Study On The Synthesis And Performances Of Non-ionic Polyether Modified Trisiloxanes Surfactant

Surfactants are provided with extensive applications in science research and industry,especially agriculture fields, due to their highly influencing interface properties. The use ofagricultural surfactants to reduce pesticide residues, save water and reduce labor intensity isgreat significance, particularly, for China which is a big agricultural country. Non-ionicpolyether modified trisiloxanes surfactant is a kind of agricultural surfactants, with excellentperformance. Due to the research of this kind of surfactants has been started relatively late,the most of this products are imported in China. To change this situation, the paper targetedhas pertinently synthetized non-ionic polyether modified trisiloxanes surfactant, which can beused for agricultural surfactant.First, The systhesis of1,1,1,3,5,5,5-Heptamethyltrisiloxane(MDHM) from hexamethydi-siloxane(MM) and high hydrogen-containing polyhydrosiloxane (DH) was catalyzed by strongacidic cation ion exchange resin. Its structure was verified by fourier transform infraredspectroscopy and proton nuclear magnetic resonance. By gas chromatography internalstandard method, a standard curve was obtained by fitting a MDHM’s linear equation:y=1.5887x, relative mass correction factor fdodecane,MDHM=1.5887, correlation coefficientR2=0.9926; and MDHM purity≥97%in distillation product, detected by GC. The systhesis ofMDHM was optimized after applying Response Surface Methodology (RSM). It was foundthat the optimal conditions at which the highest yield of MDHM (40.62%) was obtained, beingin well agreement with the predicted value (41.23%), were as follows: the reaction mass ratioof m(MM):m(DH)=1:13.45, the amount of solid acid catalyst was7.09%, and reactiontemperature and time were62.5℃and10h, respectively. Furthermore, the research ofpolymerization kinetics under different temperatures was carried out and the results show thatthe optimal temperature and time are right. Contrast with the corresponding literature findings,the yield of MDHM was effectively improved by the optimization method, and the filteredsolid acid catalyst could be effectively reused more than five times.Secondly, The systhesis of non-ionic polyether modified trisiloxanes surfactant(NTS)from MDHM and polyoxyethylene alkyl allyl ethers(PE-38), with average EO chain length of7-8and average molecular weight of380, was catalyzed by Karstedt catalyst under N2with no solvent. Its structure was verified by fourier transform infrared spectroscopy and protonnuclear magnetic resonance. The systhesis of NTS was optimized after applying ResponseSurface Methodology (RSM). It was found that the optimal conditions at which the averagesurface tension (18.417mN/m) repeated three times was obtained, being in well agreementwith the predicted value (18.177mN/m), were as follows: the reaction mass ratio of n(C=C):n(Si-H)＝0.93, the amount of catalyst was6.4ppm, and reaction temperature and time were94℃and2h, respectively. Many indicators of the product were tested, such as the contactangle of0.1wt%NTS aqueous solution, kinematic viscosity, cloud point, CMC, adsorptioncapacity and adsorption layer, the average area occupied by each molecule and otherindicators. The hydrolysis of the aqueous solution of NTS at pH4,7and10also was studied,and found that the product under acidic and alkaline conditions was stable for about30days,under a neutral condition was stable for about60days.Finally, NTS was used as adjuvant of herbicides, philoxeroides was selected as thecontrolling target, and the specific herbicide philoxeroides20%Starane was selected as acomplex mix of pesticides. Through a series of treatment found that the groups which addingNTS as a adjuvant were more pronounced to reduce weed plants relative water content,chlorophyll content and growth state than the groups which simply adding herbicide; andfound that the treatment of which made up by2/3of the concentration of herbicide solutionand0.05%NTS adjuvant was best for weed control by contrast. The results illustrated that theamount of herbicide could be reduced at least1/3, and the herbicidal effect could be improved,through adding0.05%NTS adjuvant. This experimental results show that non-ionicpolyether-modified trisiloxane surfactant which was synthesized by this experiment can beeffectively used as an agricultural adjuvant.