Synthesis Of Polydimethylsiloxane Under Microwave Irradiation And Application For Hair Care

In this paper, smaller hydrodynamic radius of microemulsion with narrower distribution was prepared under microwave irradiation, and high molecular weight with narrower distribution of polydimethylsiloxane (PDMS) was polymerizated.The polysiloxane microemulsion was prepared by emulsion polymerization of octamethylcyclotetrasiloxane (D₄) under microwave irradiation with using dodecyl benzene sulfonic acid (DBSA) as catalyst and the sodium dodecyl benzene sulfonate (SDBS) and polyethylene glycol octyl phenylether (OP-10) as emulsifier. Compared with conventional heating method, the hydrodynamic radius of colloidal particle prepared under microwave irradiation was smaller, its distribution was narrower; the molecular weight of PDMS was higher, it distribution was narrower. The effect of microwave power on the polymerization was studied. The result shows that higher microwave power leads to smaller hydrodynamic radius of colloidal particle and higher conversion of D₄.The polysiloxane microemulsion prepared via anionic ring-opening polymerization of octamethylcyclotetrasiloxane (D₄) under microwave irradiation.The effect of the content of catalyzer, emulsifiers and D₄ on the preparation of silicone microemulsion was discussed and optimized. The optimized raw material configuration is that the content of D₄, DBSA,SDBS, OP-10 are 15 %, 3 %, 4 %, 2 % of the mass of microemulsion, respectively. The research of polymerization kinetics of silicone microemulsion under microwave irradiation was carried out and the result shows that the higher temperature and more content of catalyzer are favorable to speeding up conversion of D₄. Then, the effect of content of catalyzer, reaction time, reaction temperature was studied. The results show that when the content of DBSA is 3 %, the molecular weight of PDMS is highest; longer reaction time is favorable to increase molecular weight of PDMS and widen its distribution; higher reaction temperature is favorable to decrease molecular weight of PDMS and narrow its distribution. The polysiloxane microemulsion prepared first at 90°C then lower. Compared with at 30°C, the conversion of D₄ was higher. Compared with at 90°C, the molecular weight of PDMS was higher.Shampoos were compound with synthetical polysiloxanes under microwave irradiation and conventional heating and commercial polysiloxane, respectively, compared with commercial shampoos by evaluating their foaming abilities, dry and wet combing forces and the depositions of silicone on hair.