Liquid polyoctahedral silsesquioxanes as an effective and facile reinforcement for liquid silicone rubber

Abstract

Acrylo polyoctahedral silsesquioxanes (POSS), a liquid POSS derivative with reactive C=C double bond, is used to modify addition‐cured liquid silicone rubber (LSR) as an effective nanofiller for the first time. Significant enhancements on mechanical properties are obtained. With addition of only 1.5 parts per hundred rubbers (phr) of acrylo POSS to fumed silica‐strengthened silicones, the Young's modulus and ultimate tensile strength are increased by 432% and 66%, respectively, and the hardness of resulting LSR composites is improved as well. Proton nuclear magnetic resonance and Fourier transform infrared spectroscopies prove the efficient hydrosilylation between Acrylo POSS and hydrosiloxane directly. The thermal stability and morphology investigations also confirm that POSS is covalently incorporated into the network of silicone rubber. The increment of crosslink density is proved by extraction and swelling experiment and dynamic mechanical analysis. It can be envisioned that this simple and effective method could help produce high performance silicone rubber composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46996.

Reliable Condensation Curing Silicone Elastomers with Tailorable Properties

“…The concentration of the unreacted cross-linker decreased over time, reaching 0 wt% after 17 days as additional cross-linker domains were created. Since silsesquioxanes are generally known to be self-reinforcing cross-linkers [16][17][18][19][20][21], (QM OEt ) 8 cross-linker domains are expected to have a positive effect on elastomer film strength. The amounts of unreacted PDMS and (QM OEt )8 over time were calculated from 1 H-NMR spectra ( Figure A3), and the results are summarized in Figure 7.…”

A facile approach to prepare cage‐ladder‐structure phosphorus‐containing amino‐functionalized POSS for enhancing flame retardancy of epoxy resins

“…[7][8][9] However, when the content of POSS is high, POSS tends to agglomerate because of its high concentration or poor compatibility with the matrix, which deteriorates the mechanical properties of the polymer composites. [10][11][12] Fina 13 and Lichtenhan 14 reported that cage-ladderstructure was beneficial to disperse POSS into the polymer matrices. In our previous study, a novel cage-ladderstructure phosphorus-containing polyhedral oligomeric silsesquinoxanes (CLEP-DOPO-POSS) ( Figure 1) was successfully synthesized, due to its cage-ladder-structure and reactive epoxy group, CLEP-DOPO-POSS could be homogeneously dispersed in the EP matrix.…”

“…The introduction of DOPO into POSS to prepare phosphorus‐silicon synergistic FRs has been proven effective in the flame retardation of many polymer systems, such as EPs and polycarbonates 7–9 . However, when the content of POSS is high, POSS tends to agglomerate because of its high concentration or poor compatibility with the matrix, which deteriorates the mechanical properties of the polymer composites 10–12 …”

Cage–ladder‐structure, phosphorus‐containing polyhedral oligomeric silsesquinoxanes as promising reactive‐type flame retardants for epoxy resin

“…In general, at low loadings, POSS can improve the mechanical properties of polymer composites. However, at high loadings, POSS begins to agglomerate because of its high concentration or poor compatibility with the polymer matrix; this deteriorates the mechanical properties of the polymer composites . Fina et al .…”