Crystallization Behavior of Pebax–Graphene Composite Matrix with and without Supercritical Carbon Dioxide Assisted Polymer Processing Technique

Karode, Nireeksha; Poudel, Anup; Fitzhenry, Laurence; Matthews, Siobhán; Redington, Wynette; Walsh, Philip R.; Coffey, Austin

doi:10.1021/acs.cgd.8b00277

Cited by 10 publications

(6 citation statements)

References 53 publications

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“…Conversely, solvent-cast 1.5% w/v BNNT nanocomposite films were observed to contain BNNT agglomerations as (Figures 1A–D). However, use of further dispersal techniques as described previously could be used for better dispersion of BNNT at higher percentage in the polymer matrix and will be investigated in a follow-up study (Karode et al, 2018; Poudel et al, 2019). 1 wt.% BNNT nanocomposite films were subsequently selected for the focus of this study as the alteration of crystalline behavior of polymers upon the addition of a nanoscale filler is more pronounced when the fillers wt.% is sufficiently lower than the threshold concentration at which agglomeration occurs (Karode et al, 2018).…”

Section: Resultsmentioning

confidence: 99%

“…The ferroelectric, piezoelectric and pyroelectric properties of these polymers, depends on the polymorphic crystalline phases present within their semi-crystalline polymer matrix (Boccaccio et al, 2002; Gregorio, 2006; Lutkenhaus et al, 2010), which can be modulated through various physicomechanical processing techniques (Karode et al, 2018). In particular, Poly(vinylidene fluoride) [PVDF], a semi-crystalline fluorinated polymer has been studied extensively as a ferroelectric material, demonstrating five different crystal phases (α-phase, β-phase, α]-phase γ-phase, ε-phase, and δ-phase) (Cui et al, 2015).…”

Section: Background and Introductionmentioning

confidence: 99%

“…It has been reported however, that annealing of PVDF-TrFE between the Curie and melt temperatures, further increases the β-phase crystallinity, due to enhanced molecular movement with increased temperature (Zeng et al, 2009; Lau et al, 2013). The addition of micro and nanoscale fillers has also been shown to alter the piezoelectric, thermal and mechanical behavior of PVDF with the formation of additional phases between the polymer and the filler interface (Karode et al, 2018; Mayeen et al, 2018). However, the dynamics of polymorphism mechanisms in PVDF-TrFE and its composites with the addition of different nano/micro fillers are still not well-understood, restricting the use of piezoelectric composites as smart electromechanical materials.…”

Section: Background and Introductionmentioning

confidence: 99%

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Boron Nitride Nanotube Addition Enhances the Crystallinity and Cytocompatibility of PVDF-TrFE

et al. 2019

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Analysis of the cellular response to piezoelectric materials has been driven by the discovery that many tissue components exhibit piezoelectric behavior ex vivo . In particular, polyvinylidene fluoride and the trifluoroethylene co-polymer (PVDF-TrFE) have been identified as promising piezo and ferroelectric materials with applications in energy harvesting and biosensor devices. Critically, the modulation of the structural and crystalline properties of PVDF-TrFE through annealing processes and the addition of particulate or fibrous fillers has been shown to modulate significantly the materials electromechanical properties. In this study, a PVDF-TrFE/boron-nitride nanotube composite was evaluated by modulated differential scanning calorimetry to assess the effects of boron nitride nanotube addition and thermal annealing on the composite structure and crystal behavior. An increased beta crystal formation [f(β) = 0.71] was observed following PVDF-TrFE annealing at the first crystallization temperature of 120°C. In addition, the inclusion of boron nitride nanotubes significantly increased the crystal formation behavior [f(β) = 0.76] and the mechanical properties of the material. Finally, it was observed that BNNT incorporation enhance the adherence and proliferation of human tenocyte cells in vitro .

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Section: Resultsmentioning

confidence: 99%

Section: Background and Introductionmentioning

confidence: 99%

Section: Background and Introductionmentioning

confidence: 99%

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Boron Nitride Nanotube Addition Enhances the Crystallinity and Cytocompatibility of PVDF-TrFE

et al. 2019

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“…However, when the ratio of EDL:Ag was decreased to 10:1, the storage modulus as well as gelation frequency was also observed to decrease. This phenomenon was attributed to the agglomeration of AgNWs after some threshold concentration as described previously [ 38 ]. The lowest critical strain rate was observed in the composite formulation with an EDL to Ag ratio of 10:1.…”

Section: Discussionmentioning

confidence: 63%

Analysis of a poly(ε-decalactone)/silver nanowire composite as an electrically conducting neural interface biomaterial

