Polymer Dynamics: Bulk and Nanoconfined Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Physics and Theory".

Deadline for manuscript submissions: closed (28 February 2022) | Viewed by 34389

Special Issue Editor


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Guest Editor
Department of Materials Science and Engineering, University of Fukui, Fukui 91082507, Japan
Interests: dynamics in supercooled liquids; glass transition dynamics of polymers; crystallization of polymers; dynamics in nanosized polymers; polymer adsorption at interfaces; AC chip nano-calorimetry; simulations

Special Issue Information

Dear Colleagues,

Relaxation phenomena of polymer molecules in the melt and solution states generally include complicated molecular processes, which arise from segmental connectivity and flexibility of chain molecules. One of the most characteristic features in supercooled polymeric systems is cooperativity in dynamics. This feature makes the dynamics of polymers be more complex. Although various efforts have been done to elucidate them, the molecular mechanism of polymer dynamics still remains unrevealed; in particular, understanding the relaxation processes based on chemical structures and molecular architectures is a long-standing issue in this field. Furthermore, anomalous dynamics in nanoconfined systems such as ultrathin films and nanoparticles have attracted much attention: their dynamics are quite different from those of the bulk systems, where interfacial (or surface) and finite-size effects play a significant role. The origin of the anomaly has not yet been fully understood.

This Special Issue of Polymer Dynamics aims to publish original papers and reviews that concern a wide range of polymer dynamics including segmental dynamics in polymer melts, solutions, and nanoconfined systems for both synthetic and biopolymers. Studies that focus on the structures and dynamics near the surface and interface are also welcome. In addition, the formation processes of specific structures during crystallization, adsorption, elongation, and fracture are of interest.

Prof. Sasaki Takashi
Guest Editor

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Keywords

  • viscoelasticity
  • glass transition dynamics
  • simulations
  • spectroscopy
  • mechanical properties
  • calorimetry
  • nanoconfined polymers
  • polymer solutions
  • adsorption
  • surface and interface

Published Papers (16 papers)

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Editorial

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3 pages, 167 KiB  
Editorial
Polymer Dynamics: Bulk and Nanoconfined Polymers
by Takashi Sasaki
Polymers 2022, 14(7), 1271; https://doi.org/10.3390/polym14071271 - 22 Mar 2022
Cited by 1 | Viewed by 1315
Abstract
The dynamics in polymeric systems affect various important properties including mechanical and thermal behaviors, and extensive studies in this field have been executed not only academically but also practically [...] Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)

