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

Abstract

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...

Novel Cuboid-like Crystalline Complexes (CLCCs), Photon Emission, Fluorescent Fibers, and Bright Red Fabrics of Eu3+ Complexes Adjusted by Amphiphilic Molecules

“…These results indicate the following: (1) SA and HQ do not interfere with the ordered atom arrangement, but they help to adjust the crystal shape from irregular to regular as shown in Figure 1 ; (2) SA possesses a better function for both crystal shape (as shown in Figure 1 and Figure 8 ) and dispersion in the LDPE host (as shown in Figure 8 ). Thus, we think that ae flexible C–C link structure, such as SA, provides better conformation changeability [ 43 ].…”

Flexible Sensor for Invisible Respiratory Monitoring via Construction of a 2D Stacked Micronetwork

“…The mobility of molecular chains in a polymer is directly related to its thermal expansion coefficient. , When the movement of the molecular chain is sensitive to temperature, due to the increase in entropy, the oriented molecular chains are keen to shrink into a random coil, which exhibits a large volume expansion in the macroscopic view . POE, a typical thermoplastic elastomer, is composed of ethylene and octene segments.…”