Search Results (68)

Cotton fabrics are widely used due to their comfort and biodegradability; however, their intrinsic hydrophilicity limits their performance in advanced applications. In this work, a fluorine-free approach for imparting durable hydrophobicity to cotton was developed based on thiol-ene crosslinking of polysiloxane networks formed on the fiber surface. Two thiol-functional polysiloxanes differing in –SH group content were combined with four vinyl-functional organosilicon crosslinkers under UV (2,2-dimethoxy-2-phenylacetophenone (DMPA)) and thermal (2,2′-azobis(2-methylpropionitrile) (AIBN)) initiation. FT-IR analysis confirmed the presence of siloxane structures, while SEM-EDS revealed stable silicon- and sulfur-containing layers. SEM observations showed continuous coatings without blocking the textile structure. Water contact angle (WCA) measurements demonstrated that hydrophobic performance strongly depends on thiol content and crosslinker structure, with the highest values obtained for the thiol-rich polysiloxane and tetrafunctional vinyl crosslinker. All modified fabrics exhibited high durability, with minimal changes in WCA and complete droplet stability (1800 s) after washing. In the case of the lower-functionality polysiloxane, an increase in hydrophobicity after washing was observed, attributed to the reorganization of siloxane chains. These results demonstrate that thiol-ene crosslinking provides an effective strategy for designing durable, fluorine-free hydrophobic coatings on cotton. Full article

Biofouling is an issue of global significance that impairs marine infrastructure, causes increased fuel consumption and greenhouse gas emissions, and threatens biodiversity. Since the year 2000, self-polishing copolymer (SPC) coatings and fouling release coatings (FRCs) dominate the fouling protection coatings market. SPC technology is based on the controlled release of biocides using a mixture of acrylic and natural binders as a delivery system. FRC technology is based on PDMS providing surface properties that resist attachment of fouling organisms. FRCs often contain surface modifying agents, such as free silicone oils, to tune the physicochemical properties of the surface. However, the long-term efficacy of these agents and their migration and distribution in PDMS-based coatings have not been well studied. In this study, we employed time-of-flight secondary ion mass spectrometry (ToF-SIMS) combined with multivariate analysis to examine the distribution of silicone oils as a function of exposure to artificial seawater (ASW). The results show that pure PDMS-based coatings allow uniform distribution of silicone oils with robust behavior upon ASW exposure. In contrast, epoxy–PDMS-based coatings displayed phase separation of the oils, which strongly altered their surface chemistry. Our findings suggest that the modification of mobile oils is critical to the performance of marine antifouling coatings. Furthermore, the presence of other ingredients of commercial coating formulations strongly affected the distribution of mobile oils. This study lays the foundation for future systematic research aimed at developing predictive models to optimize fouling protection coatings for the marine industry. Full article

In the oral environment, silicone (polysiloxane) supports healing by creating low-permeability interfaces that limit microleakage, whereas silicon/silica systems support healing via hydroxyapatite nucleation. We synthesized human evidence on intraoral healing associated with silicone and silicon/silica-based materials and assessed translational differences between preclinical models and clinical settings. A systematic review (1990-September 2025) identified 14 clinical studies of bioactive glass (BAG) that met the inclusion criteria. Periodontal outcomes included probing depth (PD), clinical attachment level (CAL), and radiographic fill; endodontic outcomes included the periapical index (PAI). Human BAG studies showed periodontal benefits versus controls in intrabony defects, with reduced PD, improved CAL, and greater radiographic fill. For endodontic healing, a multicenter randomized clinical trial reported improved PAI at 12 months in both the zinc-oxide-eugenol and silicone-sealer groups without a significant between-group difference. The literature supports a functional split: silicone primarily provides sealing and permissive healing, whereas silicon/silica-based materials support signaling, interfacial bonding, and regenerative healing. Clinically, BAG appears most relevant for contained periodontal intrabony defects, whereas silicone sealers should be viewed primarily as stable sealing adjuncts to well-executed root canal therapy. Full article

