Influence of different β-nucleation agents on poly(<scp>l</scp>-lactic acid): structure, morphology, and dynamic mechanical behavior

Su, Lele; Zou, Jun; Dong, Shengtao; Hao, Niyuan; Xu, Hongyao

doi:10.1039/c7ra10550a

Cited by 21 publications

(16 citation statements)

References 48 publications

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“…However, in the po-PLA and ha-PLA fibers diffraction patterns, new peaks appeared in the range of 2θ ≈ 23–32° while diffraction peaks corresponding to the α structure are not clearly observed; only in the case of po-PLA a very weak diffraction peak is shown at 2θ = 16.7° (200). In Figure 7 B, which is the amplification of the 2θ ≈ 23–32° range, it is clearly observed that these new diffraction peaks appearing at 2θ ≈ 25.8 and 26.3° for po-PLA and at 2θ ≈ 25.8, 26.3 and 28.1° for ha-PLA, corresponding to the β crystalline form [ 43 ].…”

Section: Resultsmentioning

confidence: 99%

Development of Highly Crystalline Polylactic Acid with β-Crystalline Phase from the Induced Alignment of Electrospun Fibers

et al. 2021

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Polylactic acid (PLA) is one of the known synthetic polymers with potential piezoelectric activity but this property is directly related to both the crystalline structure and crystalline degree. Depending on the process conditions, PLA can crystallize in three different forms: α-, β-, and γ- form, with β-crystalline phase being the piezoelectric one. To obtain this crystalline structure, transformation of α to β is required. To do so, the strategies followed so far consisted in annealing or/and stretching of previously obtained PLA in the form of films or fibers, that is, additional post-processing steps. In this work, we are able to obtain PLA fibers with high macromolecular alignment, as demonstrated by SEM, and in the β polymorph, as detected by X-ray diffraction (XRD) without the requirement of post-processing. For that, PLA fibers were prepared by using an electrospinning coupled to a drum collector. This set up and the optimization of the parameters (voltage flow-rate, and drum collector speed) induced molecular stretching giving rise to uniaxially oriented and highly aligned fibers.

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Section: Resultsmentioning

confidence: 99%

Development of Highly Crystalline Polylactic Acid with β-Crystalline Phase from the Induced Alignment of Electrospun Fibers

et al. 2021

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“…PLLA spectra exhibits a broad absorption peak in the range 3700-3600 cm −1 which is assigned to ν(O-H) vibration modes. Hydrogen association can easily occur in hydroxyl groups, resulting in a shift of the corresponding absorption peak to lower wavenumbers and a gradual widening with the increase of the association degree [21]. Furthermore, the two peaks at about 2951 and 3003 cm −1 correspond to the ν(C-H) vibration modes of methyl groups.…”

Section: Synthesis and Characterization Of Block Copolymersmentioning

confidence: 99%

New Biodegradable Poly(l-lactide)-Block-Poly(propylene adipate) Copolymer Microparticles for Long-Acting Injectables of Naltrexone Drug

et al. 2020

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In the present study, novel block copolymers of poly(l-lactide)-block-poly(propylene adipate) (PLLA-b-PPAd) were synthesized in two ratios, 90/10 and 75/25 w/w and were further investigated as long-acting injectable (LAI) polymeric matrices in naltrexone base microparticle formulations. The synthesized polymers were characterized by 1 H-NMR, 13 C-NMR, FTIR, XRD, TGA and DSC. NMR and FTIR spectroscopies confirmed the successful synthesis of copolymers while DSC showed that these are block copolymers with well-defined and separated blocks. Microparticles were prepared by single emulsification method and were further characterized. Nanoparticles in the range of 0.4-4.5 µm were prepared as indicated by SEM, with copolymers giving the lowest particle size. By XRD and DSC it was found that naltrexone was present in the amorphous state in its microparticles. Dissolution study showed a drug release extending over seven days, indicating that these novel PLLA-b-PPAd copolymers could be promising matrices for naltrexone's LAI formulations. It was evidenced that drug release depended on the copolymer composition. Model release studies showed that drug release is controlled by diffusion.Polymers 2020, 12, 852 2 of 24 as drug carriers are ε-polycaprolactone (PCL), poly(lactic acid) (PLA), poly(glycolic acid) (PGA), their copolymer poly(lactide-co-glycolide) (PLGA), which are typically prepared by ring-opening polymerizations, and polyesters resulting from the polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid such as poly(ethylene succinate), poly(ethylene adipate), poly(propylene adipate) (PPAd). Among them, PLA is by far the most extensively studied. However, the use of PLA suffers from some limitations due to its high crystallinity and low hydrolysis rate. Copolymerization is an easy method to modulate the properties of a polymer, by varying the rigidity/flexibility of polymer chains, the hydrophilic/hydrophobic balance and the amorphous/crystalline ratio [3]. Copolymerization of PLA with more hydrophilic and amorphous polymers has been carried out to modify the required biomaterial properties for specific applications [4].Naltrexone base (NTX) is a specific opioid antagonist, used in the treatment of both drug addiction and alcohol dependence. It is marketed in tablet form for oral administration but has some pharmacotherapeutic limitations (for example, a low oral bioavailability, as 98% of the drug is metabolized in the liver) and gastrointestinal side effects (nausea, abdominal pain, and vomiting). Treatment by oral administration of NTX requires a daily administration and its efficacy can be compromised due to the patient's non-compliance. Indeed, 37% of patients discontinue the daily oral use of NTX by 12 weeks and more than 80% discontinue its use by six months [5]. Currently there are two major types of sustained-release formulations for NTX delivery: (a) injectable depot formulations for long-acting release (Naltrel ® , Vivitrol ® , and Depotrex ® ), and (b) surgically implantable pellets (Pro...

