Thermodynamic properties of swollen polymer networks containing free polymer chains

1995 ◽  
Vol 101 ◽  
pp. 159
Author(s):  
Ferenc Horkay ◽  
Anne-Marie Hecht ◽  
Erik Geissler
Keyword(s):  
Thermodynamic Properties ◽  
Polymer Networks ◽  
Polymer Chains

The effect of blob size in polymer networks on nanoparticle-mediated adhesion of hydrogels

Soft Matter ◽  
2019 ◽  
Vol 15 (48) ◽  
pp. 9942-9948
Author(s):  
Sohyun Kim ◽  
Tae Hui Kang ◽  
Gi-Ra Yi
Keyword(s):  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Pore Diameter ◽  
Physical Adsorption ◽  
Mesoporous Silica Nanoparticles ◽  
Polymer Networks ◽  
Mesh Size ◽  
Adhesion Energy ◽  
Polymer Chains

Mesoporous silica nanoparticles can be used as an adhesive for hydrogels due to their physical adsorption to polymer chains, in which adhesion energy can be affected by the ratio of mesh size and pore diameter.

Neutron Reflection Studies of Swelling of Chemically End-Grafted Polymer Chains

1994 ◽  
Vol 376 ◽  
Author(s):  
Alamgir Karim ◽  
S.K. Satija ◽  
P. Gallagher ◽  
J.F. Douglas ◽  
L.J. Fetters
Keyword(s):  
Polymer Networks ◽  
The Body ◽  
Polymer Chains ◽  
Cross Linking ◽  
Neutron Reflection ◽  
Grafted Polymer ◽  
Solvent Quality ◽  
Grafting Density ◽  
Fluctuation Effects ◽  
Theta Solvent

ABSTRACTNeutron reflection is used to compare the swelling of two chemically end-grafted polystyrene brushes having different grafting densities exposed to a theta solvent cyclohexane and to a good solvent toluene. The relative swelling of tie brushes with a variation of solvent quality becomes smaller and the temperature dependence becomes weaker with an increase of grafting density. This type of swelling is very similar to polymer networks where an increase of cross-linking density leads to a decreased range of swelling and diminished dependence of the swelling. Our model density profile fits to the body of both brushes is parabolic in a good solvent so that some fluctuation effects, as found generally in lower density brushes, are obtained as the brush expands.

scholarly journals Benzil Photoperoxidations in Polymer Films and Crosslinking by the Resultant Benzoyl Peroxides in Polystyrene and Other Polymers

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5154
Author(s):  
Ivan Lukáč ◽  
Branislav Husár ◽  
Martin Danko ◽  
Richard G. Weiss
Keyword(s):  
Molecular Weight ◽  
Polymer Films ◽  
Glassy Polymer ◽  
Polymer Networks ◽  
Polymer Chains ◽  
Solid Surfaces ◽  
Low Molecular Weight ◽  
Long Wavelength ◽  
Covalently Linked ◽  
Phenyl Vinyl

Benzil (BZ) can be converted almost quantitatively to benzoyl peroxide (BP) in aerated polymer films upon irradiation at >400 nm (i.e., the long-wavelength edge of the n→π* absorption band of BZ, where BP does not absorb). Here, we summarize results for the photoperoxidation of BZ structures with molecular oxygen, principally in glassy polymer matrices. Some of the polymers are doped directly with BZ or its derivatives, and others, contain covalently attached BZ pendant groups from which BP groups are derived. While the decomposition of low-molecular-weight BP doped into polymer films (such as those of polystyrene (PS)) results in a net decrease in polymer molecular weight, thermal decomposition of pendant BP groups is an efficient method for chain crosslinking. Crosslinking of PS films doped with a molecule containing two covalently linked BZ or BP groups proceeds in a similar fashion. Free radicals from the covalently attached BP allow grafting of new monomers, as well. Additionally, the use of radiation filtered through masks has been used to create patterns of polymers on solid surfaces. Crosslinking of photodegradable poly(phenyl vinyl ketone) with BP structures obtained by photoperoxidation of BZ structures for the preparation of photodegradable polymer networks is described as well. In sum, the use of BZ and BP and their derivatives offers simple and convenient routes for modifying polymer chains and, especially, for crosslinking them. Specific applications of each use and process are provided. Although applications with PS are featured here, the methodologies described are amenable to a wide variety of other polymers.

