scholarly journals Self-reporting visible light-induced polymer chain collapse

2019 ◽  
Vol 10 (33) ◽  
pp. 4513-4518 ◽  
Author(s):  
Janin T. Offenloch ◽  
Eva Blasco ◽  
Simon Bastian ◽  
Christopher Barner-Kowollik ◽  
Hatice Mutlu
Keyword(s):  
Visible Light ◽  
Polymer Chain ◽  
Polymer Chains ◽  
Diluted Solution

We introduce a facile photoinduced self-reporting crosslinking methodology for the compaction of polymer chains in highly diluted solution.

scholarly journals Collapse of a polymer chain in a melt of incompatible polymer chains

1981 ◽  
Vol 42 (8) ◽  
pp. 1145-1150 ◽  
Author(s):  
J.F. Joanny ◽  
F. Brochard
Keyword(s):  
Polymer Chain ◽  
Polymer Chains

scholarly journals Wavelength‐Selective Folding of Single Polymer Chains with Different Colors of Visible Light

2020 ◽  
Vol 41 (1) ◽  
pp. 2070001
Author(s):  
Hendrik Frisch ◽  
Daniel Kodura ◽  
Fabian R. Bloesser ◽  
Lukas Michalek ◽  
Christopher Barner‐Kowollik
Keyword(s):  
Visible Light ◽  
Polymer Chains

scholarly journals Wavelength‐Selective Folding of Single Polymer Chains with Different Colors of Visible Light

2019 ◽  
Vol 41 (1) ◽  
pp. 1900414 ◽  
Author(s):  
Hendrik Frisch ◽  
Daniel Kodura ◽  
Fabian R. Bloesser ◽  
Lukas Michalek ◽  
Christopher Barner‐Kowollik
Keyword(s):  
Visible Light ◽  
Polymer Chains

Electroelasticity of dielectric elastomers based on molecular chain statistics

2018 ◽  
Vol 24 (3) ◽  
pp. 862-873 ◽  
Author(s):  
Mikhail Itskov ◽  
Vu Ngoc Khiêm ◽  
Sugeng Waluyo
Keyword(s):  
Constitutive Model ◽  
Polymer Chain ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Molecular Chain ◽  
Dielectric Elastomers ◽  
Finite Extensibility ◽  
Single Polymer Chain ◽  
Non Gaussian

The mechanical response of dielectric elastomers can be influenced or even controlled by an imposed electric field. It can, for example, cause mechanical stress or strain without any applied load; this phenomenon is referred to as electrostriction. There are many purely phenomenological hyperelastic models describing this electroactive response of dielectric elastomers. In this contribution, we propose an electromechanical constitutive model based on molecular chain statistics. The model considers polarization of single polymer chain segments and takes into account their directional distribution. The latter results from non-Gaussian chain statistics, taking finite extensibility of polymer chains into account. The resulting (one-dimensional) electric potential of a single polymer chain is further generalized to the (three-dimensional) network potential. To this end, we apply directional averaging on the basis of numerical integration over a unit sphere. In a special case of the eight-direction (Arruda–Boyce) model, directional averaging is obtained analytically. This results in an invariant-based electroelastic constitutive model of dielectric elastomers. The model includes a small number of physically interpretable material constants and demonstrates good agreement with experimental data, with respect to the electroactive response and electrostriction of dielectric elastomers.

scholarly journals Direct observation of morphological transition for an adsorbed single polymer chain

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yukari Oda ◽  
Daisuke Kawaguchi ◽  
Yuma Morimitsu ◽  
Satoru Yamamoto ◽  
Keiji Tanaka
Keyword(s):  
Polymer Chain ◽  
Synthetic Polymer ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Morphological Transition ◽  
Nano Composite ◽  
Force Microscopy ◽  
Local Conformation ◽  
Atomic Force ◽  
Single Polymer Chain

AbstractA better understanding of the structure of polymers at solid interfaces is crucial for designing various polymer nano-composite materials from structural materials to nanomaterials for use in industry. To this end, the first step is to obtain information on how synthetic polymer chains adsorb onto a solid surface. We closely followed the trajectory of a single polymer chain on the surface as a function of temperature using atomic force microscopy. Combining the results with a full-atomistic molecular dynamics simulation revealed that the chain became more rigid on the way to reaching a pseudo-equilibrium state, accompanied by a change in its local conformation from mainly loops to trains. This information will be useful for regulating the physical properties of polymers at the interface.

scholarly journals A non-local diffusion equation arising in terminally attached polymer chains

1990 ◽  
Vol 1 (4) ◽  
pp. 311-326 ◽  
Author(s):  
Xinfu Chen ◽  
Avner Friedman
Keyword(s):  
Field Theory ◽  
Diffusion Equation ◽  
Polymer Chain ◽  
Mean Field Theory ◽  
Mean Field ◽  
Polymer Melt ◽  
Polymer Chains ◽  
Number Density ◽  
Non Local ◽  
Local Diffusion

We consider a polymer melt in a domain Ω whereby each polymer chain is attached at one endpoint to a fixed surface S contained in ∂Ω. Denote by G(x, t;y) the normalized number density of all subchains from x to y of length t. Then, according to the selfconsistent mean field theory, G satisfies, for each y: Gt - Δ2G + σϕG = 0, where σ is a real parameter, and ϕ is a functional of G(·, ·; ·) both non-local and nonlinear. We establish the existence of G and C∞ regularity of ϕ, as a function of x.

