Phase transitions in single macromolecules: Loop-stretch transition versus loop adsorption transition in end-grafted polymer chains

Abstract Graft polymers result when vinyl monomers are polymerized in the presence of natural rubber, either in solution or as latex, and some of the polymeric chains become attached to the rubber molecules. The properties of the natural rubber can be widely modified according to the nature and the amount of the grafted polymer. The polymer-modified natural rubber appears to be produced by direct growth of polymer chains on to rubber molecules rather than by a transfer reaction involving the rubber. Graft polymers of styrene and methyl methacrylate with natural rubber can be compounded and cured to give light-colored articles of good tensile strength, and rubber-methyl methacrylate graft polymers have outstanding flex-cracking and fatigue resistance.

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How does stiffness of polymer chains affect their adsorption transition?

The Journal of Chemical Physics ◽

10.1063/1.5139940 ◽

2020 ◽

Vol 152 (6) ◽

pp. 064901 ◽

Cited By ~ 4

Author(s):

A. Milchev ◽

K. Binder

Keyword(s):

Polymer Chains ◽

Adsorption Transition

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Effect of Structure of Polymers Grafted from Graphene Oxide on the Compatibility of Particles with a Silicone-Based Environment and the Stimuli-Responsive Capabilities of Their Composites

Nanomaterials ◽

10.3390/nano10030591 ◽

2020 ◽

Vol 10 (3) ◽

pp. 591 ◽

Cited By ~ 2

Author(s):

Monika Zygo ◽

Miroslav Mrlik ◽

Marketa Ilcikova ◽

Martina Hrabalikova ◽

Josef Osicka ◽

...

Keyword(s):

Molecular Weight ◽

Graphene Oxide ◽

Radical Polymerization ◽

Polymer Brushes ◽

Silicone Oil ◽

Polymer Chains ◽

Butyl Methacrylate ◽

Raman Shift ◽

Stimuli Responsive ◽

Grafted Polymer

This study reports the utilization of controlled radical polymerization as a tool for controlling the stimuli-responsive capabilities of graphene oxide (GO) based hybrid systems. Various polymer brushes with controlled molecular weight and narrow molecular weight distribution were grafted from the GO surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The modification of GO with poly(n-butyl methacrylate) (PBMA), poly(glycidyl methacrylate) (PGMA), poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) and poly(methyl methacrylate) (PMMA) was confirmed by thermogravimetric analysis (TGA) coupled with online Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Various grafting densities of GO-based materials were investigated, and conductivity was elucidated using a four-point probe method. Raman shift and XPS were used to confirm the reduction of surface properties of the GO particles during SI-ATRP. The contact angle measurements indicated the changes in the compatibility of GOs with silicone oil, depending on the structure of the grafted polymer chains. The compatibility of the GOs with poly(dimethylsiloxane) was also investigated using steady shear rheology. The tunability of the electrorheological, as well as the photo-actuation capability, was investigated. It was shown that in addition to the modification of conductivity, the dipole moment of the pendant groups of the grafted polymer chains also plays an important role in the electrorheological (ER) performance. The compatibility of the particles with the polymer matrix, and thus proper particles dispersibility, is the most important factor for the photo-actuation efficiency. The plasticizing effect of the GO-polymer hybrid filler also has a crucial impact on the matrix stiffness and thus the ability to reversibly respond to the external light stimulation.

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Use of the Complex Zeros of the Partition Function to Investigate the Critical Behavior of the Generalized Interacting Self-Avoiding Trail Model

Entropy ◽

10.3390/e21020153 ◽

2019 ◽

Vol 21 (2) ◽

pp. 153

Author(s):

Damien Foster ◽

Ralph Kenna ◽

Claire Pinettes

Keyword(s):

Phase Transitions ◽

Partition Function ◽

Critical Behavior ◽

Finite Size ◽

The Self ◽

Partition Function Zeros ◽

Adsorption Transition ◽

Function Zeros ◽

Complex Zeros ◽

Self Avoiding Walk

The complex zeros of the canonical (fixed walk-length) partition function are calculated for both the self-avoiding trails model and the vertex-interacting self-avoiding walk model, both in bulk and in the presence of an attractive surface. The finite-size behavior of the zeros is used to estimate the location of phase transitions: the collapse transition in the bulk and the adsorption transition in the presence of a surface. The bulk and surface cross-over exponents, ϕ and ϕ S , are estimated from the scaling behavior of the leading partition function zeros.

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Phase transitions of single polymer chains and of polymer solutions: insights from Monte Carlo simulations

Journal of Physics Condensed Matter ◽

10.1088/0953-8984/20/49/494215 ◽

2008 ◽

Vol 20 (49) ◽

pp. 494215 ◽

Cited By ~ 12

Author(s):

K Binder ◽

W Paul ◽

T Strauch ◽

F Rampf ◽

V Ivanov ◽

...

Keyword(s):

Monte Carlo ◽

Phase Transitions ◽

Monte Carlo Simulations ◽

Polymer Solutions ◽

Polymer Chains

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Oil Deposition on Polymer Brush-Coated NF Membranes

Membranes ◽

10.3390/membranes9120168 ◽

2019 ◽

Vol 9 (12) ◽

pp. 168 ◽

Cited By ~ 1

Author(s):

Anh Vu ◽

Naama Segev Mark ◽

Guy Z. Ramon ◽

Xianghong Qian ◽

Arijit Sengupta ◽

...

Keyword(s):

Membrane Fouling ◽

Membrane Surface ◽

Polymer Brush ◽

Operating Mode ◽

Feed Solution ◽

Polymer Chains ◽

Membrane Properties ◽

Solution Temperature ◽

Oil Droplets ◽

Grafted Polymer

Membrane-based processes are attractive for treating oily wastewaters. However, membrane fouling due to the deposition of oil droplets on the membrane surface compromises performance. Here, real-time observation of the deposition of oil droplets by direct confocal microscopy was conducted. Experiments were conducted in dead-end and crossflow modes. Base NF 270 nanofiltration membranes as well as membranes modified by grafting poly(N-isopropylacrylamide) chains from the membrane surface using atom transfer radical polymerization were investigated. By using feed streams containing low and high NaCl concentrations, the grafted polymer chains could be induced to switch conformation from a hydrated to a dehydrated state, as the lower critical solution temperature for the grafted polymer chains moved above and below the room temperature, respectively. For the modified membrane, it was shown that switching conformation of the grafted polymer chains led to the partial release of adsorbed oil. The results also indicate that, unlike particles such as polystyrene beads, adsorption of oil droplets can lead to coalescence of the adsorbed oil droplets on the membrane surface. The results provide further evidence of the importance of membrane properties, feed solution characteristics, and operating mode and conditions on membrane fouling.

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