The microscopic distribution of hydrophilic polymers in interpenetrating polymer networks (IPNs) of medical grade silicone. (14th May 2021)

• Record Type: Journal Article
• Authors: Smith, Gregory N.; Brok, Erik; Schmiele, Martin; Mortensen, Kell; Bouwman, Wim G.; Duif, Chris P.; Hassenkam, Tue; Alm, Martin; Thomsen, Peter; Arleth, Lise
• Is Part Of: Polymer. Volume 224(2021)
• Publication Date: 2021-05-14
• Subjects: Interpenetrating polymer network -- Neutron scattering -- Atomic force microscopy; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2021.123671
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: By introducing hydrophilic polymers into silicone medical devices, highly beneficial biomedical properties can be realized. An established solution to introduce hydrophilic polymers is to form an interpenetrating polymer network (IPN) by performing the hydrogel synthesis in the presence of silicone swollen in supercritical carbon dioxide. The precise distribution of the two polymers is not known, and determining this is the goal of this study. Neutron scattering and microscopy were used to determine the distribution of the hydrophilic guest polymer. Atomic force microscopy revealed that the important length scale on the surface of these materials is 10–100 nm, and spin-echo small-angle neutron scattering (SESANS) on IPNs submerged in D2 O revealed structures of the same scale within the interior and enabled quantification of their size. SESANS with hydration by D2 O proved to be the only scattering technique that could determine the structure of the bulk of these types of materials, and it should be used as an important tool for characterizing polymer medical devices. Graphical abstract: Image 1 Highlights: Swelling IPNs with D2 O introduces contrast for neutron scattering experiments. Spin-echo small-angle neutron scattering (SESANS) can resolve IPN structure. The different regions in IPNs are several hundred nm in diameter.