A photoresponsive azobenzene-bridged cubic silsesquioxane network

Guo, Sufang; Okubo, Tatsuya; Kuroda, Kazuyuki; Shimojima, Atsushi

doi:10.1007/s10971-016-4074-4

Cited by 9 publications

(7 citation statements)

References 44 publications

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“…An alternative and solution to this problem could be the use of cheaper, silsesquioxane resins which would retain the capability of functionalization and would have well-defined, 3D moieties in their structure. However, most of the cross-linked structures based on silsesquioxane cores do not have functional groups capable of producing chemical bonds to polymer, in contrast to the cage-like silsesquioxane derivatives [21][22][23][24][25][26][27][28][29][30][31][32]. The covalent incorporation of reactive silsesquioxane monomers into polymers is the greatest advantage of the proposed fillers.…”

Section: Introductionmentioning

confidence: 99%

Polyurethane composites based on silsesquioxane derivatives of different structures

Szołyga

Dutkiewicz

Marciniec

2018

J Therm Anal Calorim

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A series of siloxane-silsesquioxane resins with Q 8 structures, as network nodes containing reactive Si-H groups in the siloxane backbone, connecting silsesquioxane moieties, were prepared in a hydrolytic condensation process and successfully functionalized by hydrosilylation of allyl alcohol. The proposed material being an alternative to the well-defined silsesquioxanes has been characterized and used for preparation of a series of polyurethane (PU)-based composites by simple reaction of 3-hydroxypropyl groups of siloxane-silsesquioxane resin with 1,6-diisocyanatohexane and subsequently with 1,6-hexanediol to get polyurethane composite. A series of composites based on PU and octakis(3-hydroxypropyldimethylsiloxy)octasilsesquioxane were prepared in the same manner to investigate the influence of the filler amount (1, 3 or 5%) and its structure on thermal properties of the obtained materials.

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Section: Introductionmentioning

confidence: 99%

Polyurethane composites based on silsesquioxane derivatives of different structures

Szołyga

Dutkiewicz

Marciniec

2018

J Therm Anal Calorim

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“…The allyloxy‐azo di‐functional cross‐linker used in this paper has been used in previously published investigations, [ 61 ] however an examination of the monomers base photophysical properties has not been well established on their own. UV–vis spectroscopy was used to better quantify actuation efficiency, and the quantum yield of the isomerization of the cross‐linker.…”

Section: Resultsmentioning

confidence: 99%

“…Over the past few decades, silicon chemists have shown great interest in the preparation of responsive siloxane gel systems; most notably using liquid crystal or polymeric elastomers. [ 56–61 ] The most famous example of this was achieved by Finkelmann et al. which used a methylsiloxane polymer functionalized with mesogens that could be mechanically aligned in a two‐step synthetic process.…”

Section: Introductionmentioning

confidence: 99%

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Photoreversible Loading and Unloading of Q–Silsesquioxane Dynamic Network Sponges

Furgal

2021

Adv Funct Materials

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The synthesis and mechanical properties of photoswitchable silsesquioxane/azobenzene hybrid 3D‐polymers (“dynamic sponges”) are presented and discussed. The hybrid is capable of extensive macroscopic movement, and overcomes previously problematic crosslink locking issues. A hydride‐functionalized Q‐type silsesquioxane (Q8M8H) is reacted with di‐allyloxyazobenzene using hydrosilylation methods. The properties of the resulting materials are controlled via careful choice of starting material ratios and solvent, leading to gels or films. Both morphologies show pronounced photoresponsive behavior in and on the surfaces of different solvents. Photoactuation is tracked by microscopy, dynamic mechanic analysis, and UV–vis spectroscopy. The gel system has a porous structure similar to a sponge. It undergoes shrinkage in volume by 18.3% in toluene under UV irradiation, and shows excellent recovery to the swollen state after irradiation with visible light. These novel photodynamic materials offer reversible modulus switching from 160 kPa in the swollen state to 500 kPa in the “wrung‐out” sponge. The sponges can engage in uptake and release of a range of substances (i.e., reversible hydrophobic sponging), with overall performance determined by solvent specific quantities such as polarity and size. Such behavior gives these materials high potential for soft robotics applications and great promise as reusable environmental remediators.

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“…such as in biology or environmental remediation. as capture and release agents [2,17,[37][38][39]. These functionalities may include hydrophilic groups, amino-acids and reversible chemistries such as "click" or complexation ligands [40][41][42][43][44].…”

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confidence: 99%

R-Silsesquioxane-Based Network Polymers by Fluoride Catalyzed Synthesis: An Investigation of Cross-Linker Structure and Its Influence on Porosity

Furgal

2020

Materials

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Silsesquioxane-based networks are an important class of materials that have many applications where high thermal/oxidative stability and porosity are needed simultaneously. However, there is a great desire to be able to design these materials for specialized applications in environmental remediation and medicine. To do so requires a simple synthesis method to make materials with expanded functionalities. In this article, we explore the synthesis of R-silsesquioxane-based porous networks by fluoride catalysis containing methyl, phenyl and vinyl corners (R-Si(OEt) 3 ) combined with four different bis-triethoxysilyl cross-linkers (ethyl, ethylene, acetylene and hexyl). Synthesized materials were then analyzed for their porosity, surface area, thermal stability and general structure. We found that when a specified cage corner (i.e., methyl) is compared across all cross-linkers in two different solvent systems (dichloromethane and acetonitrile), pore size distributions are consistent with cross-linker length, pore sizes tended to be larger and π-bond-containing cross-linkers reduced overall microporosity. Changing to larger cage corners for each of the cross-linkers tended to show decreases in overall surface area, except when both corners and cross-linkers contained π-bonds. These studies will enable further understanding of post-synthesis modifiable silsesquioxane networks.Materials 2020, 13, 1849 2 of 13 of reaction solvent and water content in modifying the overall pore size distributions of a single cross-linker system [29]. Though many reports speculate that the pore sizes obtained in sol-gel reactions are directly related to the bridging groups used, especially for rigid spacers [2,26,[30][31][32], we found that multiple pore size distributions (0.5 to 100 nm) could be obtained by simply changing the reaction solvent for the same bridge. For example, dichloromethane (DCM) favored micropores on the order of 1.2 nm and gel particles, while changing the reaction solvent to acetonitrile (ACN) gave pores centered around 3 nm and favored global gelation of the entire system. All the synthesized materials favored non-polar solvents as expected for organogels based on networked silsesquioxanes.Though high porosity materials with static or non-functionalizable pores are useful in many applications [33][34][35][36], it is often desirable to impart additional functionality to these materials for many specialized uses. such as in biology or environmental remediation. as capture and release agents [2,17,[37][38][39]. These functionalities may include hydrophilic groups, amino-acids and reversible chemistries such as "click" or complexation ligands [40][41][42][43][44]. Many researchers have been working on methods to synthesize active silsesquioxane-based networks, albeit primarily through preformed cage methods. In terms of preformed cage systems, Ervithayasuporn et al. have developed a recyclable methacrylate-POSS (polyhedral oligomeric silsesquioxanes) porous network which can efficiently bind Pd and acts as a catalyst f...

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A photoresponsive azobenzene-bridged cubic silsesquioxane network

Cited by 9 publications

References 44 publications

Polyurethane composites based on silsesquioxane derivatives of different structures

Polyurethane composites based on silsesquioxane derivatives of different structures

Photoreversible Loading and Unloading of Q–Silsesquioxane Dynamic Network Sponges

R-Silsesquioxane-Based Network Polymers by Fluoride Catalyzed Synthesis: An Investigation of Cross-Linker Structure and Its Influence on Porosity

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