Metal-Free Synthesis of Poly(silyl ether)s under Ambient Conditions

Sample, Caitlin S.; Lee, Sang‐Ho; Bates, Morgan W.; Ren, Jing; Lawrence, Jimmy; Lensch, Valerie; Gerbec, Jeffrey A.; Bates, Christopher M.; Li, Shaoguang; Hawker, Craig J.

doi:10.1021/acs.macromol.8b02741

Cited by 29 publications

(33 citation statements)

References 42 publications

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“…In particular, developing Si-HBPs via simple, rapid and mild synthetic procedures is highly desirable. The Piers-Rubinsztajn (P-R) reaction, namely the condensation of alkoxysilanes with hydrosilanes, has rapidly developed since it was found in the 1990s [22,23], because this strategy is mild and provides a possibility for the controlled or precise synthesis of silicones, including small molecules, linear polymers, and crosslinked materials [24][25][26][27][28][29][30][31]. For example, the P-R coupling reactions of various organic tris(dimethylsiloxy)silane and trialkoxysilane compounds can generate a series of cyclic polysiloxanes with cyclotetrasiloxane subunits in a simple one-step synthesis [32].…”

Section: Introductionmentioning

confidence: 99%

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Hyperbranched Polycarbosiloxanes: Synthesis by Piers-Rubinsztajn Reaction and Application as Precursors to Magnetoceramics

Zhang

Xue

et al. 2020

Polymers

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Silicon-containing hyperbranched polymers (Si-HBPs) have drawn much attention due to their promising applications. However, the construction of Si-HBPs, especially those containing functional aromatic units in the branched backbones by the simple and efficient Piers-Rubinsztajn (P-R) reaction, has been rarely developed. Herein, a series of novel hyperbranched polycarbosiloxanes were prepared by the P-R reactions of methyl-, or phenyl-triethoxylsilane and three Si-H containing aromatic monomers, including 1,4-bis(dimethylsilyl)benzene, 4,4 -bis(dimethylsilyl)-1,1 -biphenyl and 1,1 -bis(dimethylsilyl)ferrocene, using B(C 6 F 5 ) 3 as the catalyst for 0.5 h at room temperature. Their structures were fully characterized by Fourier transform infrared spectroscopy, 1 H NMR, 13 C NMR, and 29 Si NMR. The molecular weights were determined by gel permeation chromatography. The degrees of branching of these polymers were 0.69-0.89, which were calculated based on the quantitative 29 Si NMR spectroscopy. For applications, the ferrocene-linked Si-HBP can be used as precursors to produce functional ceramics with good magnetizability after pyrolysis at elevated temperature.

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Section: Introductionmentioning

confidence: 99%

“…, 26.6 • , 30.1 • , 33.1 • , 35.6 • , and 62.6 • , etc., are associated with the reflections of SiO 2 , SiC, C, Fe 3 O 4 , and Fe 2 O 3 (ICDD data file 46-1045, 29-1129,26-1076, 89-0691 and 33-0664). These results reveal that the hyperbranched polymer has been successfully pyrolyzed and transformed into a ceramic.…”

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confidence: 99%

Hyperbranched Polycarbosiloxanes: Synthesis by Piers-Rubinsztajn Reaction and Application as Precursors to Magnetoceramics

Zhang

Xue

et al. 2020

Polymers

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“…Silyl ethers, (R’O) n SiR 4– n , are hydrolytically degradable groups that have been investigated recently by different research groups for the production of biocompatible materials. − The major hydrolysis products of the moisture-sensitive Si–O bonds in silyl ethers are silanols and alcohols, both of which are relatively nontoxic. The hydrolysis products also do not considerably change the pH of the surrounding environment.…”

