Solvothermal Alcoholysis Method for Recycling High-Consistency Silicone Rubber Waste

Abstract

In this work, we investigated the potential use of high-consistency silicone rubber (SR), which is a synthetic solid material used in numerous industrial applications, to produce a range of liquid alkoxysiloxane derivatives R­(OSiMe2) x OR, with x = 1 (P 1 ), 2 (P 2 ), 3 (P 3 ), and 4 (P 4 ). We describe a simple and convenient solvothermal alcoholysis method for the chemical recycling of post-consumer SR in the presence of fatty alcohols under catalyst-free or catalytic conditions. This process proceeds easily both without and with a catalyst. Alkali-metal aryloxides supported by a methylsalicylato ligand (MesalO) gave the highest conversions of SR to products P 1 –P 4 . Magnesium and zinc aryloxides enabled efficient conversions of products P 2 –P 4 to P 1 . Binary metal catalysts of general formula [M2M′2(MesalO)6] (M = Mg or Zn; M′ = Li, Na, or K), which had a combination of the catalytic properties shown by alkali-metal aryloxides and magnesium/zinc aryloxides, were produced and used to synthesize P 1 –P 4 . The results show that magnesium–sodium/potassium aryloxides had the best catalytic activities. Their use led to the formation of two dominant products, namely, P 1 and P 2 , with conversion yields of 79 and 17%, respectively. Particular emphasis is placed on the operating conditions and high activity of the catalyst used. Key factors that affect the catalytic activity and reaction mechanism are also highlighted.

Use of heterometallic alkali metal–magnesium aryloxides in ring-opening polymerization of cyclic esters

“…It plays an important role in the ROP of cyclic esters and the alcoholysis of high consistency silicone rubber. 36…”

“…It plays an important role in the ROP of cyclic esters and the alcoholysis of high consistency silicone rubber. 36 The representative 1 H NMR spectrum in C 6 D 6 of the resulting PLLA showed resonance signals at 4.26, 2.58, and 1.39 ppm from the CH, OH, and CH 3 groups of hydroxyl end units, the protons of the CH and CH 3 groups of the main chain at 5.06 and 1.48 ppm, and resonances for the alkyl protons of the hexadecyl ester group at 4.01, 1.15 and 0.77 ppm (Fig. 10).…”

“…CCDC 2123619-2123623 † contains the supplementary crystallographic data for this article.Synthesis of[Mg 2 Li 2 (MesalO) 6 ] (1),[Mg 2 Na 2 (MesalO) 6(THF) x ] for x = 2 or 4 (2), [Mg 2 K 2 (MesalO) 6 (THF) 4 ] (3) Structural, spectroscopic, and analytical data for 1-3 have been published in ref 36…”

Microwave‐assisted alcoholysis of silicone rubber waste with geraniol for effective elastomer damping

“…Recently, Petrus et al [ 33 ] pioneered a solvothermal alcoholysis method for recycling crosslinked silicone rubber in the presence of fatty alcohols. Several alkoxysilane derivatives with tunable molecular weights were obtained by regulating the catalyst type and content and the reaction temperature and time.…”

Polyoxometalate-like structure of new potassium triphenylsiloxides: [K6(OSiPh3)6(C3H7OH)(H2O)]·2C6H5CH3 and [K6(OSiPh3)6(H2O)2]

“…Due to the absence of an energetically-accessible vacant d manifold (McGeary et al, 1991), ISSN 2053ISSN -2296 they can lead to homo-and heterometallic siloxide coordination compounds (Sobota et al, 2000(Sobota et al, , 2002Coan et al, 1991;Willauer et al, 2020a,b). For instance, such complexes can play the role of molecular precursors for mixed-metal solid-state materials, such as binary metal silicates (Petrus et al, 2019).…”