline structure formed for the PCL phase. With an increasing draw ratio, the saturated dissolved amount of CO2 increased and the cell density and cell size of foam reached 5.13 × 109 cells/cm3 and 4.06 μm, respectively. The fibrillar structures of the PLLA phase appeared on the cell wall, while the tensile strength and modulus of foam reached as high as 65.9 MPa and 1.01 GPa, respectively. As a result, a super-strong PLA-based microcellular foam with dense micropores and highly oriented microfibrillar structures was constructed.

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“…Poly(lactic acid) (PLA) fiber, also known as “corn fiber”, is a kind of “green” fiber, which is manufactured through electrostatic spinning, solution spinning, or melt-spinning of the PLA resin. − Due to the excellent biocompatibility, complete biodegradability, and high mechanical strength, it has been widely used in the biomedical field as a surgical suture, a ligament-strengthening device, a scaffold for tissue engineering, and so on. However, for the PLA fiber, due to the poor crystallization ability, it always shows an imperfectly oriented crystalline structure with a low degree of anisotropy, leading to a low axial negative expansion coefficient.…”

Section: Introductionmentioning

confidence: 99%

Construction of Twisted/Coiled Poly(lactic acid) Fiber-Based Artificial Muscles and Stable Actuating Mechanism

Kong

et al. 2022

ACS Sustainable Chem. Eng.

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Exploring artificial muscles based on renewable, biodegradable, and biocompatible polymer fibers is essential to broaden their applications in biomedicine and bionic fields. In this work, by constructing a poly(l-lactic acid) (PLLA)/poly(d-lactic acid) (PDLA) stereo-complex, PLA-based as-spun fibers were prepared by melt-spinning, while stretching orientation and annealing processes were further employed to improve the molecular anisotropy of the fibers (PLLA/D-S-A). On this basis, PLLA/D-S-A fiber-based artificial muscles were fabricated by twisting, coiling, and two-step heat setting. With the increase of twisting density/coiling diameter and decrease of merging strand numbers, the spring index as well as the actuating contraction strain of the artificial muscle increased. After initial training, the cyclic shrinkage–recovery process of the artificial muscle was stable, and the contraction strain remained at about 15.30% under 8 V electric stimulus by applying a load with 50 times the artificial muscle weight, exhibiting a high actuating cyclic stability. The high orientation degree in both the crystalline and amorphous regions of the PLLA/D-S-A fiber ensured a high axial negative expansibility under external stimuli, resulting in high actuating contraction strain for artificial muscles. Meanwhile, the perfect oriented crystalline structures endowed fibers with high thermal stability, and the crystallinity, contents of amorphous phase and mesophase, and the crystalline size changed slightly at the actuation temperature, which was conducive to achieving high circulatory stability for artificial muscles. Such PLA-based artificial muscles display promising applications as soft actuators in tissue engineering, healthcare, and so on.

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Highly Reinforced Poly(lactic acid) Foam Fabricated by Formation of a Heat-Resistant Oriented Stereocomplex Crystalline Structure

Cited by 27 publications

References 30 publications

Review on Cell Structure Regulation and Performances Improvement of Porous Poly(Lactic Acid)

Review on Cell Structure Regulation and Performances Improvement of Porous Poly(Lactic Acid)

Construction of a Highly Oriented Poly(lactic acid)-Based Block Polymer Foam and Its Self-Reinforcing Mechanism

Construction of Twisted/Coiled Poly(lactic acid) Fiber-Based Artificial Muscles and Stable Actuating Mechanism

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