| 초록 |
Energy calculation using non-local DFT relative to the adsorption of several substituted 1,3-diethers on the (100) and (110) lateral cuts of MgCl2 are presented. Independent of the substituents, coordination of the diethers on the (110) cut is always preferred. In our previous study, it is calculated that atactic and isotactic fractions of polypropylene obtained by these catalytic systems are prevailingly produced by Ti catalytic species adsorbed on (110) and (100) cuts, respectively. Therefore it is suggested that the role of 1,3-diethers is the prevention of the formation of non-stereospecific active site on (110) cut. The energy difference favoring the diether coordination on the (110) cut depends on the substituents on carbon 2 of the 1,3-alkoxypropane skeleton. These calculated energy differences are able to rationalize the observed dependence of the stereoregulating ability for propylene polymerization on the chemical structure of the 1,3-diethers. |
