Polyacrylic Acid Polyacrylamide Research Articles

Tribological properties of hierarchical structure artificial joints with poly acrylic acid (AA) - poly acrylamide (AAm) hydrogel and Ti6Al4V substrate

Natural joints have the hierarchical structure of bone and cartilage, providing excellent lubrication and load-carrying capacity. In our research, the hierarchical structure artificial joints of Poly Acrylic Acid (PAA)- Poly Acrylamide (PAAm) hydrogel coating and Ti6Al4V substrate were formed using a simple yet versatile method by mimicking the hierarchical structure of natural joints. The efficient lubrication at friction interfaces was achieved. The composition and microstructure were confirmed by Fourier-transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM). The hydrogel coatings were successfully prepared on the surface of Ti6Al4V substrate through the adsorption of the charged group. This hierarchical structure material exhibits the lower dynamic friction, approximately 0.085, which is much lower than bare Ti6Al4V, about 0.429. The wear on the surfaces after the tribological experiment is super-shallow and has no significant fracture area around the scratch. The PAA-PAAm hydrogel has a more uniform and compact cross-linked network porous structure, and the porous size is much smaller than PAA hydrogel. The cross-linked network porous structure is the main factor accounting for the low dynamic friction. This hierarchical structure of soft and hard improve the load-carrying ability and has the potential uses in artificial joints.

Improved biotribological properties of polyetheretherketone composites for artificial joints with a ‘soft-on-hard’ structure and brushlike molecules

On the purpose of improving the biotribological performance of polyetheretherketone (PEEK) for artificial joints, mimicking the ‘soft-on-hard’ contact mode of ‘cartilage-subchondral bone’ construction as well as the special brushlike structure of natural articular cartilage, a ‘soft-on-hard’ structure with a poly acrylic acid-poly acrylamide (PAA-PAAm) hydrogel layer connected onto a PEEK substrate was fabricated. Meanwhile, methacrylated sodium alginate (SAGMA) was introduced into the hydrogel layer to form molecular brushes. Compared to the friction coefficient of a pristine PEEK (0.22), that of the PEEK-hydrogel-molecular brush structure was significantly lower (0.02) benefiting from the synergistic effect of biphasic lubrication and boundary lubrication. This work develops a useful method to effectively improve the biotribological properties of artificial joints.

A Novel Anisotropic Hydrogel with Integrated Self-Deformation and Controllable Shape Memory Effect.

Although shape memory polymers have been highlighted widely and developed rapidly, it is still a challenging task to realize complex temporary shapes automatically in practical applications. Herein, a novel shape memory hydrogel with the ability of self-deformation is presented. Through constructing an anisotropic poly(acrylic acid)-polyacrylamide (PAAc-PAAm) structure, the obtained hydrogel exhibits stable self-deformation behavior in response to pH stimulus, and the shapes that formed automatically can be fixed by the coordination between carboxylic groups and Fe3+ ; therefore, self-deformation and shape memory behaviors are integrated in one system. Moreover, the magnitude of auto-deformation and shape memory could be adjusted with the concentration of corresponding ions, leading to programmable shape memory and shape recovery processes.

Morphology control of ZnO nanostructures

Highly crystalline zinc oxide (ZnO) nanomaterials are synthesized using a seeded growth sol-gel method. In order to control the morphology and the dimensionality of ZnO crystals, a double hydrophilic block copolymer, the Polyacrylic acid-Polyacrylamide (PAA-PAM), was introduced during the growth step. It was shown, first, that depending on the amount of PAA-PAM copolymer, different morphologies of ZnO particles precipitated from homogeneous solutions were obtained, such as ZnO nanostructured spheres or flat hexagonal crystals. Secondly, the dimensionality of ZnO objects grown from seeds on a substrate could be tuned by varying the amount of copolymer leading to ZnO films with variable characteristics. Thus, systematic studies were done in order to investigate the influence of copolymer addition on ZnO nanomaterial morphologies and then explain the mechanisms of the morphological and dimensional modifications.

Morphology Control of ZnO Nanomaterials using Double Hydrophilic Block Copolymers

AbstractHighly crystalline zinc oxide (ZnO) nanomaterials are synthesized using a seeded growth sol-gel method. In order to control the morphology and the organization of the ZnO nanomaterials, a double hydrophilic block copolymer has been introduced during the seeded growth synthesis: the Polyacrylic acid-Polyacrylamide (PAA-PAM). Depending on the amount of PAA-PAM copolymers, different morphologies were obtained, such as ZnO nanostructured spheres or flat hexagonal crystals. Thus, systematic studies have been done to investigate the influence of the copolymer addition on ZnO nanomaterial morphologies and explain the mechanisms of the morphological modifications.