Photocrosslinking of Silicones. Part 13. Photoinduced Thiol-Ene Crosslinking of Modified Silicones

Müller, Uwe; Kunze, Annett; Herzig, Christian; Weis, Johann

doi:10.1080/10601329608010869

Cited by 32 publications

(37 citation statements)

References 20 publications

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“…The system did not undergo ene homopolymerization, as indicated with copolymerization parameter products ( r 1 ∙ r 2 ) that were lower than 10 −3 , which is a value typical for copolymerizations yielding alternating copolymer products . The enthalpy of thiol addition across the olefin used was calculated from Hess's law and measured using DSC, providing values of 121 and 93 kJ mol −1 , respectively . Experimentally determined reaction enthalpy values were consistently lower than calculated ones, likely due to incomplete conversion of ene groups.…”

Section: Resultsmentioning

confidence: 88%

“…Müller et al. described the photo‐induced radical crosslinking of an α,ω‐ene‐terminated polysiloxane with vinylsilyl endgroups and a thiol‐containing polysiloxane, which showed nearly 100% thiol and 98% ene functional group consumption and a first‐order, linear relationship between the reaction rate ( R p ) and the incident light intensity when stoichiometric mixtures were reacted in air . The system did not undergo ene homopolymerization, as indicated with copolymerization parameter products ( r 1 ∙ r 2 ) that were lower than 10 −3 , which is a value typical for copolymerizations yielding alternating copolymer products .…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, the step‐growth polymerization kinetics of thiol–ene reactions allows for higher overall conversions prior to vitrification as compared to typical addition polymerization (e.g., acrylates), which results in reduced polymerization shrinkage and improved network homogeneity . Consequently, the thiol–ene reaction offers attractive advantages for covalently crosslinked polysiloxane elastomers …”

Section: Introductionmentioning

confidence: 99%

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3D Printing Amorphous Polysiloxane Terpolymers via Vat Photopolymerization

Sirrine

Zlatanić

Meenakshisundaram

et al. 2019

Macro Chemistry & Physics

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Photocuring and vat photopolymerization (VP) additive manufacturing (AM) is reported for two families of fully amorphous poly(dimethyl siloxane) (PDMS) terpolymers containing either diphenylsiloxy (DiPhS) or diethylsiloxy (DiEtS) repeating units. A thiol‐functionalized PDMS crosslinker enables rapid crosslinking in air using efficient thiol–ene addition. Differential scanning calorimetry and dynamic mechanical analysis (DMA) confirm the absence of crystallinity for the DiPhS‐containing systems, while DMA shows a rubbery plateau extending to greater than 200 °C for the DiEtS‐containing system. VP‐AM of both photopolymer systems afford well‐defined 3D geometries, including high aspect ratio structures, which demonstrate feasibility of these photopolymers for the 3D printing of unique geometric objects that require elastomeric performance to temperatures as low as −120 °C.

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

3D Printing Amorphous Polysiloxane Terpolymers via Vat Photopolymerization

Sirrine

Zlatanić

Meenakshisundaram

et al. 2019

Macro Chemistry & Physics

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“…Limonene represents an exceptionally versatile monomer for the introduction of new chemical functional groups that can be directed toward specific polymerization techniques . Characterization of cross‐linked PMMS in the molecular level is relatively difficult because of the insolubility of the network . To obtain a deeper understanding of the reaction sites and to further the cross‐linking, a small experiment using model compounds was designed.…”

Section: Resultsmentioning

confidence: 99%

Sunlight‐Induced Cross‐Linked Luminescent Films Based on Polysiloxanes and d‐Limonene via Thiol–ene “Click” Chemistry

