The Relationship between the Hydrophilicity and Surface Chemical Composition Microphase Separation Structure of Multicomponent Silicone Hydrogels

Abstract

Three series of multicomponent silicone hydrogels were prepared by the copolymerization of two hydrophobic silicon monomers bis(trimethylsilyloxy) methylsilylpropyl glycerol methacrylate (SiMA) and tris(trimethylsiloxy) 3-methacryloxypropylsilane (TRIS) with three hydrophilic monomers. The surface hydrophilicity of the silicone hydrogels was characterized by contact angle measurements, and an interesting phenomenon was found that the silicone hydrogels made from less hydrophobic monomer SiMA possess more hydrophobic surfaces than those made from TRIS. The surface properties such as morphology and elemental composition of the silicone hydrogels were explored by scanning electron microscopy (SEM) imaging and energy dispersive spectrometry (EDS) analysis, and their relationships with the surface hydrophilicity were investigated in details. The results show neither the surface morphology nor the elemental composition has obvious impact on the surface hydrophilicity. Atomic force microscopy (AFM) imaging revealed that SiMA hydrogel had a more significant phase separation structure, which also made its surface uneven: a lot of tiny holes were observed on the surface. This surface phase separation structure made SiMA hydrogel more difficult to be wetted by water or PBS buffer, i.e., more hydrophobic than TRIS hydrogel. On the basis of these results, we propose that the phase separation structure as well as the nature of silicon monomers might be the fundamental reasons of surface hydrophilicity. These results could help to design a silicone hydrogel with better surface properties and wider application.

Multifunctional sensors based on silicone hydrogel and their responses to solvents, pH and solution composition

“…The silicone hydrogels were prepared using the following method . The photoinitiator D‐1173 and crosslinker EGDMA were combined in a flask.…”

“…A great deal of research has focused on the preparation and properties of multifunctional silicone hydrogels . Some silicone hydrogels display an obvious change in volume in response to pH and solvent stimuli which can be observed by the naked eye .…”

The Ophthalmic Performance of Hydrogel Contact Lenses Loaded with Silicone Nanoparticles

“…Thus, the addition of SiNPs did little to change the wettability of these lenses. The slight increase may be attributed to a small quantity of hydrophobic PDMS (from SiNPs) exposed on the surface [23]. Figure 12 shows that the FTIR spectra of HS-series lenses differed little as the contents of SiNPs increased from 0 wt% to 1.2 wt%.…”

“…However, this will decrease the oxygen permeability because of hydrophilic monomers. On the other hand, a higher PDMS content will enhance oxygen permeability but reduce the water uptake ability [11,22,23]. In silicone hydrogel contact lenses, water is a main factor to restrict the oxygen permeability [24][25][26].…”

Structure–property correlation of silicone hydrogels based on 3‐[tris(trimethylsilyloxy)silyl]propyl methacrylate monomer

“…found that the silicone phase of SiMA and TRIS was of granular and fibrous textures, respectively, and the latter contributed to the higher oxygen permeability. In another study, it was proposed that the hydrophilicity of silicone hydrogels made from silicone monomer TRIS is better than those made from SiMA, based on phase separation structure and the nature of silicone monomers. Momentive Performance Materials, a specialty silicones company, is placing tremendous efforts in the past several years to develop new generation materials for hydrogel articles to offer performance, process simplification, and comfort to customers…”