| Recently, the research interest for bone repairing materials increasingly focus on the polymer-based composites. Polyether ether ketone is a kind of high performance engineering plastics which has the strong resistance to hydrolysis, excellent chemical stability to the antibacterial treatment under the strong ultraviolet irradiation, as well as good biocompatibility. However, they are reported with poor bioactivity, this largely limited their application in the fields of hard tissue repair and replacement. The PEEK/HA composites turn into the most promising research direction in the field of bone repair due to that they possess both the excellent chemical stability, mechanics of PEEK matrix and the excellent bioactivity of HA. Despite of many research achievements about PEEK and ?m-HA or n-HA biocomposites, there still exits a big problem that the surface binding between them is so weak which leads a poor mechanical behavior of the PEEK/HA composites. So it is critical to change the surface properties of these two materials for improving their binding strength.In this work, the phosphate group was introduced to the main chain of PEEK through chemical modification and its surface property was changed. Due to the strong bonding force by the phosphate groups of the n-HA and the modified PEEK matrix, the interfacial adhesion between them was strengthen. In addition, nano-hydroxyapatite was modified in order to improve its agglomeration effect in the polymer matrix. After that, n-HA and PPEEK-A composites was prepared by solution casting technique, then its performance was characterized and analyzed. Several parts as follows was performed:1. The synthesis of phosphonated polyetheretherketone was performed by a post-phosphonation method via chloromethylation of the polyetheretherketone backbone followed by phosphonation utilizing the Michaels–Arbuzov reaction, then the modified PEEK in ester form were hydrolyzed to the corresponding phosphonic acid by refluxing in aqueous hydrochloric acid. The modified PEEK were characterized by nuclear magnetic resonance, infrared spectroscopy, differential scanning calorimetry and thermal gravity analysis. Different degree of phosphonation from 20% to 100% was achieved by controlling the reaction condition which is necessary to find the best DP for the solution casting.2. Nanometer-size needle-like hydroxyapatite with length of 50-100 nm and width of 8-10 nm was prepared from Ca(NO3)2·4H2O and(NH4)2HPO4 by wet co-precipitation method. The Fourier transform infrared spectroscopy(FTIR), the X-ray diffraction(XRD) were used to study the structural evolution, Laser diffraction particle size analyzers and TEM were used to estimate the particle size of the power and observe the morphology and agglomeration state of the powder. Results show that n-HA was successfully produced, while we found it apparent that ultra fine particles of HA aggregate into large clusters, it was improved apparently after dispersed by 4wt.% polyethyleneglycol and modified through chemical modification by KH550.3. Different ratio of PPEEK-A/n-HA mixture solution was achieved by dissolving the PPEEK-A in NMP and adding different mass fraction of modified nano hydroxyapatite to the polymer solution, then the expected shape of composites was obtained by solvent casting technique. The specimens were characterized by SEM, TGA and universal testing machine. The results showed that the composites own porous structure with n-HA particle in the hole and combine with the polymer matrix closely; The hydrogen between the two materials contribute to the improvement of the glass-transition temperature with the HA content increasing. The tensile strength of the composites improving with the increasing of HA content before the HA ratio was 9%, while decreasing with the increasing of HA content increasing after 9%. The tensile strength was improved through comparing with the PEEK/n-HA composites reported by the literature, the hydrogen between the PPEEK-A and n-HA may contribute to this phenomenon. |
PDF Full Text Request