Phase Behavior of a Flexible Star Polymer Chain in Good Solvent near an Attractive Surface

Douah, Sarra; Sabeur, Sid Ahmed

doi:10.1002/mats.201700074

Cited by 3 publications

(3 citation statements)

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“…56,57 Isolated stars on surfaces have been analyzed by Halperin and Joanny. 58,59 Potemkin studied the persistence length of strongly adsorbed comb-like chains. 60 The Monte Carlo method has been used to study stars at interfaces for relatively short stars.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In applications, for example, in shampoos, one makes use of branched macromolecules on a regular basis as well. − , The theoretical study of the interfacial behavior of branched macromolecules has a modest history . Some attention is given to the critical adsorption energy for branched macromolecules. , Isolated stars on surfaces have been analyzed by Halperin and Joanny. , Potemkin studied the persistence length of strongly adsorbed comb-like chains . The Monte Carlo method has been used to study stars at interfaces for relatively short stars …”

Section: Introductionmentioning

confidence: 99%

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Structure and Colloidal Stability of Adsorption Layers of Macrocycle, Linear, Comb, Star, and Dendritic Macromolecules

2020

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The equilibrium theory of polymer adsorption on a solid/liquid interface is well established. De Gennes explained that linear homopolymers adsorbing on a surface develop a proximal, central, and distal region in their adsorption profile, wherein the central region has a universal scaling self-similar structure with power-law coefficient −4/3. More pictorially, the layer is composed of trains, loops, and tails. Linear chains have just two tails, and therefore it is often assumed that the adsorption layer consists of loops only. Branched macromolecules have multiple tails, and the loops-only approach is argued to become progressively less accurate. Using self-consistent field theory of Scheutjens and Fleer (SF-SCF), we consider the macrocycle (chain without ends), linear, star-like, dendritic, and comb-like (homo)polymers and focus on the effects of tails. We show that the adsorption profile changes systematically with the degree of branching. Typically, for significantly branched chains the polymer density in the outer part of the central region has an effective scaling coefficient that may exceed the −4/3 value. Comb polymers adsorb with their backbone preferentially and generate a “brush”-like layer through adsorption, which we refer to as a hedge layer as the backbone and branches are hidden behind the free ends. By way of an array of “out-going” side chains, such a layer acts as a superb colloid stabilizer and as a lubricant, outperforming star-like polymers or dendritic polymers which qualitatively behave similar to linear chains.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure and Colloidal Stability of Adsorption Layers of Macrocycle, Linear, Comb, Star, and Dendritic Macromolecules

2020

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“…A large number of works have studied macromolecule adsorption on homogeneous or heterogeneous surfaces, focusing on the adsorption transition by means of coarse‐grained models in equilibrium conditions . The dynamics of single chains on attractive surfaces in the vicinity of the adsorption transition was studied through lattice models such as the bond fluctuation model and off‐lattice beadspring models and recently, the phase behavior of a star polymer chain has been simulated using a generic coarse‐grained model and the multicanonical Monte Carlo (MC) method . Several authors have focused on single chains with one end attached to the surface.…”

Section: Introductionmentioning

confidence: 99%

Conformational Changes and Dynamics during Adsorption of Macromolecules with Different Degree of Polymerization Studied by Monte Carlo Simulations