Section: Introductionmentioning

confidence: 99%

Degradable Silyl Ether–Containing Networks from Trifunctional Thiols and Acrylates

et al. 2020

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The purpose of this study was the synthesis of novel degradable polymer-based devices capable of releasing an encapsulated agent in a controlled manner with specific interest for use as drug delivery materials. Base-catalyzed thiol Michael additions between trithiols and triacrylates containing silyl ether groups were exploited to prepare a series of degradable cross-linked networks. Disodium fluorescein was loaded as a hydrophilic drug surrogate inside the networks, and the degradation of the networks and the release of dye were monitored. The networks were characterized by Fourier transform infrared spectroscopy, and their thermal and mechanical properties were investigated through thermogravimetric analysis and dynamic mechanical analysis. The effects of the monomer structure on degradation, release behavior, and thermal properties were investigated. The networks prepared from more sterically hindered silyl ether monomers exhibited decreased rates of degradation and correspondingly slower release of encapsulated disodium fluorescein dye. The results suggest that the characteristics of the networks can be fine-tuned by manipulation of the group attached to the Si atom in the silyl ether monomers.

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“…25 While previous work has focused on small-molecule transformations, B(C 6 F 5 ) 3 -catalyzed hydrosilylation has been employed in polymer chemistry to produce a variety of Si−O-containing polymers, including polysiloxanes via the oligomerization of dihydrosilanes, 26,27 poly-(silphenylenesiloxane)s via the polycondensation of dihydrosilanes and dialkoxysilanes or dihydroxysilanes, 28,29 and poly(silyl ethers) via the polycondensation of dihydrosilanes and dihydroxysilanes, 30 dienes, 31 or diketones. 32 The use of B(C 6 F 5 ) 3 in vulcanization, however, has been limited because previous examples are based on the reaction of hydrosilanes with alkoxysilanes or other nonatom-efficient partners, 33−37 with the evolved gaseous byproducts used to produce foams or removed prior to full cure. In this work, the borane-catalyzed hydrosilylation of commercially available α-diketones and linear siloxanes is shown to lead to rapid, efficient vulcanization of silicones with no byproducts (Scheme 1).…”

Section: ■ Introductionmentioning

confidence: 99%

Metal-Free Room-Temperature Vulcanization of Silicones via Borane Hydrosilylation

Sample

Lee

et al. 2019

Macromolecules

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Vulcanization of silicone networks from commercially available linear poly(dimethyl-co-methylhydro)siloxane (PMHS) and α-diketones was achieved using metal-free borane hydrosilylation at room temperature. The Lewis acid catalyst, tris(pentafluorophenyl)borane (B(C6F5)3), efficiently cross-linked PMHS at minimal catalyst loadings (200–1000 ppm) to produce polymer networks with mechanical properties, thermal stability, and optical clarity rivaling that achieved from traditional platinum catalysis. Variation of the starting PMHS structure is shown to influence the final characteristics of the network. Increasing molar mass of the PMHS chain results in a higher thermal decomposition temperature, while increasing mole fractions of Si–H moieties along the backbone increase the cross-linking density and the attendant Shore hardness. The degradation behavior of the networks was investigated, with the borane-vulcanized samples showing rapid dissolution upon exposure to acid and high stability to neutral and basic conditions. Functional networks bearing halide and vinyl groups could also be prepared via a preliminary reaction of PMHS with an appropriate monoketone, providing a general and versatile strategy for network derivatization with the potential for postvulcanization functionalization being subsequently demonstrated via thiol–ene click chemistry.

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Metal-Free Synthesis of Poly(silyl ether)s under Ambient Conditions

Cited by 29 publications

References 42 publications

Hyperbranched Polycarbosiloxanes: Synthesis by Piers-Rubinsztajn Reaction and Application as Precursors to Magnetoceramics

Hyperbranched Polycarbosiloxanes: Synthesis by Piers-Rubinsztajn Reaction and Application as Precursors to Magnetoceramics

Degradable Silyl Ether–Containing Networks from Trifunctional Thiols and Acrylates

Metal-Free Room-Temperature Vulcanization of Silicones via Borane Hydrosilylation

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