Morphology, crystallization, thermal, and mechanical properties of poly(vinylidene fluoride) films filled with different concentrations of polyhedral oligomeric silsesquioxane

POSS hybrid bioactive glass dental composite resin materials: Synthesis and analysis

INTRODUCTION

This study create a dental composite by hybirding polyhedral oligo-sesquioxide nano monomers and bioactive glass BG 45S5.

METHODS

Make an experimental composite resin material with a 60 % filler content overall by substituting 20 % of the filler with BG 45S5. The experimental resins are grouped and named P0, P2, P4, P6 and P8 based on the reactive nanomonomer methacrylic acid-based multifaceted oligomeric sesquisiloxane (POSS) added by 2 %-8 % in the resin matrix portion of each group. Utilize a universal testing machine to analyze and compare the mechanical properties of these, then perform Fourier infrared spectrum analysis, double bond conversion analysis, and scanning electron microscope analysis. Based on this, after soaking the experimental materials artificial saliva solution or lactic acid solution for a while, the pH changes of the solution, the release of Ca2+ and PO43- ions, and the precipitation of apatite on the resin material's surface were tested and analyzed. Cell viability tests were used to assess sample cell viability and quantify the cytotoxicity of biological cells. The independent sample t-test was used to examine the group comparisons, and a difference was considered statistically significant at P<0.05.

RESULTS

Outstanding mechanical and the double bond conversion are demonstrated by the nanocomposites when the POSS concentration hits 4 wt%. Agglomeration will cause the performance to deteriorate if the concentration beyond this threshold. In the P4 group, the double bond conversion, CS, and FS rose by a large margin, respectively, in comparison to the blank control group P0. Thankfully, the data demonstrate that adding POSS increases adhesive ability when compared to the blank group P0, however, there is no discernible difference between the other experimental groups. The acid neutralization capacity of the P4 group is essentially the same as that of the control group (P0). Ca2+ and PO43- ions are released in significant amounts following treatment with lactic acid solution, although this tendency is clearly less pronounced in artificial saliva. SEM and EDX data indicate that when the experimental resin is soaked in lactic acid solution and artificial saliva, apatite precipitation will happen on its surface. The results of the cell viability test indicated that there was no statistically significant difference between the experimental groups, and the viability of the cells increased after 24hours and 48 hours.

CONCLUSIONS

POSS was included into the composite resin along with 20% bioactive glass as a filler. When the proportion of POSS is less than 4%, the indices of composite resin materials rise in a dose-dependent way. When this value is surpassed, performance begins to deteriorate. The inclusion of POSS has no influence on the biological activity of the composites, which means that the hybrid composite resin is capable of acid neutralization, ion release, and apatite precipitation.

CLINICAL SIGNIFICANCE

The experimental composite resin can be used as an intelligent material in clinical treatment. It has the clinical application potential of preventing demineralization of tooth hard tissue, promoting remineralization, and improving edge sealing through apatite precipitation.

Luminescent and sustainable d10 coinage metal thiolate coordination polymers for high-temperature optical sensing

The d¹⁰ coinage metal coordination polymers (CPs) are known to display photophysical properties which can be tuned depending on the functionality of the ligand. Three new CPs made of d¹⁰ coinage metals and methyl thiosalicylate, [M(o-SPhCO₂Me)]_n (M = Cu, Ag, Au), are reported. They are all constructed from one-dimensional metal-sulfur networks, in which Cu and Ag are three-coordinated to sulfur atoms, whereas Au is only two-coordinated. It results that both Cu(I) and Ag(I) CPs show orange photoemission at room temperature, and the Au(I) one exhibits near-infrared emission at low temperatures. The intense orange-emissive Ag(I) CP and the blue-emissive coumarin 120 have been mixed in an organic matrix, the polyvinylidene fluoride (PVDF), to form a dual luminescent flexible composite film. This film, evaluated for thermometry, shows great sensitivity for temperatures up to 100°C, a temperature never reached with non-lanthanide-based CPs.

