Structural recovery of a single polystyrene thin film using nanocalorimetry to extend the aging time and temperature range

Koh, Yung P.; Grassia, Luigi; Simon, Sindee L.

doi:10.1016/j.tca.2014.08.025

Cited by 62 publications

(98 citation statements)

References 49 publications

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“…However, the sample preparation is time consuming since it requires the stacking of several hundred layers of ultrathin film in order to meet the mass requirement . With the new developments of the nanocalorimetry, including flash DSC and AC‐chip calorimetry (We note here that the modulated DSC and the AC‐chip calorimetry are considered as dynamic measurements of T g ), which has the mass requirement of nanogram, measuring the T g of sub‐100 nm a single layer of polymer ultrathin film with DSC becomes possible and has drawn increasing attention …”

Section: Experimental Techniques To Measure Tgmentioning

confidence: 99%

Glass Transition Phenomenon for Conjugated Polymers

Qian

Cao

Galuska

et al. 2019

Macro Chemistry & Physics

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Conjugated polymers are emerging as promising building blocks for a broad range of modern applications including skin‐like electronics, wearable optoelectronics, and sensory technologies. In the past three decades, the optical and electronic properties of conjugated polymers have been extensively studied, while their thermomechanical properties, especially the glass transition phenomenon which fundamentally represents the polymer chain dynamics, have received much less attention. Currently, there is a lack of design rules that underpin the glass transition temperature of these semirigid conjugated polymers, putting a constraint on the rational polymer design for flexible stretchable devices and stable polymer glass that is needed for the devices’ long‐term morphology stability. In this review article, the glass transition phenomenon for polymers, glass transition theories, and characterization techniques are first discussed. Then previous studies on the glass transition phenomenon of conjugated polymers are reviewed and a few empirical design rules are proposed to fine‐tune the glass transition temperature for conjugated polymers. The review paper is finished with perspectives on future directions on studying the glass transition phenomena of conjugated polymers. The goal of this perspective is to draw attention to challenges and opportunities of controlling, predicting, and designing polymeric semiconductors, specifically to accommodate their end use.

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Section: Experimental Techniques To Measure Tgmentioning

confidence: 99%

Glass Transition Phenomenon for Conjugated Polymers

Qian

Cao

Galuska

et al. 2019

Macro Chemistry & Physics

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“…From a fundamental perspective, controlled quench conditions associated with glass formation, which impacts the aging characteristics, is commonly achieved by heating the film above its T g to erase the temperature history and then quenching to the desired aging temperature. Practically, this annealing of the film prior to service is not always viable, such as in the manufacture of membranes or when the polymer is heat sensitive.…”

Section: Introductionmentioning

confidence: 99%

Thickness dependence of structural relaxation in spin‐cast polynorbornene films with high glass transition temperatures (>613 K)

Lewis

Vogt

2017

J Polym Sci B Polym Phys

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The isothermal structural relaxation (densification) of a family of glassy polynorbornene films with high glass transition temperatures (T g > 613 K) is assessed via spectroscopic ellipsometry. Three polymers were examined: poly(butylnorbornene) (BuNB), poly(hydroxyhexafluoroisopropyl norbornene) (HFANB), and their random copolymer, BuNB-r-HFANB. The effective aging rate, b(T), of thick ($1.2 lm) spun cast films of BuNB-r-HFANB is approximately 10 23 over a wide temperature window (0.49 < T/T g < 0.68). At higher temperatures, these polymers undergo reactions that more dramatically decrease the film thickness, which prohibits erasing the process history by annealing above T g . The aging rate for thick BuNB-r-HFANB films is independent of the casting solvent, which infers that rapid aging is not associated with residual solvent. b (at 373 K) decreases for films thinner than $500 nm. However, the isothermal structural relaxation of thin films of BuNB-r-HFANB exhibits nonmonotonic temporal evolution in thickness for films thinner than 115 nm film. The thickness after 18 h of aging at 373 K can be greater than the initial thickness. The rapid aging of these polynorbornene films is attributed to the unusual rapid local dynamics of this class of polymers and demonstrates the potential for unexpected structural relaxations in membranes and thin films of high-T g polymers that could impact their performance.

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“…Up to date considerable efforts have been made to understand the physical aging mechanism of neat polymers such as poly (methyl methacrylate) (PMMA), poly(vinyl acetate) (PVAc), polylactide (PLA), or poly (ethylene terephthalate) (PET) . In this framework, some authors have found that the inclusion of nano‐reinforcements into polymeric materials reduces the physical aging of bulk nanocomposites .…”

Section: Introductionmentioning

confidence: 99%

Physical aging and mechanical performance of poly(l‐lactide)/ZnO nanocomposites

Lizundia

Pérez‐Álvarez

Sáenz-Pérez

et al. 2016

J of Applied Polymer Sci

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In this work nanocomposites based on poly (l‐lactide) (PLLA) and zinc oxide (ZnO) nanoparticles with a concentration up to 5 wt % have been prepared by solvent‐precipitation followed by compression moulding at 200 °C. Structural evolution of nanocomposites as a function of time and nanoparticle concentration has been monitored by differential scanning calorimetry (DSC). Results reveal a marked reduction of the enthalpy relaxation rate βH from 3.273 J/g for neat polymer to 0.912 J/g for its 0.25 wt % reinforced counterpart, revealing slower aging dynamics induced by zinc oxide. It is shown by field emission scanning electron microscopy (FE‐SEM) that concentrations larger than 1 wt % yield nanoparticle agglomeration. These large aggregates decrease the amount of nanoparticle surfaces exposed to PLLA chains, notably reducing the efficiency of ZnO nanoparticles to delay the physical aging of its hosting matrix. Mechanical tests show an increased stiffness upon ZnO loading as denoted by the increase in modulus from 2310 MPa to 2780 MPa for the 1 wt % nanocomposite. Obtained findings through this work lead the way for the development of nanocomposites based on renewable polymers and natural fillers to be used in packaging applications, where the use of nonbiodegradable materials for short‐term applications is extended. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43619.

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Structural recovery of a single polystyrene thin film using nanocalorimetry to extend the aging time and temperature range

Cited by 62 publications

References 49 publications

Glass Transition Phenomenon for Conjugated Polymers

Glass Transition Phenomenon for Conjugated Polymers

Thickness dependence of structural relaxation in spin‐cast polynorbornene films with high glass transition temperatures (>613 K)

Physical aging and mechanical performance of poly(l‐lactide)/ZnO nanocomposites

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