Molecular and Energetic Descriptions of the Plasma Protein Adsorption onto the PVC Surface: Implications for Biocompatibility in Medical Devices.

Protein adsorption on material surfaces plays a key role in the biocompatibility of medical devices. Therefore, understanding the complex interplay of physicochemical factors driving this kind of biofouling is paramount for advancing biomaterial design. In this study, we investigated the interaction of the most prominent plasma proteins with polyvinyl chloride (PVC) as one of the ubiquitous materials in medical devices.

Toward a Better Understanding of the Poly(glycerol sebacate)-Water Interface.

Molecular simulations were conducted to provide a better description of the poly(glycerol sebacate) (PGS)-water interface. The density and the glass-transition temperature as well as their dependencies on the degree of esterification were examined in close connection with the available experimental data. The work of adhesion and water contact angle were calculated as a function of the degree of esterification.

Probing Enzymatic PET Degradation: Molecular Dynamics Analysis of Cutinase Adsorption and Stability.

Understanding the mechanisms influencing poly(ethylene terephthalate) (PET) biodegradation is crucial for developing innovative strategies to accelerate the breakdown of this persistent plastic. In this study, we employed all-atom molecular dynamics simulation to investigate the adsorption process of the LCC-ICCG cutinase enzyme onto the PET surface. Our results revealed that hydrophobic, π-π, and H bond interactions, specifically involving aliphatic, aromatic, and polar uncharged amino acids, were the primary driving forces for the adsorption of the cutinase enzyme onto PET.

Autohesion Mechanisms at Interfaces Between Random Copolymer Melts: Mesoscopic Simulations with Realistic Coarse-Grained Models.

The increase in welding time during the interdiffusion of a pair of non reacting random copolymer melts favors the strength rate of healing at the interface. Furthermore, the diffusion kinetic during the interpenetration of copolymer chains across the interface is strongly dependent on molecular weight. In this paper we perform mesoscopic simulations with realistic coarse grain models to study the autohesion mechanism across the interface between slightly entangled styrene-butadiene random copolymer melts.

Development of anisotropic force fields for homopolymer melts at the mesoscale.

With the aim of producing realistic coarse-grained models of homopolymers, we introduce a tabulated backbone-oriented anisotropic potential. The parameters of the model are optimized using statistical trajectory matching. The impact of grain anisotropy is evaluated at different coarse-graining levels using cis-polybutadiene as a test case.

A Consistent Thermodynamic Characterization of the Adsorption Process through the Calculation of Free Energy Contributions.

We apply in this study different methodologies based on thermodynamic integration (TI), free energy perturbation (FEP), and potential of mean force (PMF) to address the challenging issue of the calculation of the free energy of adsorption. A model system composed of a solid substrate, an adsorbate, and solvent particles is specifically designed to reduce the dependence of our free energy results on the sampling of the phase space and the choice of the pathway. The reliability and efficiency of these alchemical free energy simulations are established through the closure of a thermodynamic cycle describing the adsorption process in solution and in a vacuum.

Energetic and Structural Characterizations of the PET-Water Interface as a Key Step in Understanding Its Depolymerization.

We report molecular simulations of the interaction between poly(ethylene terephthalate) (PET) surfaces and water molecules with a short-term goal to better evaluate the different energy contributions governing the enzymatic degradation of amorphous PET. After checking that the glass transition temperature, density, entanglement mass, and mechanical properties of an amorphous PET are well reproduced by our molecular model, we extend the study to the extraction of a monomer from the bulk surface in different environments, i.e.

Impact of the Force Field on the Calculation of Density and Surface Tension of Epoxy-Resins.

The molecular simulation of interfacial systems is a matter of debate because of the choice of many input parameters that can affect significantly the performance of the force field of reproducing the surface tension and the coexisting densities. After developing a robust methodology for the calculation of the surface tension on a Lennard-Jones fluid, we apply it with different force fields to calculate the density and surface tension of pure constituents of epoxy resins. By using the model that best reproduces the experimental density and surface tension, we investigate the impact of composition in mass fraction on uncured epoxy resins and the effects of degree of cross-linking on cured resins.

Consistent and Transferable Force Fields for Statistical Copolymer Systems at the Mesoscale.