PHOTOLYSIS OF POLYMETHACRYLIC ACID IN AQUEOUS SOLUTIONS

1964 ◽  
Vol 42 (3) ◽  
pp. 522-531 ◽  
Author(s):  
C. H. Chou ◽  
H. H. G. Jellinek
Keyword(s):  
Aqueous Solutions ◽  
Chain Length ◽  
Polymer Chain ◽  
Irradiation Time ◽  
Polymer Concentration ◽  
Chain Scission ◽  
Polymer Chains ◽  
Polymethacrylic Acid ◽  
Degree Of Ionization ◽  
Ph Values

The photolysis of polymethacrylic acid was studied in aqueous solutions as a function of pH, polymer concentration, polymer chain length, and small additions of electrolytes in the absence of oxygen with light of wavelength 2537 Å. The random chain scission constants decrease with increasing pH values. Small variations in polymer chain length and concentration and electrolyte concentration have no effect on the photolysis. Changes in the ultraviolet spectra with irradiation time are more pronounced at low pH values than higher ones. It is shown that the decrease in susceptibility to photolysis with increasing degree of ionization of the acid is not proportional to the decrease or increase of the number of COOH or COO− groups respectively. It is rather due to the same causes—that is changes in ionic atmosphere— which make the polymer chains uncoil with increasing ionization.

scholarly journals Elucidating the Energetics and Effects of Solvents on Cellulose Hydrolysis Using a Polymeric Acid Catalyst

2018 ◽  
Vol 8 (10) ◽  
pp. 1767 ◽  
Author(s):  
Xiaoquan Sun ◽  
Xianghong Qian
Keyword(s):  
Free Energy ◽  
Catalytic Activity ◽  
Polymer Chain ◽  
Critical Role ◽  
Acid Catalyst ◽  
Cellulose Hydrolysis ◽  
Polymer Chains ◽  
Biomass Hydrolysis ◽  
Imidazolium Chloride ◽  
Polymeric Acid

A novel polymeric acid catalyst immobilized on a membrane substrate was found to possess superior catalytic activity and selectivity for biomass hydrolysis. The catalyst consists of two polymer chains, a poly(styrene sulfonic acid) (PSSA) polymer chain for catalyzing carbohydrate substrate, and a neighboring poly(vinyl imidazolium chloride) ionic liquid (PIL) polymer chain for promoting the solvation of the PSSA chain to enhance the catalytic activity. In order to elucidate the mechanism and determine the energetics of biomass catalytic processing using this unique catalyst, classical molecular dynamics (MD) coupled with metadynamics (MTD) simulations were conducted to determine the free energy surfaces (FES) of cellulose hydrolysis. The critical role that PIL plays in the catalytic conversion is elucidated. The solvation free energy and the interactions between PSSA, PIL, and cellulose chains are found to be significantly affected by the solvent.

scholarly journals EFFECT OF POLYMER CHAIN MODIFICATIONS ON ELASTOMER PROPERTIES

2019 ◽  
Vol 92 (1) ◽  
pp. 69-89 ◽  
Author(s):  
Katarzyna S. Bandzierz ◽  
Louis A. E. M. Reuvekamp ◽  
Jerzy Dryzek ◽  
Wilma K. Dierkes ◽  
Anke Blume ◽  
...  
Keyword(s):  
Polymer Chain ◽  
Crosslink Density ◽  
Mechanical Performance ◽  
Transition Process ◽  
Mechanical Analysis ◽  
Polymer Chains ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Scanning Calorimetry ◽  
Tetramethylthiuram Disulfide

ABSTRACT Considerable attention is paid to the influence of crosslink density and crosslink structures on the behavior of polymer chains and properties of elastomers. However, a very important parameter seems to be underestimated: the modifications to the polymer chains by curatives, formed by sulfur and fragments of accelerators. We draw attention to this important contribution to performance of spatial networks. The emulsion styrene–butadiene rubber samples, cured with tetramethylthiuram disulfide and sulfur (TMTD/S8) and zinc dialkyl dithiophosphate with sulfur (ZDT/S8), were studied. They were characterized in detail in terms of crosslink density and crosslink structures. Microscale techniques were used to obtain information about the behavior of the polymer chains: positron annihilation lifetime spectroscopy (PALS) to study the free volume structure and differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) to monitor the glass transition process. Properties such as static mechanical performance and thermo-oxidative stability were also evaluated. All of the investigated characteristics were influenced by a combination of crosslink density, crosslink structures, and, to a large extent, by the modifications of the polymer chains. The effect of the modifications is dependent on the amount and the structure of the curatives' molecules. On the basis of the obtained results, the usefulness of the “phr” unit used for calculation of the curatives' amount has been queried. Furthermore, it has been demonstrated that DSC, DMA, and PALS techniques can provide evidence for the presence of the modifications on the polymer chain by curatives.

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