Synthesis of Temperature-Responsive Organic-Inorganic Hybrid Hydrogel by Free-Radical Polymerization of Methacrylamide Using Water-Soluble Rigid Polysiloxane Having Acryamido Side-Chains as a Cross-linking Agent

Abstract

Polymeric hydrogels are three-dimensional polymer networks containing a large amount of water, which have been used in a variety of applications, e.g., soft contact lenses, absorbents, and cosmetics, due to their high water contents and soft touchness. 1 In particular, a considerable number of researches have been focused on stimuli-responsive hydrogels, in which they can change their properties in response to environmental stimuli such as pH, temperature, ionic strength, and electric field.2,3 The stimuli-responsive hydrogels have been investigated for many biomedical and pharmaceutical applications, e.g., drug delivery system (DDS). 2,3 As familiar examples, it has been reported that the hydrogels composed of poly(N-isopropylacrylamide), poly(N,N-diethylacrylamide), and poly-(ethylene oxide)-poly(propylene oxide) block copolymer have exhibited temperature-response. 2-6On the other hand, the hydrogels had some serious disadvantages such as brittleness and lack of mechanical toughness. So far, to solve these disadvantages of the hydrogels, synthesis of organic-inorganic nanocomposite (hybrid) hydrogels have been reported, 7,8 which are composed of organic polymer as a mainchain and inorganic dispersed clay as a cross-linking agent. A clay has two-dimensional rigid sheet structure forming regular higher-ordered structure (lamellar phase) and can disperse in the water. These properties of the clay would contribute to the superior characteristics such as high mechanical strength, elongation, and transparency of the hydrogels. However, since other inorganic materials, which have rigid structure and dispersion behavior, have hardly ever been known, the variety of the organic-inorganic hybrid hydrogels has been restricted. The availability of new inorganic cross-linking agents promisingly introduces additional development of new functions and applications of novel high-performance hybrid hydrogels.So far, water-soluble polysiloxanes having alkylammonium groups were synthesized by the sol-gel reaction of aminoalkyltrialkoxysilane in strong acid aqueous solution.9,10 In the solid state, these polysiloxanes were stacked to form the hexagonal phase, implying their rigid-rod structures. The polysiloxanes have inspired us to use them for the development of a new hybrid hydrogel, because of their comparable water-dispersibility and rigidity to those of a clay. Accordingly, we prepared a polysiloxane-based multifunctional cross-linking agent for a new organic-inorganic hybrid hydrogel.11 The cross-linking agent was synthesized by reaction of the rigid polysiloxane with acryloyl chloride. Then, the organic-inorgnic hybrid hydrogels were obtained by free-radical polymerization of an acrylamide (AAm) monomer using the cross-linking agent. The compressive properties of the obtained hydrogels were more superior than those of conventional poly(AAm) (PAAm) hydrogels. Based on the backgrounds described above, development of novel temperature-responsive organic-inorganic hybrid hydrogels would be a promising topic in the material rese...

Study of dual responsive poly[(maleilated dextran)‐graft‐(N‐isopropylacrylamide)] hydrogel nanoparticles: preparation, characterization and biological evaluation

“…Hydrogels are defined as lightly crosslinked, three‐dimensional hydrophilic polymer networks capable of absorbing large volumes of water while remaining insoluble in water. Those whose behaviors change in response to environmental signals, such as temperature, pH, ionic strength, electric field and magnetic field, are called stimuli‐sensitive hydrogels 1–6. Poly( N ‐isopropylacrylamide) (PNIPAAm), which exhibits a distinct phase transition at a lower critical solution temperature (LCST) between 30 and 35 °C, is among the most reported temperature‐sensitive hydrogels.…”

Self-assembled Monolayers and Nanocomposite Hydrogels of Functional Nanomaterials for Tissue Engineering Applications

“…A wide range of NMs and polymers have been used for the generation of NC hydrogels with superior properties and tailored functionalities. In particular, silica based NMs such as clays (e.g., hectorite, montmorillonite), silica NPs, other minerals such as polyhedral oligomeric silsesquioxane, polysiloxane, fibrillar attapulgite, and hydrotalcite combined with polymers such as poly( N ‐isopropylacryamide) or poly( N , N ‐dimethylacrylamide), poyl(acryl amide), poly(vinyl alcohol), poyl(ethylene oxide) (PEO), etc. have been widely used for mechanically strong and cell‐compatible NC hydrogels preparation.…”

Synthesis, Surface and Spreading Properties of Lactobionamide-Grafted Amphiphilic Glycopolysiloxanes

“…[13][14][15][16][17] But it involves the time and material consuming steps of protecting and deprotecting the hydroxyl groups of the carbohydrate in order to avoid side reactions in these processes. To overcome the problem, another simpler method has been developed by our group and others [18][19][20][21][22][23] : glycopolysiloxane can be synthesized by forming amide bonds of amino functional polysiloxane with lactones (or acids).…”