Serra

Cabanilles

Dueñas

et al. 2018

Macro Theory & Simulations

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such as polymers, ceramics, or metals is of paramount importance for tissue engineering and regenerative medicine applications. [7][8][9][10] Furthermore, knowledge of the structural formation at the solid/liquid interface is also a key factor in designing micro/nanostructures with promising applications in nanotechnology. [11,12] The phase transition of diluted macromolecules in equilibrium is characterized by conformational changes. [13] Macromolecules diluted in a good solvent favor random coil conformations at high temperatures. When the temperature drops, the macromolecules collapse and adopt a globular conformation with lower conformational entropy than coil structures. However, globular conformation is entropy-dominated and the system evolves toward crystalline conformations. [14][15][16] The presence of an attractive surface could assist adsorbed chains toward crystalline or nematic order, leading to configurations that do not occur on a nonadherent surface. [13,17,18] Reduced motion of a polymer chain is commonly found near the surface during adsorption. The attraction potential between the surface and the monomers is fundamental for the polymer chain to adsorb and remain on the surface. Concentration, temperature, and chain length influence the dynamics of the adsorbed polymer chains. [19] Meta-stable polymer states play an important role in polymer physics. Mainly dependent (though not exclusively) on temperature, the mobility of polymer chains is at times so hindered that meta-stable conformations remain over long periods of time. Both experiments [20] and simulations [21] have revealed the existence of thermodynamically meta-stable states during the coil-to-globule transition. This constraint on mobility produces the glass transition and structural relaxation phenomena. In the glass transition temperature range, the chains become frozen in an out-of-equilibrium state in which conformational motions are severely limited and only local movements are allowed. Below the glass transition temperature the system evolves toward equilibrium in what is known as structural relaxation. [22,23] Molecular simulations such as molecular dynamics [24][25][26][27] and coarse-grained models [28][29][30][31] have been extensively used to analyze both the static and dynamic properties of polymeric materials. By simplifying detailed chemistry and atomic details, Monte Carlo SimulationsDynamics of multilayer adsorption of macromolecules with different degree of polymerization is studied by coarse-grained Monte Carlo simulations, focusing on both the interface macromolecule-surface and chain-chain interaction in and out of equilibrium conditions. The interfacial interaction between the solid flat surface and the macromolecules is modeled by means of a Lennard-Jones potential, and inter-and intrachain interactions are simulated using bond angle, bond length, and Lennard-Jones potentials. The results show that local and conformational motions near the glass transition temperature promote configurations with minimal energy, wh...

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Monte Carlo simulation on the adsorption of polymer chains on polymer brushes

Wang¹,

Zhou²,

Wu³

et al. 2020

Acta Phys. Sin.

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<sec> The adsorption of polymer on surface is a hot topic in physical, chemical and biological communities, which is influenced by many factors, such as the topological structure and the flexibility of the polymer, the attractive interaction between the polymer and the surface, the detailed structure of the surface, etc. The adsorption of polymers on solid surfaces is extensively studied, while the adsorption behaviors of polymers on soft surfaces are still unclear.</sec><sec> In this work, the static and dynamical characters of the adsorption of a free polymer chain on polymer brushes are studied by using Monte Carlo simulation. The brush is formed by grafted polymers with length Nb and distance d. Results indicate that, with increasing the adsorption energy (ε) between the free polymer and the brush, the free polymer shows a phase transition from a desorbed state to an adsorbed state. Based on the dependence of the number of the adsorption segment of the free polymer (mad) on the adsorption energy ε, we defined the critical adsorption point (εC) where the phase transition occurs. εC is nearly independent of the length of the free polymer, but it increases with decreasing the length of the grafted polymer or increasing the distance between the grafted polymers. When ε < εC, the free polymer is desorbed and its size is the same as that in free space. When ε ≈ εC, the free polymer is sucked into the brush and meanwhile the size is compressed. While when ε <inline-formula><tex-math id="Z-20200813163453">\begin{document}$\gg $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="16-20200411_Z-20200813163453.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="16-20200411_Z-20200813163453.png"/></alternatives></inline-formula> εC, the free polymer is strongly adsorbed on the surface of the brush and forms a quasi two-dimensional conformation, and meanwhile the whole adsorption process contains two stages: the adsorption process of the free polymer and the diffusion process of the brush. Moreover, with the increase of ε, the diffusion of the free polymer shows an obvious transition from the normal model to the sub-diffusion model near εC. The transition of the diffusion model maybe useful for separation of polymers with different attractive polymer-brush interactions. For example, one may construct a brush surface and use it as a polymer separation device. Under weak driving force parallel to the surface, polymers with polymer-brush interaction ε < εC can move quickly, while polymers with ε > εC will move slowly or be trapped on the brush.</sec>

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Phase Behavior of a Flexible Star Polymer Chain in Good Solvent near an Attractive Surface

Cited by 3 publications

References 34 publications

Structure and Colloidal Stability of Adsorption Layers of Macrocycle, Linear, Comb, Star, and Dendritic Macromolecules

Structure and Colloidal Stability of Adsorption Layers of Macrocycle, Linear, Comb, Star, and Dendritic Macromolecules

Conformational Changes and Dynamics during Adsorption of Macromolecules with Different Degree of Polymerization Studied by Monte Carlo Simulations

Monte Carlo simulation on the adsorption of polymer chains on polymer brushes

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