Enhancing the Thermal Resistance of UV-Curable Resin Using (3-Thiopropyl)polysilsesquioxane.

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. Various tests were conducted, including thermogravimetric analysis (TGA), Fourier transmittance infrared spectroscopy (FT-IR), differential scanning calorimetry (Photo-DSC), and photoreological measurement mechanical property, and water contact angle (WCA) tests. The modification of resin with SSQ-SH increased the temperature of 1% and 5% mass loss compared to the reference (for 50 wt% SSQ-SH, T5% was 310.8 °C, an increase of 20.4 °C). A composition containing 50 wt% of SSQ-SH crosslinked faster than the reference resin, a phenomenon confirmed by photorheological tests. This research highlights the potential of new composite materials in coating applications across diverse industries. The modification of resin with SSQ-SH not only enhances thermal properties but also introduces a host of functional improvements, thereby elevating the performance of the resulting coatings.

Preparation and Characterization of Composites Based on ABS Modified with Polysiloxane Derivatives.

In this study, organosilicon compounds were used as modifiers of filaments constituting building materials for 3D printing technology. Polymethylhydrosiloxane underwent a hydrosilylation reaction with styrene, octadecene, and vinyltrimethoxysilane to produce new di- or tri-functional derivatives with varying ratios of olefins. These compounds were then mixed with silica and incorporated into the ABS matrix using standard processing methods. The resulting systems exhibited changes in their physicochemical and mechanical characteristics. Several of the obtained composites (e.g., modified with VT:6STYR) had an increase in the contact angle of over 20° resulting in a hydrophobic surface. The addition of modifiers also prevented a decrease in rheological parameters regardless of the amount of filler added. In addition, comprehensive tests of the thermal decomposition of the obtained composites were performed and an attempt was made to precisely characterize the decomposition of ABS using FT-IR and optical microscopy, which allowed us to determine the impact of individual groups on the thermal stability of the system.

Trimming flow, plasticity, and mechanical properties by cubic silsesquioxane chemistry.

In this work, the possibility of managing the rheological and mechanical parameters of composites based on PLA with the use of cubic structures of organofunctional spherosilicates was verified. To accurately observe the effect of various organosilicon modifier substitutions on changes in composites' properties, we synthesized and used monofunctional octasubstituted derivatives as reference systems. The OSS/PLA systems were tested with concentrations of 0.1-2.5% (w/w) using extrusion to obtain a filament with a diameter of 1.75 mm. The printed samples underwent comprehensive tests including microscopic (SEM-EDS, optical microscope), rheological, thermal (TG, DSC, HDT), mechanical (impact and strength) as well as water contact angle tests. The work is interdisciplinary in nature and combines elements of organosilicon synthesis, materials engineering, and materials processing and characterization technology.

The 3D-Printed (FDM/FFF) Biocomposites Based on Polylactide and Carbonate Lake Sediments-Towards a Circular Economy.

In this study, composites containing polylactide and carbonate lake sediment in concentrations of 2.5, 5, 10, and 15% by weight were prepared by a 3D printing method. The material for 3D printing was obtained by directly diluting the masterbatch on an injection moulder to the desired concentrations, and after granulation, it was extruded into a filament. The material prepared thusly was used to print standardised samples for mechanical testing. To compare the mechanical properties of the composites obtained by 3D printing and injection moulding, two sets of tests were performed, i.e., mechanical tests (tensile strength, flexural strength, and impact strength) and hydrophobic-hydrophilic surface character testing. The degree of composite waste in the 3D printing was also calculated. Mechanical and surface tests were performed for both systems conditioned at room temperature and after accelerated ageing in a weathering chamber. The study showed differences in the properties of composites obtained by 3D printing. Sedimentary fillers improved the hydrophobicity of the systems compared with pure PLA, but it was not a linear relationship. The PLA/CLS sedB composite had higher strength parameters, especially after ageing in a weathering chamber. This is due to its composition, in which, in addition to calcite and silica, there are also aluminosilicates, causing a strengthening of the PLA matrix.

Feldspar-Modified Methacrylic Composite for Fabrication of Prosthetic Teeth.

