Chinese Journal of Applied Chemistry ›› 2015, Vol. 32 ›› Issue (5): 527-534.DOI: 10.11944/j.issn.1000-0518.2015.05.140326

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Synthesis of Linear Oligomer of Dimethyltetrasiloxane

CAO Dua, XIA Yonga, YAO Hongtaoa, QI Zhengjiana, *, SUN Yub, LI Fengfub   

  1. aCollege of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
    bJiangsu Maysta Chemical Co. Ltd., Nanjing 210046, China
  • Received:2014-09-19 Revised:2014-12-04 Accepted:2015-01-28 Online:2015-05-05 Published:2015-05-05
  • Contact: QI Zhengjian
  • Supported by:
    Supported by Jiangsu Province Science and Technology Support Program(No;BE 2012810), the Fundamental Research Funds for the Central Universities(No;CXLX13_106)

Abstract:

Linear dimethyltetrasiloxane(MD4M) was synthesized using octamethylcyclotetrasiloxane(D4) and hexamethyldisiloxane(MM) as raw materials and solid super acid(SA) TiO2/SO42- as catalyst. The influence of reaction time, reaction temperature, amount of relative molecular mass modifier(MM) and catalyst dosage on the degree of polymerization and the content of the product was studied by uniform design experiments and single factor experiments. Experiment results showed that the optimum reaction conditions are as follows:the molar ratio of octamethylcyclotetrasiloxane to hexamethyldisiloxane) is 0.75:1, the catalyst loading is 2%(mass fraction) of the total reactants, the reaction temperature is 100 ℃ and the reaction time is 7 h. The reaction conversion is 87% and the yield of MD4M is 16.8% which is 1.6% more than the sulfuric acid system. The catalyst(SA) can be recycled more than 3 times without the loss of its catalytic activity. The macro-kinetics model of the ring-opening polymerization of D4 with solid super acid as the heterogeneous catalyst was also created using the quasi-homogeneous system.

 

Key words: solid super acid, dimethyltetradesiloxane, dynamics

CLC Number: