Stimuli-reponsive polymers and their bioconjugates

Future perspectives and recent advances in stimuli-responsive materials

Interest in thermoresponsive polymers has steadily grown over many decades, and a great deal of work has been dedicated to developing temperature sensitive macromolecules that can be crafted into new smart materials. However, the overwhelming majority of previously reported temperature-responsive polymers are based on poly(N-isopropylacrylamide) (PNIPAM), despite the fact that a wide range of other thermoresponsive polymers have demonstrated similar promise for the preparation of adaptive materials. Herein, we aim to highlight recent results that involve thermoresponsive systems that have not yet been as fully considered. Many of these (co)polymers represent clear opportunities for advancements in emerging biomedical and materials fields due to their increased biocompatibility and tuneable response. By highlighting recent examples of newly developed thermoresponsive polymer systems, we hope to promote the development of new generations of smart materials.

New directions in thermoresponsive polymers.

As a new class of high-strength hydrogels, we designed a tetra-PEG gel by combining two symmetrical tetrahedron-like macromonomers of the same size. Because the nanostructural unit of the gel network was defined by the length of the tetrahedral PEG arm, the gel had a homogeneous structure and resultant high mechanical strength comparable to that of native articular cartilage. Furthermore, since the gel was formed by mixing two biocompatible macromonomer solutions, the gelation reaction itself and the resultant gel were also biocompatible. The breaking strength had local maxima at the overlap concentration of the macromonomers (C*) and at 2C*. Dynamic light scattering measurement indicated the near absence of inhomogeneities in the network at C*. Thus, we successfully designed and fabricated a high-strength hydrogel by controlling the homogeneity of network structure for the first time, which will lead to multiplied effects, i.e., contributing to the understanding of ideal networks, providing a universal s...

Design and Fabrication of a High-Strength Hydrogel with Ideally Homogeneous Network Structure from Tetrahedron-like Macromonomers

In situ gelling stimuli-sensitive block copolymer hydrogels for drug delivery.

Electric field sensitive neutral polymer gels

The combination of polymers with nanomaterials displays novel and often enhanced properties compared to the traditional materials. They can open up possibilities for new technological applications. The magnetic polymer gel represents a new type of composites consisting of small magnetic particles, usually from the nanometer range to the micron range, dispersed in a highly elastic polymeric gel matrix. Combination of magnetic and elastic properties leads to a number of striking phenomena that are exhibited in response to impressed magnetic fields. Giant deformational effects, high elasticity, anisotropic properties, temporary reinforcement and quick response to magnetic field open new opportunities for using such materials for various applications.

Smart Nanocomposite Polymer Gels

Novel gel actuator containing TiO2 particles operated under static electric field

Polymer gels are unique smart materials in the sense that they can respond to many different stimuli. In this paper we report how poly(N-isopropylacrylamide) (abbreviated as PNIPA) and other polymer hydrogels can be used to construct an intelligent gel-glass which can moderate the amount of light and radiated heat. This environmental sensitive glass, which is a smart hydrogel layer placed between two glass or plastic sheets, becomes opaque when the temperature exceeds a critical value. It becomes transparent again if it is cooled down. The adaptive properties of gel-glasses make them a promising materials to protect from strong sunlight and heat radiation. Copyright © 2001 John Wiley & Sons, Ltd.

József Fehér

Papers

Electric field sensitive neutral polymer gels

Smart Nanocomposite Polymer Gels

Novel gel actuator containing TiO2 particles operated under static electric field

Smart gel–glass based on the responsive properties of polymer gels

Bending deformation of neutral polymer gels induced by electric fields