Preparation, Characterization, and Bioactivity Evaluation of Polyoxymethylene Copolymer/Nanohydroxyapatite-g-Poly(ε-caprolactone) Composites

Abstract

In this work, nanohydroxyapatite (HAp) was functionalized with poly(ε-caprolactone) (PCL), using 1,6-hexamethylene diisocyanate (HDI) as a coupling agent, and then incorporated into the polyoxymethylene copolymer (POM) matrix using the extrusion technique. The obtained POM/HAp-g-PCL composites were investigated using FTIR, DSC, TOPEM DSC, and TG methods. Mechanical properties were studied using destructive and non-destructive ultrasonic methods, wettability, and POM crystallization kinetics in the presence of HAp-g-PCL. Moreover, preliminary bioactivity evaluation of the POM/HAp-g-PCL composites was performed using the Kokubo method. It was found that the introduction of HAp-g-PCL to the POM matrix has a limited effect on the phase transitions of POM as well as on its degree of crystallinity. Importantly, HAp grafted with PCL caused a significant increase in the thermal stability of the POM, from 292 °C for pristine POM to 333 °C for POM modified with 2.5% HAp-g-PCL. If unmodified HAp was used, a distinct decrease in the thermal stability of the POM was observed. Crystallization kinetic studies confirmed that HAp-g-PCL, in small amounts, can act as a nucleating agent for the POM crystallization process. Moreover, incorporation of HAp-g-PCL, although slightly decreasing the mechanical properties of POM composites, improved the crucial parameter in biomedical applications, namely the in vitro bioactivity.

Effect of non-thermal sulphur hexafluoride cold plasma modification on surface properties of polyoxymethylene

“…On the non-modi ed POM surface (Fig. 2A) the WCA value is equal to 78.2 degrees, which is consistent with the literature results [40][41][42]. Figure 2B, 2C and 2D show the samples from each series with the largest obtained effect.…”

Effect of Non‐Thermal Sulfur Hexafluoride Cold Plasma Modification on Surface Properties of Polyoxymethylene

“…Typical examples of the changes in the wettability induced by the plasma modification are illustrated in Figure 2. On the non‐modified POM surface (Figure 2A) the WCA value is equal to 78.2 degrees, which is consistent with the literature results [40–42] . Figure 2B, 2 C and 2D show the samples from each series with the largest obtained effect.…”

“…On the non-modified POM surface (Figure 2A) the WCA value is equal to 78.2 degrees, which is consistent with the literature results. [40][41][42] Figure 2B, 2 C and 2D show the samples from each series with the largest obtained effect. It can be observed that the contact angle values increased more than twice.…”

Use of synthetic wollastonite nanofibers in enhancing mechanical, thermal, and flammability properties of polyoxymethylene nanocomposites

“…[44] The fingerprint region (500-1500 cm À1 ) of IR spectrum in Figure 1 also clearly showed all the characteristic peaks of pure POM. [45][46][47] The incorporation of SWN into the POM nanocomposites did not influence the FTIR spectrum, which there was not any peak shifting, appearance of new peak or disappearance of old peak observed. This shows that there was no strong chemical interaction between SWN and POM chains during the melt extrusion, thus it is suggested that physical interaction was mandatory in altering the properties of POM/SWN nanocomposites.…”