Synthesis of well-defined 4-miktoarm star quarterpolymers (4μ-SIDV) with four incompatible arms: Polystyrene (S), polyisoprene-1,4 (I), poly(dimethylsiloxane) (D), and poly(2-vinylpyridine) (V)

Three 4-miktoarm star quarterpolymers (4μ-SIDV), where S is polystyrene (PS), I polyisoprene1,4 (PI), D poly(dimethylsiloxane) (PDMS), and V poly(2-vinylpyridine) (P2VP), were synthesized by anionic polymerization high-vacuum techniques. 4-(Dichloromethylsilyl)diphenylethylene (DCMSDPE), a dual-functionality compound with two SiCl groups (linking agent) and a nonhomopolymerizable double bond (diphenylethylene), was used as the nodule for the incorporation of the four incompatible arms. The synthetic approach involves selective replacement of the two chlorines of DCMSDPE with PI and PDMS by titration with the corresponding living chains, addition of the third arm PSLi to the in-chain double bond of the PI/PDMS intermediate, and finally polymerization of 2VP from the newly formed anionic site to create the fourth arm. Careful extraction/fractionation of the reaction products led to 4μ-SIDV stars with high molecular weight/compositional homogeneity, as proved by size exclusion chromatography, membrane osmometry, two-angle laser light scattering, and NMR spectroscopy. Differential scanning calorimetry (DSC) measurements confirmed the incompatibility of at least the three arms (P2VP and PS have about the same glass transition temperature, T_g).