Research

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12 pages, 2319 KiB  
Article
Approaching Polymer Dynamics Combining Artificial Neural Networks and Elastically Collective Nonlinear Langevin Equation
by Luis A. Miccio, Claudia Borredon, Ulises Casado, Anh D. Phan and Gustavo A. Schwartz
Polymers 2022, 14(8), 1573; https://doi.org/10.3390/polym14081573 - 12 Apr 2022
Cited by 3 | Viewed by 1799
Abstract
The analysis of structural relaxation dynamics of polymers gives an insight into their mechanical properties, whose characterization is used to qualify a given material for its practical scope. The dynamics are usually expressed in terms of the temperature dependence of the relaxation time, [...] Read more.
The analysis of structural relaxation dynamics of polymers gives an insight into their mechanical properties, whose characterization is used to qualify a given material for its practical scope. The dynamics are usually expressed in terms of the temperature dependence of the relaxation time, which is only available through time-consuming experimental processes following polymer synthesis. However, it would be advantageous to estimate their dynamics before synthesizing them when designing new materials. In this work, we propose a combined approach of artificial neural networks and the elastically collective nonlinear Langevin equation (ECNLE) to estimate the temperature dependence of the main structural relaxation time of polymers based only on the knowledge of the chemical structure of the corresponding monomer. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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24 pages, 5343 KiB  
Article
Semi-Crystalline Polyoxymethylene-co-Polyoxyalkylene Multi-Block Telechels as Building Blocks for Polyurethane Applications
by Matthias Hoffmann, Matthias Hermesmann, Matthias Leven, Walter Leitner and Thomas Ernst Müller
Polymers 2022, 14(5), 882; https://doi.org/10.3390/polym14050882 - 23 Feb 2022
Cited by 3 | Viewed by 3297
Abstract
Hydroxy-terminated polyoxymethylene-co-polyoxyalkylene multi-block telechels were obtained by a new methodology that allows for the formal substituting of ether units in polyether polyols with oxymethylene moieties. An interesting feature is that, unlike carbonate groups in polycarbonate and polyethercarbonate polyols, homopolymer blocks of [...] Read more.
Hydroxy-terminated polyoxymethylene-co-polyoxyalkylene multi-block telechels were obtained by a new methodology that allows for the formal substituting of ether units in polyether polyols with oxymethylene moieties. An interesting feature is that, unlike carbonate groups in polycarbonate and polyethercarbonate polyols, homopolymer blocks of polyoxymethylene moieties can be formed. The regular nature of polyoxymethylene blocks imparts a certain crystallinity to the polymer that can give rise to new properties of polyurethanes derived from such telechels. The synthesis, reaction sequence and kinetics of the formation of oligomeric hydroxy-terminated multi-block telechel polyoxymethylene moieties are discussed in this paper and the preparation of a polyurethane material is demonstrated. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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14 pages, 1892 KiB  
Article
Translocation, Rejection and Trapping of Polyampholytes
by Yeong-Beom Kim, Min-Kyung Chae, Jeong-Man Park, Albert Johner and Nam-Kyung Lee
Polymers 2022, 14(4), 797; https://doi.org/10.3390/polym14040797 - 18 Feb 2022
Cited by 3 | Viewed by 1344
Abstract
Polyampholytes (PA) are a special class of polymers comprising both positive and negative monomers along their sequence. Most proteins have positive and negative residues and are PAs. Proteins have a well-defined sequence while synthetic PAs have a random charge sequence. We investigated the [...] Read more.
Polyampholytes (PA) are a special class of polymers comprising both positive and negative monomers along their sequence. Most proteins have positive and negative residues and are PAs. Proteins have a well-defined sequence while synthetic PAs have a random charge sequence. We investigated the translocation behavior of random polyampholyte chains through a pore under the action of an electric field by means of Monte Carlo simulations. The simulations incorporated a realistic translocation potential profile along an extended asymmetric pore and translocation was studied for both directions of engagement. The study was conducted from the perspective of statistics for disordered systems. The translocation behavior (translocation vs. rejection) was recorded for all 220 sequences comprised of N = 20 charged monomers. The results were compared with those for 107 random sequences of N = 40 to better demonstrate asymptotic laws. At early times, rejection was mainly controlled by the charge sequence of the head part, but late translocation/rejection was governed by the escape from a trapped state over an antagonistic barrier built up along the sequence. The probability distribution of translocation times from all successful attempts revealed a power-law tail. At finite times, there was a population of trapped sequences that relaxed very slowly (logarithmically) with time. If a subensemble of sequences with prescribed net charge was considered the power-law decay was steeper for a more favorable net charge. Our findings were rationalized by theoretical arguments developed for long chains. We also provided operational criteria for the translocation behavior of a sequence, explaining the selection by the translocation process. From the perspective of protein translocation, our findings can help rationalize the behavior of intrinsically disordered proteins (IDPs), which can be modeled as polyampholytes. Most IDP sequences have a strong net charge favoring translocation. Even for sequences with those large net charges, the translocation times remained very dispersed and the translocation was highly sequence-selective. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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8 pages, 722 KiB  
