“…Thus, we can say that surface treatment of BN particle with silane coupling agent reduces its crystallinity degree. Similar result was also observed by Cisneros Pineda et al . They found that the silanization process rendered hydroxyapatite with lower crystallinity compared to untreated hydroxyapatite.…”
This research aims at improving barrier properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, by incorporating boron nitride particles (BNPs) via melt compounding. To meet this objective, PHBV nanocomposite samples containing different BNPs were prepared and the effects of BN loading and silane surface modifier on the barrier properties of PHBV nanocomposites were investigated. For all the nanocomposite samples, the permeability is decreased in comparison to the neat PHBV due to both the presence of BN particles and a higher crystallinity. The results demonstrate that barrier properties of the composites were found to increase more for the silanized flake type BN (OSFBN) compared to silanized hexagonal disk type BN (OSBN). The best barrier properties are obtained for the nanocomposite sample containing 2 wt% OSFBN, for which a reduction of oxygen permeability up to 36% was observed in comparison to the neat PHBV. Silane-treated BN nanoparticles yielded nanocomposites characterized by good barrier performance and fine BN dispersion, as shown by SEM investigations. The phenomenological gas permeation models were employed to evaluate the effect of BN particles on oxygen transmission properties. The best approach was found for the relative permeation by using Cussler and Lape models. POLYM. COMPOS., 00:000-000, FIG. 1. SEM micrograph of boron nitride particles: untreated BN (a), treated OSBN (b), untreated FBN (c), treated OSFBN (d).
“…Thus, we can say that surface treatment of BN particle with silane coupling agent reduces its crystallinity degree. Similar result was also observed by Cisneros Pineda et al . They found that the silanization process rendered hydroxyapatite with lower crystallinity compared to untreated hydroxyapatite.…”
This research aims at improving barrier properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, by incorporating boron nitride particles (BNPs) via melt compounding. To meet this objective, PHBV nanocomposite samples containing different BNPs were prepared and the effects of BN loading and silane surface modifier on the barrier properties of PHBV nanocomposites were investigated. For all the nanocomposite samples, the permeability is decreased in comparison to the neat PHBV due to both the presence of BN particles and a higher crystallinity. The results demonstrate that barrier properties of the composites were found to increase more for the silanized flake type BN (OSFBN) compared to silanized hexagonal disk type BN (OSBN). The best barrier properties are obtained for the nanocomposite sample containing 2 wt% OSFBN, for which a reduction of oxygen permeability up to 36% was observed in comparison to the neat PHBV. Silane-treated BN nanoparticles yielded nanocomposites characterized by good barrier performance and fine BN dispersion, as shown by SEM investigations. The phenomenological gas permeation models were employed to evaluate the effect of BN particles on oxygen transmission properties. The best approach was found for the relative permeation by using Cussler and Lape models. POLYM. COMPOS., 00:000-000, FIG. 1. SEM micrograph of boron nitride particles: untreated BN (a), treated OSBN (b), untreated FBN (c), treated OSFBN (d).
