Enhanced crystallization rate and mechanical properties of poly(<scp>l</scp>‐lactic acid) by stereocomplexation with four‐armed poly(<i>ϵ</i>‐caprolactone)‐<i>block</i>‐poly(<scp>d</scp>‐lactic acid) diblock copolymer

Ning, Zhenbo; Liu, Junjie; Jiang, Ni; Gan, Zhihua

doi:10.1002/pi.5352

Cited by 9 publications

(10 citation statements)

References 34 publications

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“…The effect of star-shaped copolymers seems to be different compared to that in our earlier work [ 16 ], in which the rate of PLLA crystallization was accelerated by the addition of star-shaped block copolymers. Actually, the temperatures to remove the thermal history in the two papers were different.…”

Section: Resultscontrasting

confidence: 84%

“…The copolymer of PCL and PLA can enhance the interfacial adhesion between the two phases and is used as a compatibilizer for the PLLA/PCL blend [ 14 ]. In recent years, copolymers or composites with soft middle blocks and outer PDLA blocks have been a hotspot of scientific interest as PLLA modifiers [ 7 , 15 , 16 ]. In these modifiers, the soft middle segments could be a PCL copolymer and introduce elastic properties into the material [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

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Crystallization and Alkaline Degradation Behaviors of Poly(l-Lactide)/4-Armed Poly(ε-Caprolactone)-Block-Poly(d-Lactide) Blends with Different Poly(d-Lactide) Block Lengths

et al. 2020

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Four-armed poly(ε-caprolactone)-block-poly(d-lactide) (4-C-D) copolymers with different poly(d-lactide) (PDLA) block lengths (Mn,PDLAs) were synthesized by sequential ring-opening polymerization (ROP). The formation of stereocomplex (SC) crystallites in the 80/20 poly(l-lactide) (PLLA)/4-C-D blends were investigated with the change of Mn,PDLA from 0.5 to 1.5 kg/mol. It was found that the crystallization and alkaline degradation of the blends were profoundly affected by the formed SC crystallites. The PLLA/4-C-D0.5 blend had the lowest crystallization rate of the three blends, and it was difficult to see spherulites in this blend by polarized optical microscopy (POM) observation after isothermal crystallization at 140 °C for 4 h. Meanwhile, when Mn,PDLA was 1 kg/mol or 1.5 kg/mol, SC crystallites could be formed in the PLLA/4-C-D blend and acted as nucleators for the crystallization of PLLA homo-crystals. However, the overall crystallization rates of the two blends were still lower than that of the neat PLLA. In the PLLA/4-C-D1.5 blend, the Raman results showed that small isolated SC spherulites were trapped inside the big PLLA homo-spherulites during isothermal crystallization. The degradation rate of the PLLA/4-C-D blend decreased when Mn,PDLA increased from 0.5 to 1.5 kg/mol, and the degradation morphologies had a close relationship with the crystallization state of the blends. This work revealed the gradual formation of SC crystallites with the increase in Mn,PDLA in the PLLA/4-C-D blends and its significant effect on the crystallization and degradation behaviors of the blend films.

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Section: Resultscontrasting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Crystallization and Alkaline Degradation Behaviors of Poly(l-Lactide)/4-Armed Poly(ε-Caprolactone)-Block-Poly(d-Lactide) Blends with Different Poly(d-Lactide) Block Lengths

et al. 2020

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“…1,6 Furthermore, they can accelerate the crystallization rate of PLLA. 3,8 However, when the SC strategy is used, the enhanced overall crystallization of a PLLA blend could also make the material more brittle, 9 and SC crystallites also exhibit a much slower hydrolytic/enzymatic degradation rate. 10 As a result, it is very important to extend the use of PLA materials with controllable sterecomplexation and degradation rate.…”

Section: Introductionmentioning

confidence: 99%

Relationship between crystallization state and degradation behavior of poly(l‐lactide)/four‐armed poly(d,l‐lactide)‐block‐poly(d‐lactide) blends with different poly(d‐lactide) block lengths