The statistical trajectory matching (STM) method was applied successfully to derive coarse grain (CG) models for bulk properties of homopolymers. The extension of the methodology for building CG models for statistical copolymer systems is much more challenging. We present here the strategy for developing CG models for styrene-butadiene-rubber, and we compare the quality of the resulting CG force fields on the structure and thermodynamics at different chemical compositions.

Molecular Simulations of Thermomechanical Properties of Epoxy-Amine Resins.

All-atom molecular dynamics (MD) simulations were performed with the CHARMM force field to characterize various epoxy resins, such as aliphatic and bisphenol-based resins. A multistep cross-linking algorithm was established, and key properties such as density, glass temperature, and elastic modulus were calculated. A quantitative comparison was made and was proven to be in good agreement with experimental data, with average absolute deviations between experiments and molecular simulation comprised between 2% and 12%.

Investigation of the Complexation between 4-Aminoazobenzene and Cucurbit[7]uril through a Combined Spectroscopic, Nuclear Magnetic Resonance, and Molecular Simulation Studies.

Cucurbiturils are well known for their ability to form supramolecular systems with ultrahigh affinities binding. Inclusion complex between 4-aminoazobenzene and cucurbit[7]uril has been investigated in aqueous solution by ultraviolet (UV)-spectroscopy, H NMR, and molecular simulations. 4-aminoazobenzene shows high affinity in acidic solutions while no association was detected in neutral solutions.

Molecular interactions at the metal-liquid interfaces.

We reported molecular simulations of the interactions among water, an epoxy prepolymer diglycidic ether of bisphenol A (DGEBA), and a hardener isophorone diamine (IPDA) on an aluminum surface. This work proposes a comprehensive thermodynamic characterization of the adhesion process from the calculation of different interfacial tensions. The cross-interactions between the atoms of the metal surface and different molecules are adjusted so as to reproduce the experimental work of adhesion.

Insulin Adsorption onto PE and PVC Tubings.

We investigate the adsorption of insulin onto PE and PVC materials by using HPLC measurements and computer simulations. We interpret the experiments by calculating the Gibbs free energy profiles during the adsorption process. The values of free energy of adsorption show a good agreement with the experimental measurements.

Enhancing the Thermostability of Engineered Laccases in Aqueous Betaine-Based Natural Deep Eutectic Solvents.

In recent years, natural deep eutectic solvents (NADESs) have gained increasing attention as promising nontoxic solvents for biotechnological applications, due to their compatibility with enzymes and ability to enhance their activity. Betaine-based NADESs at a concentration of 25 wt % in a buffered aqueous solution were used as media to inhibit thermal inactivation of POXA1b laccase and its five variants when incubated at 70 and 90 °C. All the tested laccases showed higher residual activity when incubated in NADES solutions, with a further enhancement achieved also for the most thermostable variant.

Rheological properties of polymer chains at a copper oxide surface: Impact of the chain length, surface coverage, and grafted polymer shape.

We employ a recently derived semirealistic set of coarse-grained interactions to simulate polymer brushes of cis-1,4-polybutadiene grafted on a cuprous-oxide surface within the framework of dissipative particle dynamics. We consider two types of brushes, I and Y, that differ in the way they are connected to the surface. Our model explores the impact of free polymer chain length, grafting density of the brush, and imposed shear rate on the structural and dynamic properties of complex metal oxide polymer interfaces.

Strain induced crystallization of polymers at and above the crystallization temperature by coarse-grained simulations.

We examine the behavior of short and long polymers by means of coarse-grained computer simulations of a by-polyvinyl alcohol inspired model. In particular, we focus on the structural changes in the monomer and polymer scales during cooling and the application of uni-axial true strain. The straining of long polymers results in the formation of a semi-crystalline system at temperatures well above the crystallization temperature, which allows for the study of strain induced crystallization.

Understanding and Characterizing the Drug Sorption to PVC and PE Materials.

Characterizing the sorption of drugs onto polyvinylchloride (PVC) and polyethylene (PE) materials in terms of thermodynamic adsorption properties and atomistic details (local arrangements, orientation, and diffusion) is fundamental for the development of alternative materials that would limit drug sorption phenomena and plasticizer release. Here, a combination of experiments and sophisticated calculations of potential of mean forces are carried out to investigate the sorption of paracetamol and diazepam to PE and PVC surfaces. The simulated Gibbs free energies of adsorption are in line with the experimental interpretations.

