Di n butylmagnesium

PS-b-P4VP diblock copolymers were synthesized by sequential living anionic polymerization (Supplementary Fig. 34)^{49 (link)}. The solvent used for polymerization was tetrahydrofuran (THF), purified over sodium metal, and titrated with sec-butyl lithium (s-BuLi, Sigma-Aldrich, USA, 1.4 M solution in cyclohexane). Styrene was purified over a column filled with aluminum oxide and subsequently distilled from di-n-butyl magnesium (Sigma-Aldrich, USA, 1.0 M solution in heptane). 4-Vinylpyridine (4VP) was distilled under reduced pressure after being treated twice with ethylaluminium dichloride (Sigma-Aldrich, USA, 1 M in n-hexane). The polymerization of purified styrene was initiated by s-BuLi in THF at −78 °C for approximately 2 h. A 5 ml aliquot was collected from the reactor and terminated with degassed methanol for ¹H NMR and GPC analysis of PS. Afterwards, the purified 4VP was added to the reactor via a syringe and polymerized onto the living polystyrene for approx. 14 h. The polymerization was terminated with degassed methanol/acetic acid (90/10 by volume, v/v). After the removal of THF under reduced pressure and precipitation in water, the PS-b-P4VP diblock copolymers were obtained.

Monomers (Sigma-Aldrich) were purified with either n-butyllithium (Sigma-Aldrich) (isoprene, 1,3-butadiene, and ethylene oxide) or di-n-butylmagnesium (Sigma-Aldrich) (styrene). Organic solvents were used directly from a solvent drying system (JC Meyer Solvent Systems). The Monomers isoprene, 1,3-butadiene, and styrene were initiated using sec-butyllithium (Sigma-Aldrich). Potassium naphthalenide solutions used for the poly(ethylene oxide) polymerizations were prepared 24 h before the initiation of the polymerization. The nuclear magnetic resonance (NMR) experiments were performed on an Avance AV3HD 500 NMR spectrometer (Bruker) at room temperature. All the obtained spectra were calibrated according to the residual solvent peak. The size-exclusion chromatography (SEC) experiments were performed on an EcoSEC HLC-8320GPC (Tosoh Bioscience) equipped with a DAWN multi-angle static light scattering (SLS) detector (Wyatt Technology).
Mono-hydroxyl functionalized PEO, diblock copolymers SO, BO and IO were synthesized via standard anionic polymerization^{69 (link)}. Triblock copolymers SOS, BOB and IOI were synthesized by terminating the corresponding diblock copolymers with the coupling agent α,αʹ-dibromo-p-xylene^{70 (link)}. All the polymers were characterized with SEC and ¹H NMR (see detailed data in supporting information).