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A macroporous monolithic material based on an N-hydroxyphthalimide ester of acrylic acid-co-glycidyl methacrylate-co-ethylene dimethacrylate terpolymer was synthesized by photoinitiated free-radical polymerization. Several porogenic solvents, such as cyclohexanol, dodecanol, and poly(ethylene glycol)s, were tested to obtain the monolithic material with an optimal pore size allowing unrestricted penetration of large molecule (proteins) into a three-dimensional porous space. The new monolithic material was covalently bound to an inert surface (glass) directly in the polymerization step, and it was suggested as a solid matrix for the development of new types of three-dimensional protein microarrays (biochips). A demonstration of the potential of the suggested microarray platform as well as optimization of microarray performance conditions was realized with a model mouse immunoglobulin G/goat anti-mouse immunoglobulin G affinity pair.

Two types of high-strength composite hydrogels possessing the structure of interpenetrating polymer networks were synthesized via free-radical polymerization of acrylamide carried out straight within the matrix of plant or bacterial cellulose swollen in the reactive solution. The mechanical behavior of synthesized hydrogels subjected to the action of compressive deformations with different amplitude values was studied. The analysis of the stress-strain curves of compression tests of the hydrogels of both types obtained in different test conditions demonstrates the substantial difference in their mechanical behavior. Both the plant cellulose-based and bacterial cellulose-based hydrogels withstand successfully the compression with the amplitude up to 80 %, but the bacterial cellulose-based compositions demonstrate in the multiple compression tests the substantial decrease of the mechanical stiffness caused by the action of compressions. This effect takes place straightly during the multiple cyclic compression tests or in the course of relaxation of previously compressed samples in water in unloaded state during 2-3 days after the first compressive tests. Being subjected to the action of the extremely sever compression (up to 80 %) the bacterial cellulose-based hydrogel varies greatly its mechanical behavior: during the subsequent compressions the stiffness of the material keeps extremely small (as compared to that registered in the first compression) up to the deformations as high as 50-60 % with the dramatic increase of the stiffness during the further loading. This unusual effect can be explained by the deep reorganization of the intermolecular structure of the material with the stress-induced reorientation of cellulose micro-fibrils, fragmentation and disintegration of the interpenetrating networks structure with the breaking of the covalent bonds in the matrix polymer. Submicron-and micron-scale specific features of structures of composite hydrogels of both types were studied by cryo-scanning electron microscopy to explain the peculiarities of observed mechanical effects.

Submicron-and micron-scale structures of composite hydrogels based on bacterial cellulose (BC) and polyacrylamide were studied by spin-echo small-angle neutron scattering (SESANS) and cryo-scanning electron microscopy (cryo-SEM). These hydrogels possessing the structure of interpenetrating polymer network were synthesized via free-radical polymerization of acrylamide carried out in the pellicle of BC swollen in the reaction solution. No neutron scattering was observed for the samples swollen in heavy water to the equilibrium state, but the SESANS signal appeared when TbCl 3 salt was added to the solvent. It is the unusual effect, which may be very helpful for SESANS studying of other hydrogel systems. The SESANS dependences obtained for these samples revealed the anisotropy of mesostructure for the hydrogels under investigation. Density inhomogeneities on the characteristic scale of 11.5 ± 0.5 µm were detected in one fixed orientation of the sample, i.e. with the growth plane of BC parallel to the plane formed by the neutron beam and the spin-echo length. The uniaxial anisotropy revealed agrees with a recently proposed model, which attributes this behavior to the existence of tunnel-like oriented structures inside BC. The evidence of such type of mesostructure anisotropy of BC and BC-PAAM hydrogels was obtained by using the cryo-SEM method.

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