Introduction of ferrocenyl-containing polysiloxanes onto the carbon nanotubes has paved the way to prospective electrochemical (bio)sensors, energy storage devices, optoelectronic devices, ion-separation systems, etc. In the study we compare covalent and non-covalent approaches of multi-walled carbon nanotubes functionalization by ferrocenyl-containing polysiloxanes, which were investigated by Raman and X-Ray photoelectron spectroscopy (XPS). The soft silicone composites based on the multi-walled carbon nanotubes (MWCNTs) modified via the two approaches were obtained and analyzed. Full article

The smoke toxicity of epoxy resin limits the application of its carbon fiber composites in marine interior structures. To address this issue, a novel epoxy resin (EZ) was synthesized by grafting phenyl propyl polysiloxane (PPPS) onto ortho-cresol novolac epoxy resin (EOCN), building upon the group’s earlier work on polysiloxane-modified epoxy resin (EB). The results confirmed successful grafting of PPPS onto EOCN, which significantly enhanced the thermal stability and char residue of EZ. Specifically, the peak heat release rate (PHRR), total heat release (THR), peak smoke production rate (PSPR), and total smoke production (TSP) of EZ were reduced by 68.5%, 35%, 73.1%, and 48.3%, respectively, attributable to the formation of a stable and compact char layer that suppressed smoke generation. By blending EZ with EB resin, a low-smoke epoxy system (LJF-2) was developed for prepreg applications. Carbon fiber composites (LJF-CF) prepared from LJF-2 exhibited minimal smoke emission and a unique bilayer char structure: a dense inner layer that hindered smoke transport and a thick outer layer that provided thermal insulation, delaying further resin decomposition. Silicon was uniformly distributed in the char residue as silicon oxides, improving its stability and compactness. Without adding any flame retardants or smoke suppressants, LJF-CF achieved a maximum smoke density (Ds,max) of 276.9, meeting the requirements of the FTP Code for ship deck materials (Ds,max < 400). These findings indicate that LJF-CF holds great promise for use in marine interior components where low smoke toxicity is critical. Full article

To enhance the high-temperature resistance of silicone rubber and meet the application requirements of flexible conductive silicone rubber under elevated temperature conditions, this study adopts a chemical modification strategy by introducing phenyl groups into the molecular chains of silicone rubber to improve its thermal resistance. High-phenyl-content hydroxyl-terminated silicone oil (MPPS) was used as the polymer backbone, and vinylmethyldimethoxysilane (VDMS) served as the chain extender. Through a silanol condensation reaction, vinylmethylphenyl polysiloxane (VMPPS) with a crosslinkable structure was synthesized, providing reactive sites for subsequent vulcanization and molding. Subsequently, needle-like silver-coated glass fiber (AGF) conductive fillers were prepared via a green and environmentally friendly electroless silver plating method. These fillers were incorporated into the phenyl polysiloxane matrix to impart electrical conductivity to the phenyl silicone rubber while synergistically enhancing its thermal resistance. Finally, thermally resistant conductive silicone rubber was fabricated through high-temperature vulcanization, and the key properties of the material were systematically characterized. The synthesized phenyl polysiloxane exhibited a number-averaged molecular weight of up to 181,136, with a PDI of 2.43. When the loading of AGF reached 25 phr, the phenyl silicone rubber composite achieved the electrical percolation threshold, exhibiting a conductivity of 7.12 S/cm. With a further increase in AGF content to 35 phr, the composite demonstrated excellent thermal stability, with a 5% weight loss temperature of 478 °C and a residual mass of 37.36% at 800 °C. Moreover, after thermal aging at 100 °C for 72 h, the conductivity degradation of the phenyl silicone rubber was significantly lower than that of commercial silicone rubber, indicating outstanding electrical stability. This study provides an effective approach for the application of flexible electronic materials under extreme thermal environments. Full article

