Conformation and dynamics of a diluted chain in the presence of an adsorbing wall: A simulation with the bond fluctuation model

Serra, Roser Sabater i; Cabanilles, Constantino Torregrosa; Dueñas, José María Meseguer; Ribelles, J.L. Gómez; Molina‐Mateo, José

doi:10.1016/j.jnoncrysol.2014.05.009

Cited by 4 publications

(7 citation statements)

References 34 publications

(38 reference statements)

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“…In the previous studies, we had determined the values of the energy parameters in such a way that the behavior was representative of the chain and its interaction with the adsorbing surface. The chosen values were: V 0 = 0.4 for the bond angle potential, U 0 = 0.45 for the value of the bond length potential, and ε = 0.15 for the Lennard–Jones potential.…”

Section: Model and Simulation Methodsmentioning

confidence: 80%

“…This showed that the possible conformations of the chain were the result of the balance between inter‐ and intramolecular interactions added to the spatial restrictions imposed by the segment packing of the chain in globule or coil conformation. We subsequently introduced an adsorbing surface to the simulation space in order to study the surface–chain interaction . To model this interaction, we introduced an additional Lennard–Jones potential between the surface and the chain units following the equation

U_{LJ - surf} = 4 ε_{surf} ([], {(\frac{σ}{r})}^{12} - normal {(\frac{σ}{r})}^{6})

where σ was 2.0 lattice units, for consistency with the excluded volume imposed by the lattice conditions of the model used in the simulation.…”

Section: Model and Simulation Methodsmentioning

confidence: 99%

“…The sum of the 3 parameters was fixed at 1 (as previously) in order to be able to compare the temperature scale with the previous results. The surface–chain interaction parameter was selected to achieve the same intensity as the Lennard–Jones potential (ε surf = 0.15) in order to assess the competition between adsorption and globule formation phenomena …”

Section: Model and Simulation Methodsmentioning

confidence: 99%

“…In a previous study, the present authors analyzed the conformation and dynamics of a single long macromolecule applying different surface‐chain potential and thermal treatment by means of Monte Carlo simulations with the bond fluctuation model . Two competing processes were found: 1) adsorption of segments on the surface and 2) subsequent crystallization and vitrification of nonabsorbed segments, which formed glassy globules whose conformation depended on the energy parameters of the system.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we present the results obtained from a system with chains with different degree of polymerization, focusing both on the interface macromolecule‐surface and chain–chain interactions in and out of equilibrium conditions. From the previous study, we selected a Lennard–Jones potential between the adsorbing surface and the monomeric units that led to partial absorption. This specific Lennard–Jones potential yielded widely different conformations according to the thermal history.…”

Section: Introductionmentioning

confidence: 99%

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Conformational Changes and Dynamics during Adsorption of Macromolecules with Different Degree of Polymerization Studied by Monte Carlo 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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Section: Model and Simulation Methodsmentioning

confidence: 80%