Krukiewicz

Fernández²,

Skorupa

et al. 2019

BMC biomed eng

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Background Advancement in polymer technologies, facilitated predominantly through chemical engineering approaches or through the identification and utilization of novel renewable resources, has been a steady focus of biomaterials research for the past 50 years. Aliphatic polyesters have been exploited in numerous biomedical applications including the formulation of soft-tissue sutures, bone fixation devices, cardiovascular stents etc. Biomimetic ‘soft’ polymer formulations are of interest in the design of biological interfaces and specifically, in the development of implantable neuroelectrode systems intended to interface with neural tissues. Critically, soft polymer formulations have been shown to address the challenges associated with the disregulation of mechanotransductive processes and micro-motion induced inflammation at the electrode/tissue interface. In this study, a polyester-based poly(ε-decalactone)/silver nanowire (EDL:Ag) composite was investigated as a novel electrically active biomaterial with neural applications. Neural interfaces were formulated through spin coating of a polymer/nanowire formulation onto the surface of a Pt electrode to form a biocompatible EDL matrix supported by a percolated network of silver nanowires. As-formed EDL:Ag composites were characterized by means of infrared spectroscopy, scanning electron microscopy and electrochemical methods, with their cytocompatibility assessed using primary cultures of a mixed neural population obtained from the ventral mesencephalon of Sprague-Dawley rat embryos. Results Electrochemical characterization of various EDL:Ag composites indicated EDL:Ag 10:1 as the most favourable formulation, exhibiting high charge storage capacity (8.7 ± 1.0 mC/cm 2 ), charge injection capacity (84.3 ± 1.4 μC/cm 2 ) and low impedance at 1 kHz (194 ± 28 Ω), outperforming both pristine EDL and bare Pt electrodes. The in vitro biological evaluation showed that EDL:Ag supported significant neuron viability in culture and to promote neurite outgrowth, which had the average length of 2300 ± 6 μm following 14 days in culture, 60% longer than pristine EDL and 120% longer than bare Pt control substrates. Conclusions EDL:Ag nanocomposites are shown to serve as robust neural interface materials, possessing favourable electrochemical characteristics together with high neural cytocompatibility.

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“…This suggests the second stage of the phase transition requires more energy to reorganize into a new crystal structure, which likely proceeds via the nucleation and growth transition pathway. The Jeziorny model, derived on the basis of the nucleation growth mechanism, was thus used for kinetic data fitting (Jeziorny, 1978;Karode et al, 2018). The Jeziorny equation is given by…”

Section: Figurementioning

confidence: 99%

Distinct pathways of solid-to-solid phase transitions induced by defects: the case of DL-methionine

Shi

et al. 2021

IUCrJ

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Understanding of solid-to-solid phase transition mechanisms in polymorphic systems is of critical importance for rigorous control over polymorph purity in the pharmaceutical industry to achieve the desired bioavailability and efficacy of drugs. Ubiquitous defects in crystals may play an important role in the pathways of phase transitions. However, such effects remain poorly understood. Here, the effects of crystal defects on the solid-to-solid phase transformations between DL-methionine polymorphs α and β are investigated by means of experimental and computational approaches. Thermal analyses of polycrystalline powders show two endothermic peaks in the α-to-β phase transition (and two exothermic peaks for the reverse transition), in contrast with one thermal event observed for single crystals. Variable-temperature 1D and 2D Raman spectra, as well as powder X-ray diffraction patterns, reveal the appearance of two peaks that can attributed to a two-step phase transition, and the extent of the second-step phase transition increases with milling time (or defect density). Quantification of transition kinetics unveils a remarkably higher energy barrier in the second-step phase transition than in the first, proceeding by the cooperative molecular motion pathway. The good linear fitting on the kinetic data by the Jeziorny model suggests that the second-step transition follows the nucleation and growth mechanism. Molecular dynamics simulations were also conducted to understand the role of crystal defects in the solid-state phase transition by tracking the atomic distribution and hydrogen bond lifetime during the transition. It was found that the increasing defect density hinders the propagation of cooperative molecular motion, leading to a combined transition mechanism involving both cooperative motion and nucleation and growth. This study highlights the significant impact of crystal defects on solid-state phase transitions, and the two-step transition mechanism postulated may be universal given the ubiquitous presence of defects in crystalline materials.

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Crystallization Behavior of Pebax–Graphene Composite Matrix with and without Supercritical Carbon Dioxide Assisted Polymer Processing Technique

Cited by 10 publications

References 53 publications

Boron Nitride Nanotube Addition Enhances the Crystallinity and Cytocompatibility of PVDF-TrFE

Boron Nitride Nanotube Addition Enhances the Crystallinity and Cytocompatibility of PVDF-TrFE

Analysis of a poly(ε-decalactone)/silver nanowire composite as an electrically conducting neural interface biomaterial

Distinct pathways of solid-to-solid phase transitions induced by defects: the case of DL-methionine

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