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“…[ 56 ] Also, the PLLA IR spectrum exhibit characteristic bands attributable to CH stretch at 2998 and 2950 cm −1 , CO stretch at 1765 cm −1 , CO stretching vibration at 1100 cm −1 . [ 57–59 ]…”

Section: Resultsmentioning

confidence: 99%

“…[56] Also, the PLLA IR spectrum exhibit characteristic bands attributable to C-H stretch at 2998 and 2950 cm −1 , C=O stretch at 1765 cm −1 , C-O stretching vibration at 1100 cm −1 . [57][58][59] The IR spectrum of the PCL-b-PLLA diblock copolymer shown in Figure 4 exhibits a prominent band at 1758 cm −1 corresponding to C=O stretch for the PLLA segment and a shoulder band at 1728 cm −1 arising from the PCL block of the copolymer. The spectrum shows a clear shift in the absorption band values as compared to pristine PLLA and PCL which is in accordance with the reported literature.…”

Section: Ftir Of Pcl-b-plla Diblock Copolymermentioning

confidence: 99%

Synthesis, Optimal Fabrication, and Physico‐Mechanical Property Evaluation of PCL‐b‐PLLA Diblock Copolymer‐Based Nanoscale Roughness Textured Electrospun Mats

Sharma

Goel

Jacob

et al. 2021

Macro Materials & Eng

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Poly(ɛ-caprolactone)-block-poly(L-lactide) (PCL-b-PLLA) diblock copolymer and its electrospun mats (EMs) are characterized for their microstructural, thermal, and physico-mechanical properties. The EMs of synthesized copolymer exhibiting the optimal level of average fiber diameter (Co-FD) and diameter variation (Co-SD) are obtained following Taguchi's design of experiments (DOE). Electrospinning process parameters such as solution concentration, DMF content in CF/DMF solvent mixture, and applied voltage are varied at three different levels (L 9 ). Analysis of variance (ANOVA) indicated DMF content to be the major influencing factor on FD and SD of EMs with ∼95% confidence. Regression model indicated ∼88% accuracy in predicting the FD of the copolymer-based EMs. The physico-mechanical properties of the optimized EMs are evaluated vis-à-vis the influence of FD and SD on the mechanical properties. Atomic force microscopy revealed solvent evaporation induced radial inconsistencies, desirable in terms of nanoscale surface roughness, which is higher for Co-SD (∼600 nm) than in Co-FD (∼400 nm). The swelling and weight loss showed marked improvement in PCL-b-PLLA based EMs reiterating the possibility of their enhanced compatibility as biomedical materials.

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Influence of different β-nucleation agents on poly(l-lactic acid): structure, morphology, and dynamic mechanical behavior

Abstract: The WBG-II and TMB-5000 are both effective nucleating agents, which not only can enhance the crystallization rate, but also alter the packing structure of PLLA chain in the crystals.

Cited by 21 publications

References 48 publications

Development of Highly Crystalline Polylactic Acid with β-Crystalline Phase from the Induced Alignment of Electrospun Fibers

Development of Highly Crystalline Polylactic Acid with β-Crystalline Phase from the Induced Alignment of Electrospun Fibers

New Biodegradable Poly(l-lactide)-Block-Poly(propylene adipate) Copolymer Microparticles for Long-Acting Injectables of Naltrexone Drug

Synthesis, Optimal Fabrication, and Physico‐Mechanical Property Evaluation of PCL‐b‐PLLA Diblock Copolymer‐Based Nanoscale Roughness Textured Electrospun Mats

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