Assessing the derivation of time parameters from branched polymer coarse-grain model.

The parameterization of rheological models for polymers is often obtained from experiments via the top-down approach. This procedure allows us to determine good fitting parameters for homogeneous materials but is less effective for polymer mixtures. From a molecular simulation point of view, the timescales needed to derive those parameters are often accessed through the use of coarse-grain potentials.

Heterogeneity Effects in Highly Cross-Linked Polymer Networks.

Despite their level of refinement, micro-mechanical, stretch-based and invariant-based models, still fail to capture and describe all aspects of the mechanical properties of polymer networks for which they were developed. This is for an important part caused by the way the microscopic inhomogeneities are treated. The Elastic Network Model (ENM) approach of reintroducing the spatial resolution by considering the network at the level of its topological constraints, is able to predict the macroscopic properties of polymer networks up to the point of failure.

Backbone oriented anisotropic coarse grains for efficient simulations of polymers.

Despite the fact that anisotropic particles have been introduced to describe molecular interactions for decades, they have been poorly used for polymers because of their computing time overhead and the absence of a relevant proof of their impact in this field. We first report a method using anisotropic beads for polymers, which solves the computing time issue by considering that beads keep their principal orientation alongside the mean local backbone vector of the polymer chain, avoiding the computation of torques during the dynamics. Applying this method to a polymer bulk, we study the effect of anisotropic interactions vs isotropic ones for various properties such as density, pressure, topology of the chain network, local structure, and orientational order.

Multi-scale modeling of the polymer-filler interaction.

We report mesoscopic simulations of the interaction between a silica nanoparticle and cis-1,4-polybutadiene chains with realistic coarse-(CG) grained models. The CG models are obtained with a bottom-up Bayesian method based on trajectory matching of atomistic configurations of the system. We then investigate the structural properties of the interfacial region as a function of the grafting density and polymer chain length.

Development of Coarse-Grained Models for Polymers by Trajectory Matching.

Coarse-grained (CG) models allow for simulating the necessary time and length scales relevant to polymers. However, developing realistic force fields at the CG level is still a challenge because there is no guarantee that the CG model reproduces all the properties of the atomistic model. A recent promising method was proposed for small molecules using statistical trajectory matching.

Using hydrogenated and perfluorinated gases to probe the interactions and structure of fluorinated ionic liquids.

After studying the properties of a mixture of hydrogenated and fluorinated ionic liquids we have measured the solubility of perfluoromethane, perfluoroethane and perfluoropropane in 1-alkyl-3-methylimidazolium based ionic liquids with hydrogenated or fluorinated alkyl side-chains: 1-octyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide ([C8C1Im][NTf2]), 1-octyl-3-methylimidazolium bis[pentafluoroethylsulfonyl]amide ([C8C1Im][BETI]), 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-3-methylimidazolium bis[trifluoromethylsulfonyl]amide ([C8H4F13C1Im][NTf2]), and 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-3-methylimidazolium bis[pentafluoroethylsulfonyl]amide ([C8H4F13C1Im][BETI]). The ionic liquids expand on mixing and mix endothermally with a relatively high enthalpy of mixing (ΔmixH for [C8C1Im]x[C8H4F13C1Im](1-x)[NTf2] of ca. 0.

Investigation of Li Cation Coordination and Transportation, by Molecular Modeling and NMR Studies, in a LiNTf-Doped Ionic Liquid-Vinylene Carbonate Mixture.

To increase the safety and stability of lithium-ion batteries, the development of electrolytes based on ionic liquids (ILs) has gained a lot of attention in recent years. However, with graphite electrodes, neat ILs afford weak cycling performance in the absence of organic additives (e.g.

Improving Cellulose Dissolution in Ionic Liquids by Tuning the Size of the Ions: Impact of the Length of the Alkyl Chains in Tetraalkylammonium Carboxylate.

Twenty ionic liquids based on tetraalkylammonium cations and carboxylate anions have been synthesized, characterized, and tested for cellulose dissolution. The amount of cellulose dissolved in these ionic liquids depends strongly on the size of the ions: from 0 to 22 wt % cellulose can be dissolved at 90 °C. The best ionic liquids are less viscous and ammonium carboxylate based ionic liquids can dissolve as much as imidazolium-based ones.