Role of the water matric potential (ΨM) and of equilibrium water content (EWC) on the water self-diffusion coefficient and on the oxygen permeability in hydrogel contact lenses

In this study, silicone-based hydrogel contact lenses were prepared by the polymerization of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane (TRIS), N,N-dimethylacrylamide (DMA), 1-vinyl-2-pyrrolidinone (NVP), and 2-hydroxyethylmethacrylate (HEMA). The properties of silicone hydrogel lenses were analyzed based on the methods such as equilibrium water content, oxygen permeability, optical transparency, contact angle, mechanical test, protein adsorption, and cell toxicity. The results showed that the TRIS content in all formulations increased the oxygen permeability and decreased the equilibrium water content, while both DMA and NVP contributed the hydrophilicity of the hydrogels. The maximum value of oxygen permeability was 74.9 barrers, corresponding to an equilibrium water content of 44.5% as well as a contact angle of 82°. Moreover, L929 fibroblasts grew on all these hydrogels, suggesting non-cytotoxicity. In general, the silicone hydrogels in this work exhibited good oxygen permeability, stiffness, and optical transparency as well as anti-protein adsorption. Hence, these silicone hydrogel polymers would be feasible for making contact lens.

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Role of triplet correlations in anomalous self-diffusion coefficient

Chemical Physics ◽

10.1016/j.chemphys.2012.06.009 ◽

2012 ◽

Vol 405 ◽

pp. 60-66

Author(s):

Gaganpreet ◽

Sunita Srivastava ◽

K. Tankeshwar

Keyword(s):

Diffusion Coefficient ◽

Self Diffusion ◽

Self Diffusion Coefficient

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Effect of Modification on the Fluid Diffusion Coefficient in Silica Nanochannels

Molecules ◽

10.3390/molecules26134030 ◽

2021 ◽

Vol 26 (13) ◽

pp. 4030

Author(s):

Gengbiao Chen ◽

Zhiwen Liu

Keyword(s):

Diffusion Coefficient ◽

Diffusion Coefficients ◽

Surface Effect ◽

Bulk Water ◽

Self Diffusion ◽

Average Diffusion Coefficient ◽

Average Diffusion ◽

Chain Lengths ◽

Fluid Diffusion ◽

Self Diffusion Coefficient

The diffusion behavior of fluid water in nanochannels with hydroxylation of silica gel and silanization of different modified chain lengths was simulated by the equilibrium molecular dynamics method. The diffusion coefficient of fluid water was calculated by the Einstein method and the Green–Kubo method, so as to analyze the change rule between the modification degree of nanochannels and the diffusion coefficient of fluid water. The results showed that the diffusion coefficient of fluid water increased with the length of the modified chain. The average diffusion coefficient of fluid water in the hydroxylated nanochannels was 8.01% of the bulk water diffusion coefficient, and the diffusion coefficients of fluid water in the –(CH2)3CH3, –(CH2)7CH3, and –(CH2)11CH3 nanochannels were 44.10%, 49.72%, and 53.80% of the diffusion coefficients of bulk water, respectively. In the above four wall characteristic models, the diffusion coefficients in the z direction were smaller than those in the other directions. However, with an increase in the silylation degree, the increased self-diffusion coefficient due to the surface effect could basically offset the decreased self-diffusion coefficient owing to the scale effect. In the four nanochannels, when the local diffusion coefficient of fluid water was in the range of 8 Å close to the wall, Dz was greater than Dxy, and beyond the range of 8 Å of the wall, the Dz was smaller than Dxy.

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Insights into the interactions and dynamics of a DES formed by phenyl propionic acid and choline chloride

Scientific Reports ◽

10.1038/s41598-021-85260-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Parisa Jahanbakhsh Bonab ◽

Alireza Rastkar Ebrahimzadeh ◽

Jaber Jahanbin Sardroodi

Keyword(s):

Diffusion Coefficient ◽

Liquid Phase ◽

Propionic Acid ◽

Structural Parameters ◽

Choline Chloride ◽

Self Diffusion ◽

Phenyl Propionic Acid ◽

Donor And Acceptor ◽

Experimental Values ◽

Self Diffusion Coefficient

AbstractDeep eutectic solvents (DESs) have received much attention in modern green chemistry as inexpensive and easy to handle analogous ionic liquids. This work employed molecular dynamics techniques to investigate the structure and dynamics of a DES system composed of choline chloride and phenyl propionic acid as a hydrogen bond donor and acceptor, respectively. Dynamical parameters such as mean square displacement, liquid phase self-diffusion coefficient and viscosity are calculated at the pressure of 0.1 MPa and temperatures 293, 321 and 400 K. The system size effect on the self-diffusion coefficient of DES species was also examined. Structural parameters such as liquid phase densities, hydrogen bonds, molecular dipole moment of species, and radial and spatial distribution functions (RDF and SDF) were investigated. The viscosity of the studied system was compared with the experimental values recently reported in the literature. A good agreement was observed between simulated and experimental values. The electrostatic and van der Waals nonbonding interaction energies between species were also evaluated and interpreted in terms of temperature. These investigations could play a vital role in the future development of these designer solvents.

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