Article
Adsorption Kinetics of Polystyrene and Poly(9-anthracenyl methyl methacrylate) onto SiO2 Surface Measured by Chip Nano-Calorimetry
by Mina Ishihara, Tomoya Watanabe and Takashi Sasaki
Polymers 2022, 14(3), 605; https://doi.org/10.3390/polym14030605 - 03 Feb 2022
Cited by 4 | Viewed by 1673
Abstract
The alternating current (AC) chip nano-calorimetry is a powerful tool to investigate the physical properties of polymer thin films. In this paper, we report on the adsorption kinetics of polymers in which an AC chip nano-calorimetry was used for the first time. This [...] Read more.
The alternating current (AC) chip nano-calorimetry is a powerful tool to investigate the physical properties of polymer thin films. In this paper, we report on the adsorption kinetics of polymers in which an AC chip nano-calorimetry was used for the first time. This technique allows for the real-time measurement of the adsorption kinetics of polymer chains onto the SiO2 surface. We used polystyrene (PS) and poly(9-anthracenyl methyl methacrylate) (PAMMA), which have different chemical natures and side group sizes. It was confirmed that the observed adsorption kinetics for PS were consistent with previously reported results obtained by dielectric spectroscopy. For PAMMA, we found characteristic adsorption kinetics, which shows a clear kink at the crossover between the early and later stages, while PS exhibits a lesser tendency of showing the kink as demonstrated by previously reported results. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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14 pages, 2033 KiB  
Article
Sliding Dynamics of Ring Chains on Two Asymmetric/Symmetric Chains in a Simple Slide-Ring Gel
by Jiaxin Wu, Fuchen Guo, Ke Li and Linxi Zhang
Polymers 2022, 14(1), 79; https://doi.org/10.3390/polym14010079 - 26 Dec 2021
Cited by 7 | Viewed by 2295
Abstract
The sliding dynamics along two asymmetric/symmetric axial chains of ring chains linked by a linear chainis investigated using molecular dynamics (MD) simulations. A novel sub-diffusion behavior is observed for ring chains sliding along eithera fixed rod-like chain or fluctuating axial chain on asymmetric/symmetric [...] Read more.
The sliding dynamics along two asymmetric/symmetric axial chains of ring chains linked by a linear chainis investigated using molecular dynamics (MD) simulations. A novel sub-diffusion behavior is observed for ring chains sliding along eithera fixed rod-like chain or fluctuating axial chain on asymmetric/symmetric axial chainsat the intermediate time range due to their strongly interplay between two ring chains. However, two ring chains slide in the normal diffusion at along time range because their sliding dynamics can be regarded as an overall motion of two ring chains. For ring chains sliding on two symmetric/asymmetricaxial chains, the diffusion coefficient D of ring chains relies on the bending energy of axial chains (Kb) as well as the distance of two axial chains (d). There exists a maximum diffusion coefficient Dmax at d = d* in which ring chains slide at the fastest velocity due to the maximum conformational entropy for the linking chain between two ring chainsat d = d*. Ring chain slide on fixed rod-like axial chainsfaster in the symmetric axial chain case than that in the asymmetric axial chain case. However, ring chains slide on fluctuatingaxial chainsslower in the symmetric axial chain case than that in the asymmetric axial chain case. This investigation can provide insights into the effects of the linked chain conformation on the sliding dynamics of ring chains in a slide-ring gel. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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18 pages, 7142 KiB  
Article
New Considerations on the Determination of the Apparent Shear Viscosity of Polymer Melt with Micro Capillary Dies
by Wangqing Wu, Ke Zeng, Baishun Zhao, Fengnan Duan and Fengze Jiang
Polymers 2021, 13(24), 4451; https://doi.org/10.3390/polym13244451 - 18 Dec 2021
Cited by 3 | Viewed by 2616
Abstract
Capillary rheometers have been widely used for the rheological measurement of polymer melts. However, when micro capillary dies are used, the results are usually neither accurate nor consistent, even under the same measurement conditions. In this work, theoretical modeling and experimental studies were [...] Read more.
Capillary rheometers have been widely used for the rheological measurement of polymer melts. However, when micro capillary dies are used, the results are usually neither accurate nor consistent, even under the same measurement conditions. In this work, theoretical modeling and experimental studies were conducted for a more profound understanding of the mechanism by which the initial and boundary conditions influence the inaccuracy in the apparent shear viscosity determination with micro capillary dies (diameters: 500 μm, 200 μm, 100 μm). The results indicate that the amount of polymer initially in the barrel, the pre-compaction pressure and the capillary die diameter have a significant influence on the development of the micro scale inlet pressure, which directly determines the accuracy of the measurement at low and medium shear rates. The varying melt compressibility was confirmed to be the main factor directly related to the inaccuracy in the micro scale apparent shear viscosity determination. It is suggested that measures such as reducing the amount of polymer initially in the barrel and increasing the pre-compaction pressure could be used to reduce the measurement inaccuracy. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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11 pages, 3945 KiB  
