Competition between nucleation and confinement in the crystallization of poly(ethylene glycol)/ large aspect ratio hectorite nanocomposites

Habel, Christoph; Maiz, Jon; Olmedo‐Martínez, Jorge L.; López, José Antonio Fernández; Breu, Josef; Müller, Alejandro J.

doi:10.1016/j.polymer.2020.122734

Cited by 21 publications

(24 citation statements)

References 46 publications

(62 reference statements)

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“…Previous studies have reported intercalated phases of layered silicates with PEG volume contents of 46 vol % 34 − 36 , 43 , 44 and 30 vol % 36 corresponding to periodicities of 1.8 and 1.4 nm, respectively. The present observed periodicities (1.77 and 1.38 nm for Hec/2PEG and Hec/1PEG, respectively; Figure 2 , bottom) agree well with the published values.…”

Section: Resultsmentioning

confidence: 98%

Nanoscale-Structured Hybrid Bragg Stacks with Orientation- and Composition-Dependent Mechanical and Thermal Transport Properties: Implications for Nacre Mimetics and Heat Management Applications

Dörres

Bartkiewicz

Herrmann

et al. 2022

ACS Appl. Nano Mater.

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Layered nanomaterials fascinate researchers for their mechanical, barrier, optical, and transport properties. Nacre is a biological example thereof, combining excellent mechanical properties by aligned submicron inorganic platelets and nanoscale proteinic interlayers. Mimicking nacre with advanced nanosheets requires ultraconfined organic layers aimed at nacre-like high reinforcement fractions. We describe inorganic/polymer hybrid Bragg stacks with one or two fluorohectorite clay layers alternating with one or two poly(ethylene glycol) layers. As indicated by X-ray diffraction, perfect one-dimensional crystallinity allows for homogeneous single-phase materials with up to a 84% clay volume fraction. Brillouin light spectroscopy allows the exploration of ultimate mechanical moduli without disturbance by flaws, suggesting an unprecedentedly high Young’s modulus of 162 GPa along the aligned clays, indicating almost ideal reinforcement under these conditions. Importantly, low heat conductivity is observed across films, κ ⊥ = 0.11–0.15 W m –1 K –1 , with a high anisotropy of κ ∥ /κ ⊥ = 28–33. The macroscopic mechanical properties show ductile-to-brittle change with an increase in the clay volume fraction from 54% to 70%. Conceptually, this work reveals the ultimate elastic and thermal properties of aligned layered clay nanocomposites in flaw-tolerant conditions.

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Section: Resultsmentioning

confidence: 98%

Nanoscale-Structured Hybrid Bragg Stacks with Orientation- and Composition-Dependent Mechanical and Thermal Transport Properties: Implications for Nacre Mimetics and Heat Management Applications

Dörres

Bartkiewicz

Herrmann

et al. 2022

ACS Appl. Nano Mater.

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“…The overall isothermal crystallization behavior was probed by the DSC measurements in which both primary nucleation and crystal growth are considered [ 56 , 57 ]. Avrami equation was employed to understand the primary crystallization process.…”

Section: Resultsmentioning

confidence: 99%

Isothermal Crystallization Kinetics of Poly(ethylene oxide)/Poly(ethylene glycol)-g-silica Nanocomposites

Wen

et al. 2021

Polymers

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In this work, the crystallization kinetics of poly(ethylene oxide) (PEO) matrix included with poly(ethylene glycol) (PEG) grafted silica (PEG-g-SiO2) nanoparticles and bare SiO2 were systematically investigated by differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM) method. PEG-g-SiO2 can significantly increase the crystallinity and crystallization temperature of PEO matrix under the non-isothermal crystallization process. Pronounced effects of PEG-g-SiO2 on the crystalline morphology and crystallization rate of PEO were further characterized by employing spherulitic morphological observation and isothermal crystallization kinetics analysis. In contrast to the bare SiO2, PEG-g-SiO2 can be well dispersed in PEO matrix at low P/N (P: Molecular weight of matrix chains, N: Molecular weight of grafted chains), which is a key factor to enhance the primary nucleation rate. In particular, we found that the addition of PEG-g-SiO2 slows the spherulitic growth fronts compared to the neat PEO. It is speculated that the interfacial structure of the grafted PEG plays a key role in the formation of nuclei sites, thus ultimately determines the crystallization behavior of PEO PNCs and enhances the overall crystallization rate of the PEO nanocomposites.

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“…This is even more critical in the case of layered additives, in which the interactions not only affect the dispersion of the additive within the polymer matrix, but they define the final nanohybrid structure as well. In such cases, three different structures can be obtained depending on the interactions [ 33 , 34 ]: (i) the phase separated, when the interactions between the chains and the fillers are unfavorable, which results in each component residing in its own phase; (ii) the intercalated one [ 17 , 28 , 29 , 35 , 36 , 37 ], where the polymer can diffuse between the layers of the additive, creating a structure of alternating soft–hard components, each one of nm-thickness, and (iii) the exfoliated one [ 38 , 39 , 40 , 41 , 42 , 43 ], where the favorable interactions lead to the destruction of the layered structure of the inorganic material and to the dispersion of individual platelets within the polymer. Both intercalated and exfoliated structures offer certain advantages: the former shows enhanced mechanical properties, while for hybrids with low polymer content, it offers the ability to investigate polymer structure, dynamics and properties under severe confinement, whereas the latter provides optimized properties due to the percolated network formed from the dispersion of the additive platelets [ 44 , 45 ].…”

Section: Introductionmentioning

confidence: 99%

Static and Dynamic Behavior of Polymer/Graphite Oxide Nanocomposites before and after Thermal Reduction

et al. 2021

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Nanocomposites of hyperbranched polymers with graphitic materials are investigated with respect to their structure and thermal properties as well as the dynamics of the polymer probing the effect of the different intercalated or exfoliated structure. Three generations of hyperbranched polyester polyols are mixed with graphite oxide (GO) and the favorable interactions between the polymers and the solid surfaces lead to intercalated structure. The thermal transitions of the confined chains are suppressed, whereas their dynamics show similarities and differences with the dynamics of the neat polymers. The three relaxation processes observed for the neat polymers are observed in the nanohybrids as well, but with different temperature dependencies. Thermal reduction of the graphite oxide in the presence of the polymer to produce reduced graphite oxide (rGO) reveals an increase in the reduction temperature, which is accompanied by decreased thermal stability of the polymer. The de-oxygenation of the graphite oxide leads to the destruction of the intercalated structure and to the dispersion of the rGO layers within the polymeric matrix because of the modification of the interactions between the polymer chains and the surfaces. A significant increase in the conductivity of the resulting nanocomposites, in comparison to both the polymers and the intercalated nanohybrids, indicates the formation of a percolated rGO network.

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Competition between nucleation and confinement in the crystallization of poly(ethylene glycol)/ large aspect ratio hectorite nanocomposites

Cited by 21 publications

References 46 publications

Nanoscale-Structured Hybrid Bragg Stacks with Orientation- and Composition-Dependent Mechanical and Thermal Transport Properties: Implications for Nacre Mimetics and Heat Management Applications

Nanoscale-Structured Hybrid Bragg Stacks with Orientation- and Composition-Dependent Mechanical and Thermal Transport Properties: Implications for Nacre Mimetics and Heat Management Applications

Isothermal Crystallization Kinetics of Poly(ethylene oxide)/Poly(ethylene glycol)-g-silica Nanocomposites

Static and Dynamic Behavior of Polymer/Graphite Oxide Nanocomposites before and after Thermal Reduction

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