This study was aimed at investigating poly(methyl methacrylate) (PMMA), modified with a silanized feldspar filler at 10 wt.% and 30 wt.%, as a dental material system for the production of prosthetic teeth. Samples of this composite were subjected to a compressive strength test, three-layer methacrylic teeth were fabricated with the said materials, and their connection to a denture plate was examined. The biocompatibility of the materials was assessed via cytotoxicity tests on human gingival fibroblasts (HGFs) and Chinese hamster ovarian cells (CHO-K1). The addition of feldspar significantly improved the material's compressive strength, with neat PMMA reaching 107 MPa, and the addition of 30% feldspar raising it up to 159 MPa. As observed, composite teeth (cervical part made of neat PMMA, dentin with 10 wt.%, and enamel with 30 wt.% of feldspar) had good adhesion to the denture plate. Neither of the tested materials revealed any cytotoxic effects. In the case of hamster fibroblasts, increased cell viability was observed, with only morphological changes being noticed. Samples containing 10% or 30% of inorganic filler were determined to be safe for treated cells. The use of silanized feldspar to fabricate composite teeth increased their hardness, which is of significant clinical importance for the duration of use of non-retained dentures.

Molybdenum Disulphide Modified Polylactide for 3D Printed (FDM/FFF) Filaments.

MoS2 is an additive used to improve the tribological properties of plastics. In this work, it was decided to verify the use of MoS2 as a modifier of the properties of PLA filaments used in the additive FDM/FFF technique. For this purpose, MoS2 was introduced into the PLA matrix at concentrations of 0.025-1.0% by weight. Through extrusion, a fibre with a diameter of 1.75 mm was obtained. 3D printed samples with three different filling patterns were subjected to comprehensive thermal (TG, DSC and HDT), mechanical (impact, bending and strength tests), tribological and physicochemical characteristics. The mechanical properties were determined for two different types of fillings, and samples with the third type of filling were used for tribological tests. Tensile strength has been significantly increased for all samples with longitudinal filling with improvement up to 49%. In terms of tribological properties, higher values of the addition (0.5%) caused a significant increase of up to 457% of the wear indicator. A significant improvement in processing properties in terms of rheology was obtained (416% compared to pure PLA with the addition of 1.0%), which translated into more efficient processing, increased interlayer adhesion and mechanical strength. As a result, the quality of printed objects has been improved. Microscopic analysis was also carried out, which confirmed the good dispersion of the modifier in the polymer matrix (SEM-EDS). Microscopic techniques (MO, SEM) allowed for the characterization of the effect of the additive on changes in the printing process (improvement of interlayer remelting) and to assess impact fractures. In the tribological area, the introduced modification did not bring spectacular effects.

Hydro- and Icephobic Properties and Durability of Epoxy Gelcoat Modified with Double-Functionalized Polysiloxanes.

Anti-icing coatings have provided a very good alternative to current, uneconomic, active deicing methods, and their use would bring a number of significant benefits to many industries, such as aviation and energy. Some of the most promising icephobic surfaces are those with hydrophobic properties. However, the relationship between hydrophobicity and low ice adhesion is not yet clearly defined. In this work, chemical modification of an epoxy gelcoat with chemical modifiers from the group of double organofunctionalized polysiloxanes (generally called multifunctionalized organosilicon compounds (MFSCs)) was applied. The anti-icing properties of manufactured coatings were determined by means of measurements of shear strength between the ice layer and the modified surface, conducted using a tensile machine. In the work, tests were also performed on the roughness, wettability, and durability of the properties in an aging chamber. It was found that the performed modifications of the coating's chemical composition by the addition of polysiloxanes enabled us to reduce ice adhesion by 51% and to increase the water contact angle by 14% in comparison to the neat gelcoat. A reduction in ice adhesion was also observed with the increasing water contact angle and with decreasing surface roughness. In addition, only one modification recorded an increase in ice adhesion after exposure in the aging chamber.

Silane-Bearing Borasilsesquioxanes: Synthetic Protocol and Unsuspected Redistribution Reactions.