Modeling fracture in rate-dependent polymer networks: A quasicontinuum approach

2021 ◽  
pp. 1-22
Author(s):  
Ahmed Ghareeb ◽  
Ahmed Elbanna
Keyword(s):  
Adaptive Mesh Refinement ◽  
Polymer Networks ◽  
Viscoelastic Behavior ◽  
Adaptive Mesh ◽  
Soft Materials ◽  
Polymer Chains ◽  
Loading Rates ◽  
Viscous Forces ◽  
Rate Dependent ◽  
Bond Breakage

Abstract Soft materials, such as rubber and gels, exhibit rate-dependent response where the stiffness, strength and fracture patterns depend largely on loading rates. Thus, accurate modeling of the mechanical behavior requires accounting for different sources of rate-dependence such as the intrinsic viscoelastic behavior of the polymer chains and the dynamic bond breakage and formation mechanism. In this chapter, we extend the QC approach presented in Ghareeb and Elbanna [Journal of the Mechanics and Physics of Solids, 137, 103819 (2020)] to include ratedependent behavior of polymer networks. We propose a homogenization rule for the viscous forces in the polymer chains and update the adaptive mesh refinement algorithm to account for dynamic bond breakage. Then, we use nonlinear finite element framework with predictorcorrector scheme to solve for the nodal displacements and velocities. We demonstrate the accuracy of the method by verifying it against fully discrete simulations for different examples of network structures and loading conditions. We further use the method to investigate the effects of the loading rates on the fracture characteristics of networks with different ratedependent parameters. Finally, We discuss the implications of the extended method for multiscale analysis of fracture in rate-dependent polymer networks.

scholarly journals Multivalent Ions as Reactive Crosslinkers for Biopolymers—A Review

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1840 ◽  
Author(s):  
Florian Wurm ◽  
Barbara Rietzler ◽  
Tung Pham ◽  
Thomas Bechtold
Keyword(s):  
Surface Modification ◽  
Polymer Networks ◽  
Polymer Chains ◽  
Textile Fibers ◽  
Ionic Crosslinking ◽  
Surfaces And Interfaces ◽  
Multivalent Ions ◽  
Functional Models ◽  
Controlled Adsorption ◽  
Ionic Crosslinks

Many biopolymers exhibit a strong complexing ability for multivalent ions. Often such ions form ionic bridges between the polymer chains. This leads to the formation of ionic cross linked networks and supermolecular structures, thus promoting the modification of the behavior of solid and gel polymer networks. Sorption of biopolymers on fiber surfaces and interfaces increases substantially in the case of multivalent ions, e.g., calcium being available for ionic crosslinking. Through controlled adsorption and ionic crosslinking surface modification of textile fibers with biopolymers can be achieved, thus altering the characteristics at the interface between fiber and surrounding matrices. A brief introduction on the differences deriving from the biopolymers, as their interaction with other compounds, is given. Functional models are presented and specified by several examples from previous and recent studies. The relevance of ionic crosslinks in biopolymers is discussed by means of selected examples of wider use.

scholarly journals Mobility of bound water in PNIPAM microgels

2021 ◽  
Author(s):  
Tetyana Kyrey ◽  
Judith Witte ◽  
Jana Lutzki ◽  
Michaela Zamponi ◽  
Stefan Wellert ◽  
...  
Keyword(s):  
Crucial Role ◽  
Polymer Networks ◽  
Bound Water ◽  
Polymer Chains ◽  
Stimuli Responsive ◽  
Solvent Interactions ◽  
Polymer Solvent

Polymer-solvent interactions play a crucial role in the stimuli-responsive behaviour of polymer networks. They infuence the swelling/deswelling behaviour as well as the dynamics of the polymer chains. Scattering experiments provide...

Physical Adsorption of Polymers on Disordered Filler Surfaces

1995 ◽  
Vol 68 (1) ◽  
pp. 26-36 ◽  
Author(s):  
Gert Heinrich ◽  
Thomas A. Vilgis
Keyword(s):  
Carbon Black ◽  
Physical Adsorption ◽  
Polymer Networks ◽  
Particle Surface ◽  
Configurational Entropy ◽  
Polymer Chains ◽  
Filled Polymer ◽  
Fractal Surfaces ◽  
The Difference ◽  
Surface Dimension

Abstract The problem of polymer adsorption on carbon black surfaces is considered within the concept of disorder-induced localization of polymer chains on disordered or fractal surfaces. The model describes how physical adsorption properties are enhanced compared to the adsorption on a flat surface. The difference is based on the configurational entropy which is less restricted in the disordered case than in the flat case. In fact, the surface of the carbon black particles is disordered over certain length scales and several experimental techniques have shown that the particle surface is fractal. This fractal nature can be quantified by the surface spectral density and the noninteger fractal surface dimension. As a main consequence, the coupling between filler and polymer is caused by entanglements formed between tightly adsorbed bound rubber on the filler surface and the bulk rubber far removed from the surface. The corresponding density of couples is estimated for several filled polymer networks using tensile test results. The stress-strain relations used are based on a new rigorous molecular-statistical model of filled polymer networks with quenched topology that includes the entanglements within the mobile rubber phase (configurational tube-model).

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