Article
Impact of Magnesium Salt on the Mechanical and Thermal Properties of Poly(vinyl alcohol)
by Riza Asmaa Saari, Muhammad Shahrulnizam Nasri, Takumitsu Kida and Masayuki Yamaguchi
Polymers 2021, 13(21), 3760; https://doi.org/10.3390/polym13213760 - 30 Oct 2021
Cited by 3 | Viewed by 2011
Abstract
The effects of magnesium salts with various anion species on the structure and properties of a poly(vinyl alcohol) (PVA) film were studied. The glass transition temperature of the PVA film increased following the addition of a magnesium salt. Furthermore, the salt greatly enhanced [...] Read more.
The effects of magnesium salts with various anion species on the structure and properties of a poly(vinyl alcohol) (PVA) film were studied. The glass transition temperature of the PVA film increased following the addition of a magnesium salt. Furthermore, the salt greatly enhanced the modulus and yield stress and reduced the crystallinity of the film. These effects were attributed to the strong ion–dipole interactions between the magnesium salts and the PVA chains. The strength of interaction, i.e., the reduction of segmental motions, depended on the anion species in the following order: Mg(ClO4)2, MgBr2, MgCl2, Mg(CH3COO)2, and MgSO4. The order corresponded to the Hofmeister series, which predicts the ability to break the structure of water. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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14 pages, 2992 KiB  
Article
A Dynamically Correlated Network Model for the Collective Dynamics in Glass-Forming Molecular Liquids and Polymers
by Takashi Sasaki, Yuya Tsuzuki and Tatsuki Nakane
Polymers 2021, 13(19), 3424; https://doi.org/10.3390/polym13193424 - 06 Oct 2021
Cited by 3 | Viewed by 1551
Abstract
The non-Arrhenius behavior of segmental dynamics in glass-forming liquids is one of the most profound mysteries in soft matter physics. In this article, we propose a dynamically correlated network (DCN) model to understand the growing behavior of dynamically correlated regions during cooling, which [...] Read more.
The non-Arrhenius behavior of segmental dynamics in glass-forming liquids is one of the most profound mysteries in soft matter physics. In this article, we propose a dynamically correlated network (DCN) model to understand the growing behavior of dynamically correlated regions during cooling, which leads to the viscous slowdown of supercooled liquids. The fundamental concept of the model is that the cooperative region of collective motions has a network structure that consists of string-like parts, and networks of various sizes interpenetrate each other. Each segment undergoes dynamical coupling with its neighboring segments via a finite binding energy. Monte Carlo simulations showed that the fractal dimension of the DCNs generated at different temperatures increased and their size distribution became broader with decreasing temperature. The segmental relaxation time was evaluated based on a power law with four different exponents for the activation energy of rearrangement with respect to the DCN size. The results of the present DCN model are consistent with the experimental results for various materials of molecular and polymeric liquids. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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10 pages, 2133 KiB  
Article
Using Plasma Etching to Access the Polymer Density Distribution and Diffusivity of Gel Particles
by Ivan J. Suarez, Benjamin Sierra-Martin and Antonio Fernandez-Barbero
Polymers 2021, 13(15), 2537; https://doi.org/10.3390/polym13152537 - 31 Jul 2021
Cited by 1 | Viewed by 1432
Abstract
In this paper we examine the polymer density distribution of gel particles and its effect on solvent diffusivity through the polymer network. In order to access the inner particle regions, external polymer layers were removed by plasma etching, thus reducing them from the [...] Read more.
In this paper we examine the polymer density distribution of gel particles and its effect on solvent diffusivity through the polymer network. In order to access the inner particle regions, external polymer layers were removed by plasma etching, thus reducing them from the outside. Higher polymer densities after erosion showed internal heterogeneity, with the density increasing towards the center of the particles. An exponential decay polymer density model is proposed, and the spatial relaxation length measured. The diffusion of solvent through the particles, before and after the plasma oxidation, revealed a correlation between the diffusion coefficient and the internal density. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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18 pages, 3617 KiB  
Article
Plasma Supported Deposition of Amorphous Hydrogenated Carbon (a-C:H) on Polyamide 6: Determining Interlayer Completion and Dehydrogenation Effects during Layer Growth
by Torben Schlebrowski, Henriette Lüber, Lucas Beucher, Melanie Fritz, Youssef Benjillali, Mohammed Bentaouit, Barbara Hahn, Stefan Wehner and Christian B. Fischer
Polymers 2021, 13(11), 1886; https://doi.org/10.3390/polym13111886 - 06 Jun 2021
