In the course of miniaturization down to the nanometer scale, much remains unknown concerning how and to what extent the properties of materials are changed. To learn more about the dynamics of condensed isolated polymer chains, we used broadband dielectric spectroscopy and a capacitor with nanostructured electrodes separated by 35 nanometers. We measured the dynamic glass transition of poly(2-vinylpyridine) and found it to be bulk-like; only segments closer than 0.5 nanometer to the substrate were weakly slowed. Our approach paves the way for numerous experiments on the dynamics of isolated molecules.

https://science.sciencemag.org/content/sci/341/6152/1371.full.pdf

Glassy dynamics in condensed isolated polymer chains.

Spectroscopic vis-ellipsometry and broadband dielectric spectroscopy (BDS) are combined to study the glassy dynamics of thin (≥10 nm) layers of atactic poly(methyl methacrylate) (PMMA) annealed and measured under identical conditions. In order to unravel a possible effect of the underlying substrate, the interfacial interactions are systematically modified ranging from strong attractive interactions for covalently bonded PMMA brushes with high grafting density and for native silicon oxide (Si/SiOx) to weak and strong repulsive interactions as realized by Au-coated and HMDS-treated Si/SiOx surfaces, respectively. Down to the thinnest analyzed PMMA layers and independently from the applied substrate, both methods deliver—within the experimental accuracy (±1 K for BDS and ±2 K for ellipsometry)—a coinciding result. The glassy dynamics are not altered due to the one-dimensional confinement in these thin polymer layers. The results are discussed with respect to the highly controversial literature and the impac...

/pdf/glassy-dynamics-and-glass-transition-in-thin-polymer-layers-1o22ilpaca.pdf

Glassy Dynamics and Glass Transition in Thin Polymer Layers of PMMA Deposited on Different Substrates

Polar topological texture has become an emerging research field for exotic phenomena and potential applications in reconfigurable electronic devices. We report toroidal topological texture self-organized in a ferroelectric polymer, poly(vinylidene fluoride-ran-trifluoroethylene) [P(VDF-TrFE)], that exhibits concentric topology with anticoupled chiral domains. The interplay among the elastic, electric, and gradient energies results in continuous rotation and toroidal assembly of the polarization perpendicular to polymer chains, whereas relaxor behavior is induced along polymer chains. Such toroidal polar topology gives rise to periodic absorption of polarized far-infrared (FIR) waves, enabling the manipulation of the terahertz wave on a mesoscopic scale. Our observations should inform design principles for flexible ferroic materials toward complex topologies and provide opportunities for multistimuli conversions in flexible electronics.

Toroidal polar topology in strained ferroelectric polymer.

Supercooled Liquids and Glasses by Dielectric Relaxation Spectroscopy

Segmental and chain dynamics in nanometric (7–400 nm) layers of poly (cis-1,4-isoprene) (PI) are analyzed by Broadband Dielectric Spectroscopy (BDS) and temperature-modulated AC calorimetry. While for the segmental mode, taking place at the length scale of 2–3 polymer segments and corresponding to the dynamic glass transition, no dependence on the layer thickness and molecular weight is found, the normal mode, reflecting fluctuations of the end-to-end vector of the chain, shows pronounced effects: (i) it strongly varies in its relaxation strength with the layer thickness; (ii) for polymers having a molecular weight Mw comparable to M*, the critical molecular weight marking the onset of reptation dynamics, the mean spectral position does not change with the thickness, (iii) in contrast, polymers with Mw > M* are found to be severely influenced in their relaxation strength and the mean spectral position of the normal mode relaxation, and (iv) it is proven that the concentration of the polymer solution out of which the layers are prepared by spincoating has a hitherto unrecognized impact on the chain dynamics in (one-dimensional) nanometric confinement. These results prove that the dynamic glass transition in thin layers of PI is not influenced by nanometric confinement, while the chain dynamics are altered in a manifold of ways due to interactions with the surface of the underlying substrate.

Segmental and chain dynamics in nanometric layers of poly(cis-1,4-isoprene) as studied by broadband dielectric spectroscopy and temperature-modulated calorimetry

By employing silica nanostructures as spacers, an experimental approach is developed to enable one broadband dielectric measurements on the molecular dynamics taking place in the immediate (nanometric) vicinity of solid interfaces. This development renders to broadband dielectric spectroscopy—traditionally a bulk technique—the character of an interfacial method.

Broadband dielectric studies on the interfacial dynamics enabled by use of nanostructured electrodes

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

A. Serghei

Author Tools

Chat about Author

Papers

Broadband dielectric studies on the interfacial dynamics enabled by use of nanostructured electrodes