Dai

Jiang

Ning

et al. 2020

Polymer International

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A series of four-armed poly(D,L-lactide)-block-poly(D-lactide) (4-DL-D) copolymers were synthesized by ring-opening polymerization. By fixing the poly(D,L-lactide) (PDLLA) block length (1 kg mol −1 ) and changing the poly(D-lactide) (PDLA) block length (M n,PDLA = 0, 0.5, 1.1, 1.3, 1.8 and 2.6 kg mol −1 ), the crystallization and alkaline degradation of the PLLA/4-DL-D blends were investigated. The four-armed PDLLA core of the copolymer inhibited the crystallization of PLLA, while the outer PDLA block could affect the crystallization differently when its length changed. If M n,PDLA was 0 or 0.5 kg mol −1 , the crystallization of PLLA in the PLLA/4-DL-D blend was retarded markedly and the degradation rate of the blend films was much faster than that of neat PLLA film. Interestingly, when M n,PDLA was 1.1 kg mol −1 or higher, stereocomplex (SC) crystallites with different morphologies were formed, and the degradation rate of the PLLA/4-DL-D blend decreased gradually with increasing M n,PDLA . In the PLLA/4-DL-D1.1 blend, the SC crystallites acted as nucleators for PLLA homocrystallites, while in the PLLA/4-DL-D1.3 blend, small isolated SC crystallites were observed inside the PLLA homospherulites. When M n,PDLA was 1.8 or 2.6 kg mol −1 , a network structure of SC crystallites was formed and the degradation resistance of the films was markedly enhanced. A possible isothermal crystallization mechanism was proposed for the PLLA/4-DL-D blends, and the relationship between the crystallization state and degradation behavior was explored. This work revealed that the crystallization state, which was controlled by the PDLA block length, had a significant effect on the degradation behavior of PLLA/4-DL-D blend films.

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“…This behaviour also implies that PEG is compatible with PLLA as its plasticizing efficiency is closely bound up with its compatibility with PLLA . This improved miscibility between flexible PEG and PLLA is beneficial for enhancing the toughness of PLLA, making easier its shaping, flexing and moulding . As the PEG content exceeded 20 wt%, the PEG/PLLA blend became brittle (i.e.…”

Section: Resultsmentioning

confidence: 94%

The effect of poly(ethylene glycol) mixed with poly(l‐lactic acid) on the crystallization characteristics and properties of their blends

Athanasoulia

Christoforidis

Korres

et al. 2019

Polymer International

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The non‐isothermal and isothermal crystallizations of extruded poly(l‐lactic acid) (PLLA) blends with 10, 20 and 30 wt% poly(ethylene glycol) (PEG) were investigated with differential scanning calorimetry. The formation of α‐form crystals in the blend films was verified using X‐ray diffraction and an increase in crystallinity indexes using Fourier transformation infrared spectroscopy. Crystallization and melting temperatures and crystallinity of PLLA increased with decreasing cooling rate (CR) and showed higher values for the blends. Although PLLA crystallized during both cooling and heating, after incorporation of PEG and with CR = 2 °C min−1 its crystallization was completed during cooling. Increasingly distinct with CR, a small peak appeared on the lower temperature flank of the PLLA melting curve in the blends. A three‐dimensional nucleation process with increasing contribution from nuclei growth at higher CR was verified from Avrami analysis, whereas Kissinger's method showed that the diluent effect of 10 and 20 wt% PEG in PLLA decreased the effective energy barrier. During isothermal crystallization, crystallization half‐time increased with temperature (Tic) for the blends, decreased with PEG content and was lower than that of pure PLLA. In addition, the Avrami rate constants were significantly higher than those of pure PLLA, at the lower Tic. Different crystal morphologies in the PLLA phase were formed, melting in a broader and slightly higher Tm range than pure PLLA. The crystallization activation energy of PLLA decreased by 56% after the addition of 10 wt% PEG, increasing though with PEG content. Finally, PEG/PLLA blends presented improved flexibility and hydrophilicity. © 2019 Society of Chemical Industry

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Enhanced crystallization rate and mechanical properties of poly(l‐lactic acid) by stereocomplexation with four‐armed poly(ϵ‐caprolactone)‐block‐poly(d‐lactic acid) diblock copolymer

Cited by 9 publications

References 34 publications

Crystallization and Alkaline Degradation Behaviors of Poly(l-Lactide)/4-Armed Poly(ε-Caprolactone)-Block-Poly(d-Lactide) Blends with Different Poly(d-Lactide) Block Lengths

Crystallization and Alkaline Degradation Behaviors of Poly(l-Lactide)/4-Armed Poly(ε-Caprolactone)-Block-Poly(d-Lactide) Blends with Different Poly(d-Lactide) Block Lengths

Relationship between crystallization state and degradation behavior of poly(l‐lactide)/four‐armed poly(d,l‐lactide)‐block‐poly(d‐lactide) blends with different poly(d‐lactide) block lengths

The effect of poly(ethylene glycol) mixed with poly(l‐lactic acid) on the crystallization characteristics and properties of their blends

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