Cited by 5 | Viewed by 2060
Abstract
Polyamide 6 (PA6) is a commonly used material in many different sectors of modern industry. Herein, PA6 samples were coated with amorphous carbon layers (a-C:H) with increasing thickness up to 2 µm using radio frequency plasma enhanced chemical vapor deposition for surface adjustment. [...] Read more.
Polyamide 6 (PA6) is a commonly used material in many different sectors of modern industry. Herein, PA6 samples were coated with amorphous carbon layers (a-C:H) with increasing thickness up to 2 µm using radio frequency plasma enhanced chemical vapor deposition for surface adjustment. The morphology of the carbon coatings was inspected by ex situ atomic force microscopy and scanning electron microscopy. Surface wettability was checked by contact angle measurements. The chemical composition was analyzed using the surface sensitive synchrotron X-ray-based techniques near-edge X-ray absorption fine structure and X-ray photoelectron spectroscopy, supported by diffuse reflectance infrared Fourier transform spectroscopy. Particular attention was paid to the coating interval from 0 to 100 nm, to specify the interlayer thickness between the PA6 polymer and a-C:H coating, and the region between 1000 and 2000 nm, where dehydrogenation of the a-C:H layer occurs. The interlayer is decisive for the linkage of the deposited carbon layer on the polymer: the more pronounced it is, the better the adhesion. The thickness of the interlayer could be narrowed down to 40 nm in all used methods, and the dehydrogenation process takes place at a layer thickness of 1500 nm. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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13 pages, 3104 KiB  
Article
Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester
by Andrey Galukhin, Roman Nosov, Ilya Nikolaev, Elena Melnikova, Daut Islamov and Sergey Vyazovkin
Polymers 2021, 13(11), 1686; https://doi.org/10.3390/polym13111686 - 21 May 2021
Cited by 13 | Viewed by 2049
Abstract
A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the [...] Read more.
A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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23 pages, 8033 KiB  
Article
Entropy-Driven Heterogeneous Crystallization of Hard-Sphere Chains under Unidimensional Confinement
by Pablo Miguel Ramos, Miguel Herranz, Katerina Foteinopoulou, Nikos Ch. Karayiannis and Manuel Laso
Polymers 2021, 13(9), 1352; https://doi.org/10.3390/polym13091352 - 21 Apr 2021
Cited by 10 | Viewed by 2005
Abstract
We investigate, through Monte Carlo simulations, the heterogeneous crystallization of linear chains of tangent hard spheres under confinement in one dimension. Confinement is realized through flat, impenetrable, and parallel walls. A wide range of systems is studied with respect to their average chain [...] Read more.
We investigate, through Monte Carlo simulations, the heterogeneous crystallization of linear chains of tangent hard spheres under confinement in one dimension. Confinement is realized through flat, impenetrable, and parallel walls. A wide range of systems is studied with respect to their average chain lengths (N = 12 to 100) and packing densities (φ = 0.50 to 0.61). The local structure is quantified through the Characteristic Crystallographic Element (CCE) norm descriptor. Here, we split the phenomenon into the bulk crystallization, far from the walls, and the projected surface crystallization in layers adjacent to the confining surfaces. Once a critical volume fraction is met, the chains show a phase transition, starting from regions near the hard walls. The established crystal morphologies consist of alternating hexagonal close-packed or face-centered cubic layers with a stacking direction perpendicular to the confining walls. Crystal layer perfection is observed with an increasing concentration. As in the case of the unconstrained phase transition of athermal polymers at high densities, crystal nucleation and growth compete with the formation of sites of a fivefold local symmetry. While surface crystallites show perfection with a predominantly triangular character, the morphologies of square crystals or of a mixed type are also formed. The simulation results show that the rate of perfection of the surface crystallization is not significantly faster than that of the bulk crystallization. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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15 pages, 3033 KiB  
Article
Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating
by Tatyana Kirila, Anna Smirnova, Alla Razina, Andrey Tenkovtsev and Alexander Filippov
Polymers 2021, 13(7), 1152; https://doi.org/10.3390/polym13071152 - 04 Apr 2021
Cited by 9 | Viewed by 1933
Abstract
The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration [...] Read more.
The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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16 pages, 1772 KiB  
Article
Hysteretic Swelling/Deswelling of Polyelectrolyte Brushes and Bilayer Films in Response to Changes in pH and Salt Concentration
by Nisha Hollingsworth and Ronald G. Larson
Polymers 2021, 13(5), 812; https://doi.org/10.3390/polym13050812 - 06 Mar 2021
Cited by 8 | Viewed by 2045
Abstract
Abstract We use a quartz crystal microbalance with dissipation (QCM-D) to investigate the swelling/de-swelling and hysteresis in brushes of weakly ionizable polyanion poly(acrylic acid) (PAA) brushes and bilayers containing a PAA brush and a poly(ethylene imine) (PEI) overlayer [...] Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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Review

