Thioether-Containing Zirconium(Alkoxy)Siloxanes: Synthesis and Study of Dielectric and Mechanical Properties of Silica-Filled Polydimethylsiloxane Compositions Cured by Them

Tarasenkov, А. N.; Parshina, Maria S.; Goncharuk, G. P.; Borisov, Kirill M.; Golubev, Evgenii K.; Meshkov, I. B.; Cherkaev, G. V.; Шевченко, В. Г.; Ponomarenko, Sergei A.; Muzafarov, А. М.

doi:10.3390/polym15163361

Cited by 2 publications

(1 citation statement)

References 44 publications

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“…The curing reaction of RTV silicone in this work is shown in Scheme b. , The moisture from the ambient environment hydrolyzed trimethoxy end groups of the PDMS polymer and formed the silanol-terminated PDMS polymer. The produced silanol PDMS reacted with trimethoxy-terminated PDMS for curing.…”

Section: Experiments and Materialsmentioning

confidence: 99%

Elucidating the Changes in Molecular Structure at the Buried Interface of RTV Silicone Elastomers during Curing

Lin,

Wu,

Santos

et al. 2024

Langmuir

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Silicone elastomers are widely used in many industrial applications, including coatings, adhesives, and sealants. Roomtemperature vulcanized (RTV) silicone, a major subcategory of silicone elastomers, undergoes molecular structural transformations during condensation curing, which affect their mechanical, thermal, and chemical properties. The role of reactive hydroxyl (−OH) groups in the curing reaction of RTV silicone is crucial but not well understood, particularly when multiple sources of hydroxyl groups are present in a formulated product. This work aims to elucidate the interfacial molecular structural changes and origins of interfacial reactive hydroxyl groups in RTV silicone during curing, focusing on the methoxy groups at interfaces and their relationship to adhesion. Sum frequency generation (SFG) vibrational spectroscopy is an in situ nondestructive technique used in this study to investigate the interfacial molecular structure of select RTV formulations at the buried interface at different levels of cure. The primary sources of hydroxyl groups required for interfacial reactions in the initial curing stage are found to be those on the substrate surface rather than those from the ingress of ambient moisture. The silylation treatment of silica substrates eliminates interfacial hydroxyl groups, which greatly impact the silicone interfacial behavior and properties (e.g., adhesion). This study establishes the correlation between interfacial molecular structural changes in RTV silicones and their effect on adhesion strength. It also highlights the power of SFG spectroscopy as a unique tool for studying chemical and structural changes at RTV silicone/ substrate interface in situ and in real time during curing. This work provides valuable insights into the interfacial chemistry of RTV silicone and its implications for material performance and application development, aiding in the development of improved silicone adhesives.

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Section: Experiments and Materialsmentioning

confidence: 99%

Elucidating the Changes in Molecular Structure at the Buried Interface of RTV Silicone Elastomers during Curing

Lin,

Wu,

Santos

et al. 2024

Langmuir

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Compressive modulus, translucency, and irradiance transmittance of clear PVS materials used for resin injection molding technique

Machado,

Rocha,

Oliveira

et al. 2024

J Esthet Restor Dent

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ObjectivesTo evaluate the compressive modulus, translucency, and light curing irradiance transmittance of four clear polyvinyl siloxane (PVS) materials used for the injection molding technique at varying thicknesses, and to assess the correlation between color parameters and irradiance transmittance.Materials and MethodsFour clear PVS materials (Exaclear, Clear Bite Matrix, Affinity Crystal, and Memosil 2) were used in this study. Compressive modulus was measured by compressing cylindrical PVS specimens (n = 9; d = 10 mm; t = 6 mm) up to 30% strain using a universal testing machine. For the translucency analysis and irradiance transmittance, specimens (n = 5) were fabricated with five different thicknesses (d = 12 mm and t = 2, 4, 6, 8 and 10 mm). The L*, a, *b* values of specimens were obtained using a CIELab spectrophotometer (CMD‐700, Konica Minolta) with calibrated white and black tiles; the translucency parameter was calculated. The same specimens were placed onto a spectrophotometer (MARC Light Collector) to measure irradiance transmitted through the specimens from a light curing unit (Valo Corded, Ultradent). Data were analyzed using analysis of variance (ANOVA) with Tukey post hoc test and the correlation between translucency and irradiance transmittance of materials for each thickness was evaluated using Pearson's correlation.ResultsCompressive modulus differences in PVS materials were significant (one‐way ANOVA: df = 3, F = 76.27, p < 0.001); Affinity and Memosil 2 were highest with no significant difference between them (Tukey: t = −1.62; p = 0.382). Clear Bite was higher than Exaclear (Tukey: t = −3.70; p = 0.004). Exaclear was lowest. Translucency decreased with thickness (Two‐way ANOVA: df = 3, F = 586.53, p < 0.001; thickness: df = 4, F = 1389.34, p < 0.001). Exaclear was most translucent at all thicknesses. L*, a*, b* values varied by material and thickness (L*: df = 3, F = 1213.32, p < 0.001; a*: df = 3, F = 10766.8, p < 0.001; b*: df = 3, F = 3260.42, p < 0.001). Memosil 2 had lowest b* values. Irradiance transmittance was affected by material and thickness (Two‐way ANOVA: df = 4, F = 2388.86, p < 0.001). Exaclear had highest irradiance transmission, surpassing control at >6 mm. Violet/blue irradiance ratio decreased with thickness; Exaclear maintained a constant ratio, indicating preserved violet irradiance. There was a strong positive correlation between translucency and light irradiance (Pearson's r = 0.97, R2 = 0.86–0.96). Radiant exposure analysis suggests adjusting the curing time based on PVS thickness for optimal exposure (10 J/cm2) is achievable within 13–14 s for <2 mm and 21–30 s for 8–10 mm with Clear Bite, Affinity, and Memosil 2; whereas Exaclear requires less time.ConclusionsCompressive modulus in clear PVS materials varied by type; Affinity and Memosil 2 demonstrate higher modulus, offering more stability of the clear mold. Translucency and irradiance transmission through clear PVS materials decreased as their thickness increased, yet Exaclear exceled in maintaining high translucency and superior light transmission capabilities. Additionally, there is a strong positive linear correlation between translucency and light irradiance transmittance, offering a method to adjust curing times effectively based on material translucency.Clinical SignificanceThe light curing time to adequately polymerize composite through clear impression material may need to be increased, particularly with thicker matrices or less translucent materials.

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Thioether-Containing Zirconium(Alkoxy)Siloxanes: Synthesis and Study of Dielectric and Mechanical Properties of Silica-Filled Polydimethylsiloxane Compositions Cured by Them

Cited by 2 publications

References 44 publications

Elucidating the Changes in Molecular Structure at the Buried Interface of RTV Silicone Elastomers during Curing

Elucidating the Changes in Molecular Structure at the Buried Interface of RTV Silicone Elastomers during Curing

Compressive modulus, translucency, and irradiance transmittance of clear PVS materials used for resin injection molding technique

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