Comparison study of hydrolytic degradation behaviors between α′- and α-poly( l -lactide)

Zhang, Nan; Yu, Xu; Duan, Jin; Yang, Jing‐hui; Huang, Ting; Qi, Xiao-dong; Wang, Yong

doi:10.1016/j.polymdegradstab.2017.12.014

Cited by 36 publications

(18 citation statements)

References 51 publications

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“…N. Zangg et. all demonstrated different hydrolytic degradation behaviour of α′- and α-PLLA 22 . Thus it is quite important to control the polymorphism for optimizing the properties of PLLA.…”

Section: Resultsmentioning

confidence: 93%

Diverse nature of femtosecond laser ablation of poly(L-lactide) and the influence of filamentation on the polymer crystallization behaviour

Stępak

Gazińska

Nejbauer

et al. 2019

Sci Rep

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Over the past few years we have witnessed growing interest in ultrafast laser micromachining of bioresorbable polymers for fabrication of medical implants and surface modification. In this paper we show that surface structuring of poly(L-lactide) with 300 fs laser pulses at 515 and 1030 nm wavelength leads to formation of defects inside the polymer as a result of laser beam filamentation. Filament-induced channels have diameter around 1 μm and length of hundreds of micrometers. SEM images of microchannels cross-sections are presented. The influence of wavelength and pulse spacing on bulk modification extent was investigated and parameters limiting filamentation were determined. We show that filamentation can be used for controlling properties of PLLA. The presence of filament-induced modifications such as empty microchannels and pressure wave-induced stress lead to increased ability of polymer to crystallize at lower temperature. Crystallization behaviour and crystal morphology after laser treatment was investigated in details using different analytical techniques such as WAXD, DSC and FTIR/ATR. Hydrolytic degradation experiment was performed. Presented method can be applied for controllable, spatially distributed modification of polymer crystallinity, crystalline phase structure and hydrolytic degradation profile.

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Section: Resultsmentioning

confidence: 93%

Diverse nature of femtosecond laser ablation of poly(L-lactide) and the influence of filamentation on the polymer crystallization behaviour

Stępak

Gazińska

Nejbauer

et al. 2019

Sci Rep

View full text Add to dashboard Cite

show abstract

“…This finding is important for the application of composites in regenerative medicine as bone scaffolds. The crystal form of PLLA significantly affects the mechanical properties and exhibits different hydrolytic degradation behavior [ 42 , 43 , 44 ]. For PLLGA, which has lower crystallization ability than PLLA, nucleation of melt crystallization was achieved only by HAP modified with PEG2100, whereas cold crystallization was enhanced by HAP modified with PEG2100 and PEG600.…”

Section: Discussionmentioning

confidence: 99%

Influence of Hydroxyapatite Surface Functionalization on Thermal and Biological Properties of Poly(l-Lactide)- and Poly(l-Lactide-co-Glycolide)-Based Composites

Gazińska

Krokos

Kobielarz

et al. 2020

IJMS

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Novel biocomposites of poly(L-lactide) (PLLA) and poly(l-lactide-co-glycolide) (PLLGA) with 10 wt.% of surface-modified hydroxyapatite particles, designed for applications in bone tissue engineering, are presented in this paper. The surface of hydroxyapatite (HAP) was modified with polyethylene glycol by using l-lysine as a linker molecule. The modification strategy fulfilled two important goals: improvement of the adhesion between the HAP surface and PLLA and PLLGA matrices, and enhancement of the osteological bioactivity of the composites. The surface modifications of HAP were confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), TGA, and elemental composition analysis. The influence of hydroxyapatite surface functionalization on the thermal and in vitro biological properties of PLLA- and PLLGA-based composites was investigated. Due to HAP modification with polyethylene glycol, the glass transition temperature of PLLA was reduced by about 24.5 °C, and melt and cold crystallization abilities were significantly improved. These achievements were scored based on respective shifting of onset of melt and cold crystallization temperatures and 1.6 times higher melt crystallization enthalpy compared with neat PLLA. The results showed that the surface-modified HAP particles were multifunctional and can act as nucleating agents, plasticizers, and bioactive moieties. Moreover, due to the presented surface modification of HAP, the crystallinity degree of PLLA and PLLGA and the polymorphic form of PLLA, the most important factors affecting mechanical properties and degradation behaviors, can be controlled.

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“…One potential criticism of the test method that it was conducted in a water bath given that it is known that hydrolysis and water absorption of PLLA can have a major effect on the mechanical properties [49][50][51][52]. However it should be noted that the timescale of the experiment is orders of magnitude smaller than the timescale for hydrolysis to have an influence [53][54][55][56][57]. To verify this, additional experiments have been performed where PLLA tubing was uniaxially stretched after heating in a wet environment for 8 min (similar to the timescale of the experiments in this paper) and after heating in a dry environment with no significant difference observed [58].…”

Section: Discussionmentioning

confidence: 99%

Experimental characterisation on the behaviour of PLLA for stretch blowing moulding of bioresorbable vascular scaffolds

et al. 2020

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Processing tubes from poly (l-lactic acid) (PLLA) by stretch blow moulding (SBM) is used in the manufacture of bioresorbable vascular scaffolds (BVS) to improve their mechanical performance. To better understand this processing technique, a novel experimental setup by free stretch blow inside a water bath was developed to visualise the tube forming process and analyse the deformation behaviour. PLLA tubes were heated, stretched and blown with no mould present inside a temperature-controlled water bath whilst recording the processing parameters (axial force, inflation pressure). The onset of pressure activation relative to the axial stretch was controlled deliberately to produce a simultaneous (SIM) or sequential (SEQ) mode of deformation. Realtime images of the tube during forming were captured using high speed cameras and the surface strain of the patterned tube was extracted using digital image correlation (DIC). The deformation characteristics of PLLA tubes in SBM was quantified by analysis of shape evolution, strain history and stress-strain relationship.

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Comparison study of hydrolytic degradation behaviors between α′- and α-poly( l -lactide)

Cited by 36 publications

References 51 publications

Diverse nature of femtosecond laser ablation of poly(L-lactide) and the influence of filamentation on the polymer crystallization behaviour

Diverse nature of femtosecond laser ablation of poly(L-lactide) and the influence of filamentation on the polymer crystallization behaviour

Influence of Hydroxyapatite Surface Functionalization on Thermal and Biological Properties of Poly(l-Lactide)- and Poly(l-Lactide-co-Glycolide)-Based Composites

Experimental characterisation on the behaviour of PLLA for stretch blowing moulding of bioresorbable vascular scaffolds

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