Kinetics of thermal degradation and lifetime study of poly(vinylidene fluoride) (PVDF) subjected to bioethanol fuel accelerated aging

PVDF was prepared by compression molding, and its phase content/structure was assessed by WAXD, DSC, and FTIR-ATR spectroscopy. Next, PVDF samples were aged in bioethanol fuel at 60 °C or annealed in the same temperature by 30 ─ 180 days. Then, the influence of aging/annealing on thermal stability, thermal degradation kinetics, and lifetime of the PVDF was investigated by thermogravimetric analysis (TGA/DTG), as well as the structure was again examined. The crystallinity of ~41% (from WAXD) or ~49% (from DSC) were identified for unaged PVDF, without significant changes after aging or annealing. This PVDF presented not only one phase, but a mixture of α-, β- and γ-phases, α- and β-phases with more highlighted vibrational bands. Thermal degradation kinetics was evaluated using the non-isothermal Ozawa-Flynn-Wall method. The activation energy (E _a ) of thermal degradation was calculated for conversion levels of α = 5 ─ 50% at constant heating rates (5, 10, 20, and 40 °C min^─1), α = 10% was fixed for lifetime estimation. The results indicated that temperature alone does not affect the material, but its combination with bioethanol reduced the onset temperature and E _a of primary thermal degradation. Additionally, the material lifetime decreased until about five decades (T _f = 25 °C and 90 days of exposition) due to the fluid effect after aging.

POSS Dental Nanocomposite Resin: Synthesis, Shrinkage, Double Bond Conversion, Hardness, and Resistance Properties

Nanocomposite dental resins with 0, 2, 5, and 10 wt % methacryl polyhedral oligomeric silsesquioxane (POSS) as filler in the resin matrix were prepared by a light curing method.The atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), nanoindentation, and nanoscratch tests were carried out to study the effect of POSS contents on the compatibility, double bond conversion, volumetric shrinkage, hardness, modulus, and resistance of the dental resins. POSS was very uniformly dispersed and showed a good compatibility with the matrix. The double bond conversion increased and the volume reduced with the addition of POSS. As the POSS addition increased, the mechanical properties increased initially. Small addition of POSS remarkably enhanced the hardness and scratch resistance of the resin matrix.

Influence of trifluoropropyl-POSS nanoparticles on the microstructure, rheological, thermal and thermomechanical properties of PLA

A comprehensive study was carried out on the influence of a new kind of POSS on different properties of PLA and correlation with the microstructure.

Reactive Molecular Dynamics Simulations on the Disintegration of PVDF, FP-POSS, and Their Composite during Atomic Oxygen Impact

Poly(vinylidene fluoride) (PVDF) is a kind of important piezoelectric polymer used in spacecraft industry. But the atomic oxygen (AO) is the most abundant element in the low Earth orbit (LEO) environment. AO collision degradation is an important issue in the application of PVDF on spacecrafts. To investigate the erosion behaviors of PVDF during AO impacts and how to improve the stability of PVDF against AO impacts, the temperature evolution, mass loss, and erosion yields of neat PVDF, neat polyhedral oligomeric silsesquioxanes compound (3,3,3-trifluoropropyl)8Si8O12 (FP-POSS) and the PVDF/FP-POSS composite under AO impacts, as well as some key disintegrated structures and separated chemical compositions, were researched using the molecular dynamics (MD) simulations and the reactive ReaxFF force field. The simulation erosion yield result of PVDF is very close to the experiment results, which shows our simulations are reliable. The results of the temperature evolution, mass loss, and erosion yield of three materials show that the antierosion performance of PVDF is not outstanding. However, incorporating FP-POSS into PVDF matrix enhances the stability of PVDF against AO impact greatly and reduces the temperature rise, mass loss, and the erosion yield of PVDF rapidly. A detailed analysis on the flight chemical compositions and key snapshots of the structures reveals that the erosion process on PVDF and PVDF/FP-POSS is continuous and should be derived from the same PVDF matrix in two materials. In contrast, the erosion process on FP-POSS is stepped. The erosion will not take place until the number of AO reaches a specific value. There is a barrier for the erosion of high-energy AO because of the stable cagelike Si-O frame in FP-POSS molecules. This should be chiefly responsible for the high stability of FP-POSS and the reinforcement mechanism of FP-POSS on PVDF against AO impacts. This work is helpful for people to understand the erosion details of PVDF and POSS and provides valuable information to design effective protective structure for PVDF against AO impacts in LEO environment.