Highlight of primary and secondary relaxations in amorphous stereocomplex polylactides

Varol, Nagihan; Monnier, Xavier; Delbreilh, Laurent; Saiter, Allisson; Fatyeyeva, Kateryna; Dargent, Éric

doi:10.3144/expresspolymlett.2020.5

Cited by 13 publications

(7 citation statements)

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“…The ionic conductivity is inversely proportional to the relaxation time, thus, the decrease in the relaxation time causes an increase in the ionic conductivity. 32 Interestingly, the relaxation time of the PEO/K2PtCl6 in T≲ Tg follows the Arrhenius-like behavior (as seen in Figure 3) similar to that for T g of the pure PEO as prepared by the solution-casting method prepared in to our previous works. 23,33 This behavior is the typical behavior of β-relaxation processes in glass formers polymers 34 such as PEO.…”

Section: Relaxation Time (τ)supporting

confidence: 79%

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Studies of composite films of polyethylene oxide doped with potassium hexachloroplatinate

Al-Akhras

Alzoubi

Ababneh

et al. 2020

J of Applied Polymer Sci

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The permittivity and conductivity relaxation processes of polyethylene oxide (PEO) composite along with potassium hexachloroplatinate (K 2 PtCl 6) electrolytes additive forming PEO/K 2 PtCl 6 complex composite have been investigated. The complex composite has been used as a model for dry-polymer electrolytes (PEs) due to the fact that, the anion is large enough for mimicking the immobilized anion in real dry-polymer electrolytes. Stand-free composite films with 0%, 1%, 3%, and 5% concentrations of K 2 PtCl 6 have been studied using broadband dielectric spectroscopy in the temperatures range from 150 K until 345 K. The microstructural dynamics revealed the α-, β-, and σ-relaxations and their salient spectral characteristics at various concentrations of K 2 PtCl 6 in PEO. The experimental ε" master curves were fitted to HN function for one and/or two relaxation peaks with and without the electrical conductivity contribution in order to investigate the relaxation time (τ), dielectric strengths (Δε), modulus formalism (M") and the electrical conductivitie (σ). The translational and reorientational degrees of freedom of PEO/K 2 PtCl 6 complex composites are responsible for the relaxation behavior which is predicted to be correlated to the relaxation behavior of the polymer electrolyte below and above the glass transition temperature (T g). The relaxation time (τ) deduced from β-relaxation follows Arrhenius-like behavior while that deduced from α-relaxation process follows Vogel-Tamman-Fulcher (VTF) behavior.

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Section: Relaxation Time (τ)supporting

confidence: 79%

“…The decrease in the relaxation time is attributed to the increase in the ion‐hoping rate from one coordinating site to the other site. The ionic conductivity is inversely proportional to the relaxation time, thus, the decrease in the relaxation time causes an increase in the ionic conductivity 32 …”

Section: Resultsmentioning

confidence: 99%

Studies of composite films of polyethylene oxide doped with potassium hexachloroplatinate

Al-Akhras

Alzoubi

Ababneh

et al. 2020

J of Applied Polymer Sci

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“…Hence, the activation parameters could be obtained exclusively for the PLLA/10 W/APE sample. The activation energy E a of local motions of polymer chains in the system was equal to 58.2 kJ/mol, which is 1.5 times greater in comparison with pure PLLA [ 86 , 87 ]. This proves the restriction of molecular dynamics in the case of coated wood addition.…”

Section: Resultsmentioning

confidence: 99%

Poly(l-Lactic Acid)/Pine Wood Bio-Based Composites

et al. 2020

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Bio-based composites made of poly(l-lactic acid) (PLLA) and pine wood were prepared by melt extrusion. The composites were compatibilized by impregnation of wood with γ-aminopropyltriethoxysilane (APE). Comparison with non-compatibilized formulation revealed that APE is an efficient compatibilizer for PLLA/wood composites. Pine wood particles dispersed within PLLA act as nucleating agents able to start the growth of PLLA crystals, resulting in a faster crystallization rate and increased crystal fraction. Moreover, the composites have a slightly lower thermal stability compared to PLLA, proportional to filler content, due to the lower thermal stability of wood. Molecular dynamics was investigated using the solid-state 1H NMR technique, which revealed restrictions in the mobility of polymer chains upon the addition of wood, as well as enhanced interfacial adhesion between the filler and matrix in the composites compatibilized with APE. The enhanced interfacial adhesion in silane-treated composites was also proved by scanning electron microscopy and resulted in slightly improved deformability and impact resistance of the composites.

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“…In addition, PLA micelles crystallized in stereocomplex phase were also achieved from PEG-PLLA-PDLA stereoblock copolymers by the nanoprecipitation method, which exhibited a slower drug release rate than the amorphous and isotactic counterpart [16]. However, the copolymerization of PLA with PGA or PEG usually deters the crystallization of the nanoparticles, limiting the physicochemical properties of the PLA-derivatives to the characteristic features of the amorphous phase [15] that neutralize the PLA chirality effect on the molecular mobility and the relaxation process [17]. Alternative processing methods are urged to favor the hydrophilicity of the PLA-based material whilst retaining the tunability of the physicochemical properties for the nanostructured PLA derivatives.…”

Section: Introductionmentioning

confidence: 99%

Multifunctional PLA/Gelatin Bionanocomposites for Tailored Drug Delivery Systems

Moya-Lopez

Juan²,

Donizeti

et al. 2022

Pharmaceutics

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A series of bionanocomposites composed of shark gelatin hydrogels and PLA nanoparticles featuring different nanostructures were designed to generate multifunctional drug delivery systems with tailored release rates required for personalized treatment approaches. The global conception of the systems was considered from the desired customization of the drug release while featuring the viscoelastic properties needed for their ease of storage and posterior local administration as well as their biocompatibility and cell growth capability for the successful administration at the biomolecular level. The hydrogel matrix offers the support to develop a direct thermal method to convert the typical kinetic trapped nanostructures afforded by the formulation method whilst avoiding the detrimental nanoparticle agglomeration that diminishes their therapeutic effect. The nanoparticles generated were successfully formulated with two different antitumoral compounds (doxorubicin and dasatinib) possessing different structures to prove the loading versatility of the drug delivery system. The bionanocomposites were characterized by several techniques (SEM, DLS, RAMAN, DSC, SAXS/WAXS and rheology) as well as their reversible sol–gel transition upon thermal treatment that occurs during the drug delivery system preparation and the thermal annealing step. In addition, the local applicability of the drug delivery system was assessed by the so-called “syringe test” to validate both the storage capability and its flow properties at simulated physiological conditions. Finally, the drug release profiles of the doxorubicin from both the PLA nanoparticles or the bionanocomposites were analyzed and correlated to the nanostructure of the drug delivery system.

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Highlight of primary and secondary relaxations in amorphous stereocomplex polylactides

Cited by 13 publications

References 0 publications

Studies of composite films of polyethylene oxide doped with potassium hexachloroplatinate

Studies of composite films of polyethylene oxide doped with potassium hexachloroplatinate

Poly(l-Lactic Acid)/Pine Wood Bio-Based Composites

Multifunctional PLA/Gelatin Bionanocomposites for Tailored Drug Delivery Systems

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