The presented work is a continuation of research on the reactivity of unsaturated borasilsesquioxanes under the conditions of common organometallic transformations. The catalytic hydrosilylation reaction with silanes, siloxanes and silsesquioxanes in presence of platinum catalyst was explored. The majority of the products were obtained in high yields (>90 %) and their structures were confirmed and characterized by spectroscopy and spectrometry, i. e. NMR and MALDI-TOF-MS. The most significant segment of the work is research on the spontaneous redistribution reaction of the alkoxy group from silane to borane moiety occurring in the obtained products, not being limited to the heterosilsesquioxane chemistry, however. The products were confirmed using GC-MS, ESI-MS methods and B3LYP exchange-correlation, in order to ascertain formation of the silicon-boron hybrid molecule.

The Influence of Organofunctional Substituents of Spherosilicates on the Functional Properties of PLA/TiO2 Composites Used in 3D Printing (FDM/FFF).

In this study, the influence of TiO2 pigment filler modified with spherosilicate derivatives on the processes and thermomechanical properties of composites based on PLA was investigated. Rheological tests (MFR) were carried out, on the basis of which it was found that the addition of organosilicon compounds has a plasticizing effect on the polymer-filler systems. TGA and DSC analysis were performed. The analysis of the contact angle showed that 1.5% of the additives had an influence on the superhydrophobic properties of TiO2 (above 135°), and a slight improvement of this parameter was also observed for composites containing the modified pigment. Microscopic analysis and mechanical tests (tensile strength, impact strength and flexural strength tests) were carried out as well. It has been observed that the addition of certain derivatives adversely affects the dispersion of the filler, thus a slight improvement in mechanical properties is observed. For modifiers that do not affect filler agglomeration, a plasticizing effect on the composite is observed.

Carbonate Lake Sediments in the Plastics Processing-Preliminary Polylactide Composite Case Study: Mechanical and Structural Properties.

In this study, the influence of carbonate lake sediments (Polylactide/Carbonate Lake Sediments-PLA/CLS) on the mechanical and structural properties of polylactide matrix composites was investigated. Two fractions of sediments originating from 3-8 and 8-12 m were analysed for differences in particle size by distribution (Dynamic Light Scattering-DLS), phase composition (X-ray Diffraction-XRD), the presence of surface functional groups (Fourier Transform-Infrared-FT-IR), and thermal stability (Thermogravimetric Analysis-TGA). Microscopic observations of the composite fractures were also performed. The effect of the precipitate fraction on the mechanical properties of the composites before and after conditioning in the weathering chamber was verified through peel strength, flexural strength, and impact strength tests. A melt flow rate study was performed to evaluate the effect of sediment on the processing properties of the PLA/CLS composite. Hydrophobic-hydrophilic properties were also investigated, and fracture analysis was performed by optical and electron microscopy. The addition of carbon lake sediments to PLA allows for the obtention of composites resistant to environmental factors such as elevated temperature or humidity. Moreover, PLA/CLS composites show a higher flow rate and higher surface hydrophobicity in comparison with unmodified PLA.

Sulfur-Containing Silsesquioxane Derivatives Obtained by the Thiol-ene Reaction: Synthesis and Thermal Degradation.

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 1 H NMR, 13 C NMR, 29 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 T5% values take place at high temperatures and are close to 230 °C. The thiol-ene reaction allowed to obtain 7 new compounds with high yield (>92 %), no by-products and in a relatively short time (24 h). All products are characterized by high conversion >99 %. New derivatives can find potential use as modifiers of plastics to improve their certain properties for example hydrophobicity or thermo-oxidative stability.

Novel Multifunctional Spherosilicate-Based Coupling Agents for Improved Bond Strength and Quality in Restorative Dentistry.

