A New Methodology for the Synthesis of Star Polymers Utilizing the Reaction of Living Polymers with Alkoxysilyl-Functionalized Polymers

Abstract

A novel method for linking polymeric organolithium compounds to form heteroarm (miktoarm) star-branched polymers has been demonstrated. After functionalization of a polymeric organolithium compound with excess multifunctional chlorosilane linking agent, the resulting polymeric chlorosilyl groups were converted to methoxysilyl groups with anhydrous methanol followed by precipitation into methanol. This procedure removed excess, nonvolatile, linking agent required to prevent linking reactions. Polystyrene-b-oligo(butadienyl)lithium (PS-b-oligoBD) was functionalized with excess 1,2-bis(dichloromethylsilyl)ethane in benzene with added triethylamine to minimize linking reactions during conversion of chlorosilyl to methoxysilyl groups. Quantitative conversion and complete removal of excess linking agent were demonstrated by SEC, 1H NMR, 13C NMR, and 29Si NMR analyses. MALDI−TOF mass spectral analysis of the methoxysilyl-functionalized PS-b-oligoBD was consistent with the proposed structure and indicated the absence of side reaction products. A 4-arm, star-branched polystyrene prepared by treating methoxysilyl-functionalized PS-b-oligoBD with excess PS-b-oligoBDLi was essentially indistinguishable from an analogous polymer prepared using only 1,2-bis(dichloromethylsilyl)ethane. While the method has been demonstrated for synthesis of a 4-arm star, its use will have greatest benefit for the synthesis of higher order, multibranched, miktoarm star materials.

Effect of Butadiene End-Capping of Arms in a Star Polystyrene on Solution Properties, Bulk Dynamics, and Bulk Thermodynamic Interactions in Binary Blends

“…Styrene, benzene, and butadiene were purified as described previously. 13 1,2-Bis-(dichloromethylsilyl)ethane (DMSE) (Aldrich, 98%) was purified by distillation at 120 °C on the vacuum line. The first third of the distillate was discarded; the next third was collected, diluted with purified benzene in a drybox, ampulized, and heat-sealed on the vacuum line.…”

Effects of Branch Points and Chain Ends on the Thermodynamic Interaction Parameter in Binary Blends of Regularly Branched and Linear Polymers

“…However, the 13-end branched polymer was prepared using a recently developed methoxysilyl functionalization method. 31 All chlorides of the chlorosilyl end-functionalized precursor polymer were converted into methoxy groups in order to be able to remove the excess linking agent by precipitation. Then the methoxysilyl end-functionalized precursor polymer was reacted with excess living arm polymer.…”

“…The two precursor polymers for the 6-end and 9-end branched polymers were reacted directly with an excess of the appropriate living arm polymer. However, the 13-end branched polymer was prepared using a recently developed methoxysilyl functionalization method …”

Synthesis and Characterization of Well-Defined, Regularly Branched Polystyrenes Utilizing Multifunctional Initiators

“…It was known that the methyltrichlorosilane linking agent used to synthesize the functionalized 6-end branched polystyrene precursor and the tetrachlorosilane linking agent used to synthesize the func- tionalized 9-end branched polystyrene precursor can be easily removed by the freeze-drying method because of their low boiling points. 47 Curve (2) in Figure 2 is the SEC chromatogram of the precursor polystyrene (15) for the 6-end branched polystyrene after the chlorosilyl functionalization with methyltrichlorosilane and freezedrying. The small peak at 20.6 mL retention volume before the big peak is due to the presence of coupled precursor polymer formed during functionalization.…”