A significant challenge during the polymer-to-ceramic pyrolysis conversion is to understand the polymer-to-ceramic atomic evolution and correlate the composition changes with the precursor molecular structures, pyrolysis conditions, and resulting ceramic characteristics. In this study, a Reactive Force Field (ReaxFF) simulation approach has been used to simulate silicon oxycarbide (SiOC) ceramic formation from four different polysiloxane precursors. For the first time, we show atomically that pyrolysis time and temperature proportionally impact the new Si-O rich and C rich cluster sizes as well as the composition separation of Si-O from C. Polymer side groups have a more complex effect on the Si-O and C cluster separation and growth, with ethyl group leading to the most Si-O cluster separation and phenyl group leading to the most C cluster separation. We also demonstrate never-before correlations of gas release with polymer molecular structures and functional groups. CH₄, C₂H₆, C₂H₄, and H₂ are preferentially released from the pyrolyzing systems. The sequence is determined by the polymer molecular structures. This work is the first to atomically illustrate the innate correlations between the polymer precursors and pyrolyzed ceramics. Full article

Condensation-type polysiloxane composites with montmorillonite (MMT) of different organic modifications were prepared in this study. X-ray diffraction (XRD) characterization revealed that the higher degree of organic modification in Cloisite 20A, compared to that in Cloisite 30B, resulted in a larger interlayer spacing between the clay platelets. This facilitates the insertion of elastomer chains between the layers, enabling easier exfoliation and dispersion in the elastomeric matrix. Differential scanning calorimetry (DSC) showed that the reinforcing agents used reduced the cold crystallization temperature of the condensation-type polysiloxane while leaving the glass transition and melting temperatures nearly unaffected. Additionally, the nanocomposites exhibited slightly lower crystallization and melting enthalpies compared to pure silicone. Thermogravimetric analysis (TGA) showed that incorporating the two organically modified clays (Cloisite 20A and Cloisite 30B) into the condensation-type polysiloxane significantly improved the thermal stability of the resulting nanocomposites. This improvement was reflected in the significant increase in the onset and maximum degradation rate temperatures across all examined reinforcement ratios. It was observed that a higher degree of organic modification in MMT (Cloisite 20A) resulted in a more efficient dispersion in the PDMS matrix and enhanced the thermal stability of the composites. These PDMS nanocomposites could be suitable as protective coatings for devices exposed to elevated temperatures. Full article

The effectiveness of ultraviolet-C light-emitting diodes (UVC LEDs) is currently limited by the lack of suitable encapsulation materials, restricting their use in sterilization, communication, and in vivo cancer tumor inhibition. This study evaluates various silicone oils for UVC LED encapsulation. A material aging experiment was conducted on CF1040 (octamethylcyclotetrasiloxane), HF2020 (methyl hydro polysiloxanes), and MF2020-1000 (polydimethylsiloxane) under UVC radiation for 1000 h. The analysis assessed transmittance changes and chemical composition alterations throughout the aging process. Notably, HF2020 showed an increase in transmittance before 500 h, indicating a curing process attributed to the photolysis of Si-H, leading to the formation of Si-O-Si. Further testing on 265 nm UVC LEDs, both with and without HF2020 encapsulation, showed that the encapsulated LEDs exhibited a remarkable maximum increase of 27% in radiant power compared to their unencapsulated counterparts. Additionally, these encapsulated LEDs sustained higher radiant power levels during the first 200 h of operation. Notably, its potential application in photodynamic therapy is significant; by activating photosensitizers with higher UVC exposure, it facilitates the rapid production of reactive oxygen species, leading to effective cancer cell destruction within a short timeframe. Full article

A series of Si-H- or Si-Vi-terminated, branched and linear oligomers containing Me₂SiO segments were prepared by equilibrium polymerization or non-equilibrium polymerization initiated by living anions, respectively. These oligomers were used to improve the defects of concentrated crosslinking points and the high hardness of crosslinked products when using phenyltris(dimethylsiloxy)silane or 1,1,5,5-tetramethyl-3,3-diphenyl trisiloxane as crosslinking agents in the preparation of silicone gel. NMR, FT-IR, and GPC characterized the structure and molecular weight information of the prepared oligomers. The effects of equilibrium polymerization and the anionic non-equilibrium ring-opening polymerization methods on the structure of oligomers were investigated in detail, together with the structure, the molar ratio of SiH to SiVi, and the phenyl content on the thermal properties and the transmittance retention yield of the silicone gel. The introduction of phenyl groups increases the glass transition temperature of silicone gel from −121.29 °C to −117.71 °C when the phenyl content increased from 0.88 wt% to 3.17 wt%. Meanwhile, the thermal decomposition temperature of silicone gel at 10% weight loss in the N₂ atmosphere increased from 440.5 °C to 480.0 °C. When the SiH/SiVi molar ratio is close to 1.0, the transmittance retention yield of the prepared silicone gel using Si-Vi-terminated phenyl T-shaped polysiloxane as the matrix and α, ω-dimethylsiloxyl-terminated PDMS as the crosslinking agent could reach 88.9% after 25 min of UV irradiation. Full article