The aim of this study was to investigate the restorative connections of composite materials after fracture, under controlled conditions of treating the materials with novel, spherosilicate-based (SS) primers bearing both methacryl (MA) and trimethoxysilyl (TMOS) groups. The chemistry of methacrylate group insertion and reactive groups hydrolysis has been studied with the aid of 1H NMR (Nuclear Magnetic Resonance) spectroscopy. The light-cured resin composites were repaired by activating the connection site with the obtained primers and, for comparison, a silane (methacryloxypropyltrimethoxysilane, MATMOS) as a conventional coupling agent bearing the same reactive groups. The resistance of such a joint was tested in a three-point bending test after 24 h and 28 days period of sample conditioning. The effect of bond application was also studied, showing that spherosilicate-based primers may be used more effectively than MATMOS for two-step (primer-composite) restorative process, while for silane, the three-step process with bond application is crucial for satisfactory joint quality. The joint failure mode was determined by microscopic analysis and it was found that SS-4MA-4TMOS and SS-2MA-6TMOS application resulted in mostly composite, and not joint, failure. After 28 days of conditioning, the flexural strength of the joint repaired with SS-4MA-4TMOS was at 94% of the neat, solid material under the same procedure. However, the strength of the neat composite was observed to decline during the conditioning process by ~30%. The joint behavior was explained on the basis of the gradual hydrolysis effect (the greatest decrease being observed for silane).

Where ppm Quantities of Silsesquioxanes Make a Difference-Silanes and Cage Siloxanes as TiO2 Dispersants and Stabilizers for Pigmented Epoxy Resins.

In this work, silsesquioxane and spherosilicate compounds were assessed as novel organosilicon coupling agents for surface modification of TiO2 in a green process, and compared with their conventional silane counterparts. The surface-treated TiO2 particles were then applied in preparation of epoxy (EP) composites and the aspects of pigment dispersion, suspension stability, hiding power, as well as the composite mechanical and thermal properties were discussed. The studied compounds loading was between 0.005-0.015% (50-150 ppm) in respect to the bulk composite mass and resulted in increase of suspension stability and hiding power by over an order of magnitude. It was found that these compounds may be an effective alternative for silane coupling agents, yet due to their low cost and simplicity of production and manipulation, silanes and siloxanes are still the most straight-forward options available. Nonetheless, the obtained findings might encourage tuning of silsesquioxane compounds structure and probably process itself if implementation of these novel organosilicon compounds as surface treatment agents is sought for special applications, e.g., high performance coating systems.

Novel Silsesquioxane-Derived Boronate Esters-Synthesis and Thermal Properties.

The functionalization of mono- and octahydrospherosilicate with vinylboranes and allylboranes via hydrosilylation reaction in the presence of a Karstedt's platinum (0) catalyst is presented. This is the catalytic route to obtain a new class of silsesquioxanes containing boron atoms in their structure in high yields (>90%) and with satisfactory selectivity. The obtained compounds were fully characterized by spectroscopic (1H, 13C, 29Si NMR) and spectrometric methods (MALDI-TOF-MS), as well as thermal analysis (TGA). The obtained compounds were subjected to thermal tests, characterizing the processes of melting, thermal evaporation, sublimation and thermal decomposition.

Why POSS-Type Compounds Should Be Considered Nanomodifiers, Not Nanofillers-A Polypropylene Blends Case Study.

In this work, a series of silsesquioxanes (SSQ) and spherosilicates (SS), comprising a group of cage siloxane (CS) compounds, was tested as functional additives for preparation of isotactic polypropylene (iPP)-based nanocomposites and discussed in the aspect of their rationale of applicability as such additives. For this purpose, the compounds were prepared by condensation and olefin hydrosilylation reactions. The effect of these cage siloxane products on properties of obtained CS/iPP nanocomposites was analyzed by means of mechanical, microscopic (scanning electron microscopy-energy dispersive spectroscopy), thermal (differential scanning calorimetry, thermogravimetry), thermomechanical (Vicat softening point) analyses. The results were compared with the previous findings on CS/polyolefin composites. The role of CS compounds was discussed in terms of plastic processing additives.

Limonene Derivative of Spherosilicate as a Polylactide Modifier for Applications in 3D Printing Technology.

The first report of using limonene derivative of a spherosilicate as a modifier of polylactide used for 3D printing and injection moulding is presented. The paper presents the use of limonene-functionalized spherosilicate derivative as a functional additive. The study compared the material characteristics of polylactide modified with SS-Limonene (0.25-5.0% w/w) processed with traditional injection moulding and 3D printing (FFF, FDM). A significant improvement in the processing properties concerning rheology, inter-layer adhesion, and mechanical properties was achieved, which translated into the quality of the print and reduction of waste production. Moreover, the paper describes the elementary stages of thermal transformations of the obtained hybrid systems.