The objective of this study was to evaluate the physicomechanical properties of a series of polyhedral silsesquioxane (SSQ) methacrylate monomers developed for dental applications. The effect of chain modifications on the properties of the SSQ-based monomers was also evaluated. Physicomechanical properties that are investigated include polymerization shrinkage, degree of conversion, hardness, and modulus. Results obtained were compared with unfilled 1:1 (control) bis-GMA/TEGDMA materials (typical monomers used in dental composites). All samples investigated were cured using 400-500 nm light at 500 mW/cm(2) for 40 s. Shrinkage associated with curing and post-gel reactions for all synthesized SSQ compounds were found to range from (0.04 +/- 0.01)% to (0.33 +/- 0.03)% with degree of conversion ranging from (56.68 +/- 2.81)% to (84.53 +/- 2.62)%. At all time intervals, post-gel shrinkage associated with control was found to be significantly greater than all SSQ compounds. No significant difference in degree of conversion was observed for control, and all SSQ compounds except for SSQ attached with eight equivalents of short-chain methacrylate. Mechanical properties associated with SSQ compounds were found to be significantly lower than control. However, through chain modifications, mechanical properties of SSQ compounds can be improved by approximately 50%.
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http://dx.doi.org/10.1002/jbm.b.30919 | DOI Listing |
Biomacromolecules
September 2024
Department of Biomedical Engineering, University of Delaware, Newark 19716, Delaware, United States.
Tissue hydration provides articular cartilage with dynamic viscoelastic properties. Early stage osteoarthritis (OA) is marked by loss of proteoglycans and glycosaminoglycans (GAG), lowering fixed charge density, and impairing tissue osmotic function. The most common GAG replacement, chondroitin sulfate (CS), has failed to show effectiveness.
View Article and Find Full Text PDFMaterials (Basel)
May 2024
Centre for Advanced Technologies, Adam Mickiewicz University Poznan, ul. Uniwersytetu Poznanskiego 10, 61-614 Poznan, Poland.
This study delineates a methodology for the preparation of new composites based on a photocurable urethane-acrylate resin, which has been modified with (3-thiopropyl)polysilsesquioxane (SSQ-SH). The organosilicon compound combines fully enclosed cage structures and incompletely condensed silanols (a mixture of random structures) obtained through the hydrolytic condensation of (3-mercaptopropyl)trimethoxysilane. This process involves a thiol-ene "click" reaction between SSQ-SH and a commercially available resin (Ebecryl 1271) in the presence of the photoinitiator DMPA, resulting in composites with significantly changed thermal properties.
View Article and Find Full Text PDFTalanta
July 2024
School of Pharmacy, Naval Medical University, Shanghai, 200433, China; Shanghai Key Laboratory for Pharmaceutical Metabolite Research, Shanghai, 200433, China. Electronic address:
J Neurol
May 2024
Department of Neurology and Center for Translational Neuro- and Behavioral Sciences (C-TNBS), University Hospital Essen, Hufelandstr. 55, 45147, Essen, Germany.
Background: 5q-associated spinal muscular atrophy (SMA) is characterized by the progressive loss of motor neurons with consecutive weakness and atrophy of the limb, respiratory, and bulbar muscles. While trunk and limb motor function improve or stabilize in adults with SMA under nusinersen and risdiplam treatment, the efficacy on bulbar function in this age group of patients remains uncertain. However, it is important to assess bulbar dysfunction, which frequently occurs in the disease course and is associated with increased morbidity and mortality.
View Article and Find Full Text PDFChempluschem
June 2022
Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, 61-614, Poznań, Poland.
This article presents the synthesis of new derivatives of octa(3-thiopropyl)silsesquioxane (SSQ-8SH) via thiol-ene reaction with simple olefins bearing alkyl groups as well as methoxysilyl, substituted aryl or fluoroalkyl groups. All products were characterized by H NMR, C NMR, Si NMR, FTIR, GPC, MALDI-TOF-MS, as well as thermal analysis (TGA) to confirm their structures, purity and thermal stability, and finally give some insight into their thermal degradation pathway. In some of the structures obtained, the T values take place at high temperatures and are close to 230 °C.
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