Controlled Synthesis Of Polymethylsesquioxane Microspheres

During the middle of the 20 th century,J.F.Hyde from Corning Class in the United States achieved a significant milestone in material science by synthesizing the first organic silicon material in the world,i.e.,silicone glass fiber cloth.This breakthrough brought organic silicon formally into the realm of material science.Among various organic silicon materials,Polyorganic Sesquioxane(PSQ)microspheres represent a typical example.PSQ microspheres have been utilized in various fields,such as biomedical sciences,catalysis,photoelectricity,and environmental science,due to their low dielectric constant,high heat insulation,hydrophobicity,and chemical stability.Among the PSQ microspheres,Polymethylsesiloxane(PMSQ)microspheres are the most widely employed.These microspheres not only exhibit good chemical stability and hydrophobic properties,but they also possess desirable features such as being odorless,non-toxic,physiologically inert,and having excellent air permeability.Moreover,PMSQ microspheres demonstrate a certain degree of lubricity,anti-ultraviolet radiation capability,anti-static properties,and are non-irritating to the skin,while providing reliable protection.However,the performance requirements for microspheres vary across different applications.Unfortunately,current synthesis methods cannot adequately control the density,particle size,oil absorption,and other key properties of PMSQ microspheres.This paper has employed response surface methodology to design experiments based on optimal design methods and theories and combined with the synthesis mechanism of PMSQ microspheres.Mathematical models have been established by summarizing and analyzing the experimental data to achieve the controllable synthesis of PMSQ microspheres with different properties.The specific research contents of this study are as follows:(1)Screening of precursor and catalyst types and preparation methods: Methyl trimethoxy-silane(MTMS)was chosen as the precursor,and the control variable method was used to preliminarily screen the preparation methods and catalyst types.The results showed that the two-step sol-gel method was better than the one-step sol-gel method as it allowed for the separation of hydrolysis and polymerization steps and resulted in better morphology of the PMSQ microspheres.When sodium hydroxide was used as a catalyst,the product PMSQ microspheres showed good sphericity and uniform particle size distribution.(2)Screening of reaction conditions: Orthogonal experiments were conducted to preliminarily screen the reaction conditions,including precursor concentration,catalyst dosage,reaction temperature,and hydrolysis agitation rate.The results showed that the sphericity,particle size distribution,and surface smoothness of the product PMSQ microspheres were relatively excellent at a reaction temperature of 50℃.(3)In order to further investigate the influence of different synthesis parameters on the properties of PMSQ microspheres,a series of experiments were designed using response surface methodology(RSM)in combination with mathematical modeling.The parameters considered included precursor concentration,catalyst dosage,hydrolysis stirring rate,and hydrolysis time.The results showed that the precursor concentration was the main factor affecting the yield,density,and oil absorption of the PMSQ microspheres,while the amount of catalyst added was the main factor affecting the particle size.The interaction between the reaction conditions and the performance of the microspheres also showed a significant level,indicating that the relationship was not simply linear.A mathematical model of PMSQ microsphere yield,particle size,oil absorption value,density,and process parameters was established based on the experimental data.The regression models were found to be significant,indicating that they accurate indicating that they accurately reflected the relationship between each factor and the response value.(4)In order to explore the stability of the preparation method,the experiments were scaled up to produce PMSQ microspheres with excellent performance and good morphology.It was found that the particle size,bulk density,oil absorption rate,and yield of the PMSQ microspheres obtained by the scaled-up experiment were almost consistent with those obtained by the low-dose experiment,indicating that the method had good stability and could be used for batch production of PMSQ microspheres.(5)In addition to synthesizing PMSQ microspheres with good properties,efforts were also made to minimize waste and promote sustainability.Experimental liquid waste was recovered and reused by adjusting the p H to the same as that of distilled water and then using it to synthesize PMSQ microspheres by the two-step sol-gel method.The characterization of the resulting microspheres showed that they had specific performance and were successfully prepared using this method.