Zuo

Cao

Feng

2015

Adv Funct Materials

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2754 wileyonlinelibrary.com radical polymerization. [ 5,9 ] Usually, fi lms or elastomers based on polysiloxanes are cross-linked by the following three main methods: 1) platinum-catalyzed hydrosilylation between vinyl groups and Si-H bond, 2) titanium-catalyzed condensation reaction of alkoxysilane with -OH-ended polysiloxanes, and 3) thermal-initiated free radical cross-linking reaction. However, most of these processes are catalyzed by heavy metals, [ 10,11 ] and metallic catalysts should be avoided from the standpoint of "green" chemistry. [ 12,13 ] Therefore, the establishment of a new general strategy to prepare a cross-linked polysiloxane network is imperative. The addition reaction between thiol and olefi ns to produce thioethers has been known for some time, and both Michael addition and free-radical addition mechanisms are depicted. [ 14,15 ] Thiol-ene "click" chemistry, a robust and environment-friendly radical-based, versatile, and rapid process in the presence of oxygen, could fulfi ll our anticipations. [16][17][18][19] However, most of the thiol-ene crosslink reactions are induced by UV light and can proceed at wavelengths of approximately 365 nm. [ 20,21 ] Even though thiol-ene reactions have been studied for a long time, covering different scientifi c fi elds from polymer science to biochemistry, only very few examples have been reported on thiol-ene additions irradiated by natural sunlight. [ 21,22 ] The generation of thiyl radicals using solar radiation should be possible. To the best of our knowledge, literature on cross-linking networks realized by sunlight induced thiol-ene reaction is not present to date. Thus, we focused on a novel cross-linking system synthesized under sunlight. Compared with the conventional thiol-ene reactions triggered by UV light, a sunlight-induced reaction indicates a "greener" method that does not need excessive power.However, the typically unpleasant odors of low-molecular-weight thiols also have limited their commercial utilization. [ 23,24 ] To overcome these disadvantages and to obtain photo curing materials based on poly[(mercaptopropyl)methylsiloxane] (PMMS) with enhanced performance, we introduced D -limonene containing two different vinyl groups into PMMS to develop a novel sunlight-cured hybrid material. To take advantage of the physical and mechanical properties of polysiloxanebased materials and to allow connection with other functional molecules, PMMS was chosen as the base component for the siloxane-based systems.The increasing pursuit of biocontained elastic materials led the investigation of the potential use of the monoterpene limonene in fi lm synthesis via thiol-ene reaction. Poly[(mercaptopropyl)methylsiloxane] (PMMS) is fi rst synthesized. By controlling the molar ratio of PMMS and functional monomers, such as polyethylene glycol allyl methyl ether or rhodamine-B, PMMS is partially functionalized while leaving spare mercapto groups that could be further used as cross-linking sites. On the basis of the functionalized PMMS, novel transparent silic...

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“…Studies have been done extensively on UV curing of acrylic silicones7 or classical condensation curing by UV light,8 but very few examples on vinyl‐terminated silicones are available in the literature 9. Previously prepared UV‐curable PDMS systems rely on low‐molecular‐weight linear PDMS, which results in heavily cross‐linked hard networks 9b,c. To overcome the drawbacks exhibited by platinum‐catalyzed curing of silicones, photoinitiated thiol–ene cross‐linking of high‐molecular‐weight PDMS prepolymers have been investigated as a pathway to novel soft PDMS networks.…”

Section: Methodsmentioning

confidence: 99%

UV‐Cured, Platinum‐Free, Soft Poly(dimethylsiloxane) Networks

Goswami

Skov

Daugaard

2014

Chemistry A European J

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To overcome the drawbacks exhibited by platinum-catalyzed curing of silicones, photoinitiated thiol-ene cross-linking of high-molecular-weight poly(dimethylsiloxane) (PDMS) prepolymers has been investigated as a pathway to novel soft PDMS networks, based on commercially available starting materials was developed. Through a fast and efficient two-step cross-linking reaction highly flexible PDMS elastomers were prepared.

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Photocrosslinking of Silicones. Part 13. Photoinduced Thiol-Ene Crosslinking of Modified Silicones

Cited by 32 publications

References 20 publications

3D Printing Amorphous Polysiloxane Terpolymers via Vat Photopolymerization

3D Printing Amorphous Polysiloxane Terpolymers via Vat Photopolymerization

Sunlight‐Induced Cross‐Linked Luminescent Films Based on Polysiloxanes and d‐Limonene via Thiol–ene “Click” Chemistry

UV‐Cured, Platinum‐Free, Soft Poly(dimethylsiloxane) Networks

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