“…For example, the band at 1,566 cm −1 for MAh-nHA is representative of the carboxylate group formed during the ionic side reaction between methacrylic acid and calcium ions at the nHA surface (Cisneros-Pineda et al, 2014); this suggests a large amount of electrostatic interactions at the nHA surface. In addition, C=O and C=C bond stretches are apparent for each methacrylate reagent; these are indicative of at least the presence of these reagents at the nHA surface (Arcís et al, 2002;Cisneros-Pineda et al, 2014). For MAh-nHA, the C=O peak occurs at 1,696 cm −1 , while the C=C peak occurs at 1,634 cm −1 .…”
Section: Resultsmentioning
confidence: 92%
“…In this paper, we first present the results of direct functionalization of non-stoichiometric HA nanoparticle (nHA) surfaces using two different methacrylates under mild conditions-methacrylic anhydride (MAh), and glycidyl methacrylate (GMA)-and subsequently report changes to nHA particle dispersion in different media, before adding the nHA to methacrylated gelatin (GelMA) and assessing the composite stiffness and swelling in a proof-of-concept investigation. A surface functionalization control for this study is the well-studied silanated-nHA (Si-nHA), achieved using methacryloxypropyltrimethoxysilane (MPTS) (Cisneros-Pineda et al, 2014;Lung et al, 2016). Unfortunately, typical silanization reactions involve harsh reaction conditions (e.g., acidic pH), and a high risk of forming unstable multilayers (Liu et al, 2001;Halvorson et al, 2003;Amdjadi et al, 2017), neither of which is ideal toward the development of an nHAbased bone-mimetic composite.…”
Modification of the inorganic particle surface is one approach toward enhancing the mechanical and swelling properties of a bone-inspired composite. In this study we sought to manipulate the surface of non-stoichiometric nHA particles by utilizing a gentler methacrylation approach with two different methacrylates-methacrylic anhydride (MAh) and glycidyl methacrylate (GMA). While silanization of nHA (Si-nHA) is a recognized functionalization approach, one notable disadvantage is the need for relatively harsh reaction conditions. Here, ATR-FTIR and liquid state 13 C-NMR provided evidence for a stronger affinity of the nHA surface for methacrylic anhydride compared to glycidyl methacrylate under the same reaction conditions; fewer GMA molecules reacted with the nHA surface. However, the affinity of MAh is more electrostatic in nature, whereas GMA attachment involves some covalent bond formation. In addition, while in water, there was no detectable dependence of particle settling on methacrylate choice, in ethanol, native nHA and nHA methacrylated with GMA each had detectably greater stability in suspension than the other sample groups. Lastly, the addition of GMA-nHA detectably increased the dynamic stiffness and did not impact the swelling in 37 • C water of a GelMA-based composite compared to that observed upon adding native nHA. Overall, the GMA-based methacrylation approach was found to be a viable alternative to silanization and offers possibilities for future fabrication of bone-inspired composites.
“…11,25 Other peaks associated to the formation of apatitic layer or HA on these composites were observed at 25.9°, 26°, 32.7°, 34.6°, 36.7°, 49.6°, and 50.4° as reported in other studies. 12,17,24–27 Figure 11.XRD patterns of composites conditioned at 3, 7, and 10 days in SBF at 37℃; SPU-G (a), SPU-G 5% nBG (b), SPU-G 15% nBG (c), and SPU-G 25% nBG (d).…”
Composites of glutamine-based segmented polyurethanes with 5 to 25 wt.% bioactive glass nanoparticles were prepared, characterized, and their mineralization potential was evaluated in simulated body fluid. Biocompatibility with dental pulp stem cells was assessed by MTS to an extended range of compositions (1 to 25 wt.% of bioactive glass nanoparticles). Physicochemical characterization showed that composites retained many of the matrix properties, i.e. those corresponding to semicrystalline elastomeric polymers as they exhibited a glass transition temperature (Tg) between -41 and -36℃ and a melting temperature (Tm) between 46 and 49℃ in agreement with X-ray reflections at 23.6° and 21.3°. However, with bioactive glass nanoparticles addition, tensile strength and strain were reduced from 22.2 to 12.2 MPa and 667.2 to 457.8%, respectively with 25 wt.% of bioactive glass nanoparticles. Although Fourier transform infrared spectroscopy did not show evidence of mineralization after conditioning of these composites in simulated body fluid, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray microanalysis showed the formation of an apatite layer on the surface which increased with higher bioactive glass concentrations and longer conditioning time. Dental pulp stem cells proliferation at day 5 was improved in bioactive glass nanoparticles composites containing lower amounts of the filler (1-2.5 wt.%) but it was compromised at day 9 in composites containing high contents of nBG (5, 15, 25 wt.%). However, Runx2 gene expression was particularly upregulated for the dental pulp stem cells cultured with composites loaded with 15 and 25 wt.% of bioactive glass nanoparticles. In conclusion, low content bioactive glass nanoparticles and segmented polyurethanes composites deserve further investigation for applications such as guided bone regeneration membranes, where osteoconductivity is desirable but not a demanding mechanical performance.
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