We investigated the structural properties of dynamic micelles arising from the self-assembly of the multiresponsive pentablock quaterpolymer P(nBuMA 8 -co-TEGMA 8 )-b-PDMAEMA 50 -b-PEG 46 -b-PDMAEMA 50 -b-P-(nBuMA 8 -co-TEGMA 8 ) (nBuMA, TEGMA, DMAEMA, and EG are n-butyl methacrylate, tri(ethylene glycol) methyl ether methacrylate, 2-(dimethylamino)ethyl methacrylate, and ethylene glycol, respectively) in aqueous solution using a combination of scattering methods. In this multisegmented polymer, a pH-responsive BAB triblock copolymer from the weak cationic polyelectrolyte PDMAEMA and the hydrophilic PEG is end-capped by two blocks comprising random sequences of thermoresponsive TEGMA units and hydrophobic nBuMA units. Dynamic light scattering revealed the existence of single micelles and small clusters in dilute aqueous solution. The hydrodynamic radius of the micelles depends strongly on pH and temperature. The inner structure of the micelles was investigated by small-angle X-ray scattering, small-angle neutron scattering, and static light scattering, and micelles with a hydrophobic core containing a rather high fraction of water and a strongly swollen corona were found. The ratio of loops and dangling ends depends on temperature and pH.

This review summarizes work done on triply, or higher, interpenetrating polymer network materials prepared in order to widen the properties of double polymer network hydrogels (DN), doubly interpenetrating polymer networks with enhanced mechanical properties. The review will show that introduction of a third, or fourth, polymeric component in the DNs would further enhance the mechanical properties of the resulting materials, but may also introduce other useful functionalities, including electrical conductivity, low-friction coefficients, and (bio)degradability.

We present the preparation and study of the compressive mechanical and swelling properties of multiply interpenetrated, from double to quintuple (5-fold), polymeric hydrogels based on N,N-dimethylacrylamide (DMAAm) crosslinked with N,N′-methylenebis(acrylamide) (MBAAm), using five different monomer concentrations, from 1 to 5 M. Our results showed enhancement of the fracture stress, fracture energy density, and Young's modulus with network multiplicity and DMAAm monomer concentration. Fracture strain was found to substantially improve only when increasing the monomer concentration from 1 to 3 M and network multiplicity from 1 to 2. The best-performing multiple polymer hydrogel was the quintuple network prepared at 5 M DMAAm concentrations, which exhibited a record fracture stress of 51 MPa, a fracture strain of 88%, a fracture energy density of 5.5 MJ m −3 , and a Young's modulus of 2.1 MPa. Normalized values of the fracture stress and fracture energy density calculated by multiplication of the corresponding original values by the aqueous swelling degrees also increased with network multiplicity and monomer concentration, suggesting a net gain in mechanical property enhancement, primarily originating from network multiplicity. Combined analysis of the swelling and Young's modulus measurements on the multiply interpenetrated polymeric hydrogels allowed the calculation of the concentration of the elastically ef fective polymer chains in the bulk, which was independent of monomer concentration but increased linearly with network multiplicity, suggesting a corresponding increase in the concentration of trapped entanglements and/or strain hardening.

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Tunable electrostatic interactions in thin films from (C-co-D)-b-B-b-A-b-B-b-(C-co-D)-type pentablock quaterpolymers featuring hydrophobic end blocks as well as pH-responsive and hydrophilic midblocks allow controlling their morphology both by the choice of the pH value during film preparation and the solvent polarity during solvent vapor swelling. The morphological changes were characterized using grazing-incidence small-angle X-ray scattering, and the data analysis was carried out on the basis of simulations of two-dimensional scattering patterns. Dry films prepared at low and at high pH values feature either weakly ordered spheres or totally lack order, respectively. Swelling the former films in water vapor triggers an order-to-disorder transition, which is reversed upon drying, whereas films prepared at a high pH value remain disordered. Upon swelling in toluene vapor, the morphology of films prepared at a low pH value is stable, whereas the ones prepared at a high pH value microphase-separate into a spherical morphology.