Jump to: Editorial, Research

20 pages, 6935 KiB  
Review
Review on Interfacial Bonding Mechanism of Functional Polymer Coating on Glass in Atomistic Modeling Perspective
by Hyunhang Park and Sung Hoon Lee
Polymers 2021, 13(14), 2244; https://doi.org/10.3390/polym13142244 - 08 Jul 2021
Cited by 11 | Viewed by 3602
Abstract
Atomistic modeling methods are successfully applied to understand interfacial interaction in nanoscale size and analyze adhesion mechanism in the organic–inorganic interface. In this paper, we review recent representative atomistic simulation works, focusing on the interfacial bonding, adhesion strength, and failure behavior between polymer [...] Read more.
Atomistic modeling methods are successfully applied to understand interfacial interaction in nanoscale size and analyze adhesion mechanism in the organic–inorganic interface. In this paper, we review recent representative atomistic simulation works, focusing on the interfacial bonding, adhesion strength, and failure behavior between polymer film and silicate glass. The simulation works are described under two categories, namely non-bonded and bonded interaction. In the works for non-bonded interaction, three main interactions, namely van der Waals interaction, polar interaction, and hydrogen bonds, are investigated, and the contributions to interfacial adhesion energy are analyzed. It is revealed that the most dominant interaction for adhesion is hydrogen bonding, but flexibility of the polymer film and modes of adhesion measurement test do affect adhesion and failure behavior. In the case of bonded interactions, the mechanism of covalent silane bond formation through condensation and hydrolysis process is reviewed, and surface reactivity, molecular density, and adhesion properties are calculated with an example of silane functionalized polymer. Besides interfacial interactions, effects of external conditions, such as surface morphology of the glass substrate and relative humidity on the adhesion and failure behavior, are presented, and modeling techniques developed for building interfacial system and calculating adhesion strengths are briefly introduced. Full article
(This article belongs to the Special Issue Polymer Dynamics: Bulk and Nanoconfined Polymers)
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