Objective: This study aimed to assess and compare the internal fit of custom-made posts and cores fabricated using digital impressions (DI) and conventional vinyl polysiloxane (VPS) impressions in restorative dentistry. Materials and Methods: A typodont tooth model, simulating the anatomy of the root canal of a central incisor, was utilized for the study. Two groups were formed, Group A and Group B, and each group provided a total of 18 impressions of two types: DIs and VPS impressions. In Group A, posts and cores (PCs) were fabricated using Selective Laser Melting (SLM) from the DIs. Meanwhile, in Group B, conventionally cast (CC) PCs were created from the VPS impressions. Silicone replicas of the internal surfaces were produced, and measurements were made at seven different points for each group. A statistical analysis was performed to assess the differences in internal fit between the two impression techniques. Results: The results revealed a statistically significant difference in mean internal fit between Group A (DI and SLM) and Group B (VPS and CC), with Group A exhibiting a mean internal fit of 182.6 µm and Group B showing a mean of 205.9 µm. While both groups demonstrated considerable variability in internal fit measurements, the digital impression technique showed promise for achieving superior internal fit, with a significantly greater fit for measuring points on sides and the most apical part of the post for Group A. Variations were observed across different measuring points, emphasizing the impact of impression technique on specific regions within the tooth. Conclusion: This study contributes to the growing body of knowledge in digital dentistry by highlighting the potential benefits of DIs in achieving a superior internal fit for custom-made PCs. Clinicians may consider the advantages of digital techniques to enhance the precision of their restorative procedures, although further research is warranted to evaluate the clinical impact of these findings. Full article

Film-forming agents are key ingredients in achieving long-lasting and effective sun protection by sunscreens. However, studies on the synergistic effects of film-forming agents with different properties as well as the interaction between film-forming agents and powders are scarce, restricting the development of sunscreens with strong ultraviolet (UV)-shielding effects. Herein, we innovatively adopt polysiloxane-15 as the soft film, trimethylsiloxysilicate as the hard film, and vinyl dimethicone/methicone silsesquioxane crosspolymer as the functional powder to construct a co-assembled sunscreen film, and we investigate the property-enhancing effects of the sunscreen film as well as the interaction between the silicone polymer-based film-forming agents and functional powder therein. The results show that structural similarity is essential to generating film-forming agent–powder interactions, which primarily enhance the Si−O bond binding energy, thereby enhancing the lasting protection effect of sunscreens. In addition, the inter-component interaction of the co-assembled sunscreen film inhibits the agglomeration of sunscreen paste to facilitate the formation of a homogeneous film, endowing the sunscreen with excellent UV protection abilities, with the sun protection factor (SPF) and protection factor of UVA (PFA) values increased by 61.58 and 43.84%, respectively. This work offers novel insights into the optimization of film-forming agent properties and the development of durable and efficient sunscreens. Full article

Polysiloxanes with silver nanoparticles (Ag NPs) have garnered attention for their distinctive physicochemical properties, which make them promising candidates for advanced material applications. This study presents a systematic investigation into the thermal properties and degradation mechanisms of polysiloxane/Ag nanocomposites, emphasising the innovative incorporation of Ag NPs directly into polysiloxane networks via in situ reduction of Ag⁺ ions by Si-H groups. Six polysiloxane matrices were synthesised by hydrosilylation of poly(methylhydrosiloxane) (PMHS) or poly(vinylsiloxane) (polymer V₃) with three cross-linking agents of varying molecular structures and functionality. Thermogravimetric analysis combined with mass spectrometry revealed that the introduction of Ag NPs alters the thermal properties of polysiloxane networks, primarily affecting the redistribution of Si bonds that occurs during the pyrolysis of these systems. Monitoring the pyrolysis process using FTIR spectroscopy allowed us to investigate the effect of the presence of Ag NPs on the degradation mechanism of the studied nanocomposites. The presence of the free-carbon phase and metallic silver phase in the Ag-containing silicon oxycarbide materials obtained was confirmed by Raman spectroscopy and XRD analyses, respectively. These findings demonstrate the possibility of fabricating Ag/SiOC materials with ceramic residues in the range of 43 to 84%. This work provides new insights into the thermal behaviour of polysiloxane/Ag nanocomposites and underscores their potential for high-performance applications in thermally demanding environments. Full article

