Synthesis of Organosilicon Monomers
May 17, 2023
A new type of polysilicone cheese containing methyl, phenyl, and ethoxy groups was synthesized using four organosilicon monomers.
Step 1: Acidification, hydrolysis, and polycondensation of the mixture of methyl and phenyl chlorosilanes. According to R/Si=1.60, Ph/CH3=0 Calculate by adding four types of organosilicon monomers, namely dimethyldichlorosilane, dimethyltrichlorosilane, diphenyldichlorosilane, and diphenyltrichlorosilane, to a total of 181 6g was mixed with xylene to form a 42% solution. Add 256g of industrial ethanol and 452g of water to the reaction flask. At 25 ° C and constant stirring, drop the xylene solution of the silicone monomer into a reaction flask, add it after 3 hours, and then react for 3.5 hours. Allow to stand, remove the acidic water from the lower layer, wash the upper solution with warm water until neutral, and then filter.
Step 2: Concentrate polysilicyl. Quickly evaporate the filtered polysilicone cheese into organic solvent at a temperature not higher than 120 ° C and a vacuum of 0.067 MPa, and concentrate until no organic solvent is evaporated. A white viscous liquid of 165g is obtained, with a density of 1 1513, Shanghai 0474.9mPa • s.
Use it to modify DPP epoxy resin (a condensation polymer of dipentadiene phenol and epichlorohydrin), which is an amber transparent brittle solid at room temperature with a softening point of 37 9 ° C, epoxy value 1.3 equivalent per gram, organic chlorine value 0.03 equivalent per kilogram, inorganic chlorine value 0 002 equivalent/kg, average molecular weight Ml538) epoxy resin 6g ground and dissolved in cyclohexanone 5 66g. Dissolve 40g of ethoxy, aryl, methyl, and phenyl polysilicone obtained from the above method into dimethyl toluene 11 In 64g. Then add these two solutions and Zn2+catalyst to the reaction bottle, which is equipped with a stirrer and a steaming device. The mixture was continuously stirred at l80 ° C for reaction. The alcohol, water, and a small amount of solvent generated during the reaction are evaporated. The reaction time is 6.45h. After the reaction is completed, use a circulating water pump to depressurize and evaporate the solvent at 160 ° C, and then use an oil pump at 160 ° C/O Under 0013MPa, the solvent was evaporated to dryness, and the modified resin A was obtained as a brownish red solid 19 59, epoxy value 0.225 equivalent/kg, average molecular weight M is 78130.
After modification, the glass transition temperature, thermal decomposition starting temperature T, and thermal decomposition peak temperature Tox of DPP all increased by about 60 ° C, indicating a significant improvement in heat resistance after modification. Modified products not only have the characteristics of strong adhesion, low shrinkage, and good stability, but also have high temperature resistance and oxidation resistance. Especially suitable for use as insulation materials and heat-resistant and moisture-proof coatings.
The curing study of modified resin A showed that the selection of different curing agents had a great impact on the curing rate and curing degree, and the reaction activity was MDA>ODE>OBA>AAB>ODDS, because the electron density on the nitrogen atom of MDA was the largest, and the reaction activity was high. The research results were consistent with the theoretical prediction. In addition, research on the silicone epoxy resin system has shown that it has low-temperature curing performance.
Due to the introduction of - Si O soft chains, the glass transition temperature (stone) of the modified resin should decrease, which is indeed the case. However, if rigid and polar groups are introduced, or hydrogen bonds are formed, resulting in a decrease in the proportion of single bonds that can be rotated internally on the chain, the ear will actually increase. At the same time, the thermal decomposition temperature (stone) of the modified resin has also increased, and some are quite significant. The epoxy value used by the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences is 0 41 ~O. 47. The epoxy resin CE-6101 with a light base value of 0.06 and an average molar mass of 370g/mol has a condensation reaction with an average molar mass of 50000g/mol of terminated polydimethylfolium oxide. Under the catalysis of organotin salts, the light terminated organosilicon directly reacts with the light base in the epoxy resin to form a Si-0-C bond. The transmission electron microscopy images of the modified resin show a two-phase separation structure, with a blurry interface between the two phases; An interpenetrating network transition layer is formed between the dispersed organic silicon phase and the matrix epoxy resin, thereby improving the compatibility between the two. With the increase of terminated polydimethylsiloxane in the modified resin, the surface energy decreases and the hydrophobicity improves. The thermogravimetric data shows that the heat resistance of modified resins is higher than that of unmodified resins. This is due to the high bond energy of the Si-0 bond on the main chain of the light terminated polydimethylsiloxane molecule, and the enhanced interaction between the two phases through the interpenetrating network transition layer. Chemical modification of bisphenol A type epoxy resin with diphenylsilanediol resulted in a yield of 1 t µ
A new type of epoxy resin with good heat resistance, water resistance, and mechanical properties, which can be used for a long time at 250 ° C. Moreover, most researchers have used polydimethylsiloxane and bisphenol A epoxy resin for copolymerization modification.
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