Three-dimensional printing is ideally suited to produce unique and complex shapes. In this study, the material properties of polysiloxanes, commonly named silicones, produced additively by two different methods, namely, multi-jet fusion (MJF) and material extrusion (ME) with liquid printing heads, are investigated. The chemical composition was compared via Fourier-transform infrared spectroscopy, evolved gas analysis mass spectrometry, pyrolysis gas chromatography coupled to mass spectrometry, and thermogravimetry (TGA). Density and low-temperature flexibility, mechanical properties and crosslink distance via freezing point depression were measured before and after post-treatment at elevated temperatures. The results show significant differences in the chemical composition, material properties, as well as surface quality of the tested products produced by the two manufacturing routes. Chemical analysis indicates that the investigated MJF materials contain acrylate moieties, possibly isobornyl acrylate linking branches. The hardness of the MJF samples is associated with crosslinking density. In the ashes after TGA, traces of phosphorus were found, which could originate from initiators or catalysts of the curing process. The ME materials contain fillers, most probably silica, that differ in their amount. It is possible that silica also plays a role in the processing to stabilize the extrusion strand. For the harder material, a higher crosslink density was found, which was supported also by the other tested properties. The MJF samples have smooth surfaces, while the ME samples show grooved surface structures typical for the material extrusion process. Post-treatment did not improve the material properties. In the MJF samples, significant color changes were observed. Full article

The evolution of 3D printing has ushered in accessibility and cost-effectiveness, spanning various industries including biomedical engineering, education, and microfluidics. In biomedical engineering, it encompasses bioprinting tissues, producing prosthetics, porous metal orthopedic implants, and facilitating educational models. Hybrid Additive Manufacturing approaches and, more specifically, the integration of Fused Deposition Modeling (FDM) with bio-inkjet printing offers the advantages of improved accuracy, structural support, and controlled geometry, yet challenges persist in cell survival, interaction, and nutrient delivery within printed structures. The goal of this study was to develop and present a low-cost way to produce physical phantoms of human organs that could be used for research and training, bridging the gap between the use of highly detailed computational phantoms and real-life clinical applications. To this purpose, this study utilized anonymized clinical Computed Tomography (CT) data to create a liver physical model using the Creality Ender-3 printer. Polylactic Acid (PLA), Polyvinyl Alcohol (PVA), and light-bodied silicone (Polysiloxane) materials were employed for printing the liver including its veins and arteries. In brief, PLA was used to create a mold of a liver to be filled with biocompatible light-bodied silicone. Molds of the veins and arteries were printed using PVA and then inserted in the liver model to create empty channel. In addition, the PVA was then washed out by the final product using warm water. Despite minor imperfections due to the printer’s limitations, the final product imitates the computational model accurately enough. Precision adjustments in the design phase compensated for this variation. The proposed novel low-cost 3D printing methodology successfully produced an anatomically accurate liver physical model, presenting promising applications in medical education, research, and surgical planning. Notably, its implications extend to medical training, personalized medicine, and organ transplantation. The technology’s potential includes injection training for medical professionals, personalized anthropomorphic phantoms for radiation therapy, and the future prospect of creating functional living organs for organ transplantation, albeit requiring significant interdisciplinary collaboration and financial investment. This technique, while showcasing immense potential in biomedical applications, requires further advancements and interdisciplinary cooperation for its optimal utilization in revolutionizing medical science and benefiting patient healthcare. Full article