Synthesis and real-time 1 H NMR kinetic studies on the living anionic copolymerization of 4-trimethylsilylstyrene (4TMSS), an electronically intricate monomer, are reported. Statistical copolymers of 4TMSS with styrene (S) and isoprene (I) with M n up to 50 kg mol −1 were synthesized and analyzed with respect to dispersity, comonomer composition, and glass-transition temperatures, T g . Access to well-defined di-and triblock copolymers ensured comprehensive synthetic control. Real-time 1 H NMR kinetic measurements unraveled an enthralling gradient microstructure (r 4TMSS = 2.76; r S = 0.087 and r I = 3.28; r 4TMSS = 0.15) in the copolymers. The sequence distribution provided by a tandem MALDI-MS 2 study validated an enhanced reactivity of 4TMSS in comparison to styrene in cyclohexane at room temperature. Furthermore, the kinetics of 4TMSS homopolymerization revealed detailed mechanistic insights. The possibility to tailor T g and hydrophobicity of the copolymers by varying the 4TMSS content provides a promising approach to design copolymer-based materials for high-end applications, for example, in gas separation membranes.

Dedicated to Brigitte Voit on the occasion of her 60th birthdayIn-depth understanding of copolymerization kinetics and the resulting polymer microstructure is crucial for the design of materials with well-defined properties. Further, insights regarding the impact of solvents on copolymerization kinetics allows for precisely tuned materials. In this regard, in situ 1 H NMR spectroscopy enables precise monitoring of the living anionic ring-opening copolymerization (AROP) of ethylene oxide (EO) with the glycidyl ethers allyl glycidyl ether (AGE) and ethoxy vinyl glycidyl ether (EVGE), respectively. Determination of reactivity ratios reveals slightly higher reactivity of both glycidyl ethers compared to EO, emphasizing a pronounced counterion chelation effect by glycidyl ethers in AROP. Implementation of density functional theory (DFT) calculations further illustrates the complexation capability of ether-containing side groups in glycidyl ethers, in analogy to crown ethers ("crown ether effect"). Investigation of the copolymerization in i) THF-d 8 and ii) DMSO-d 6 shows an increasing disparity of reactivity ratios for both glycidyl ethers compared to EO, clearly related to decreasing solvent polarity.

The copolymerization of glycidyl cinnamate (GC) as a hitherto non-polymerizable, photoreactive epoxide structure to aliphatic polyether copolymers is described, using the monomer-activated epoxide ring-opening polymerization (MAROP). Ethoxyethyl glycidyl ether (EEGE) and GC are copolymerized employing triisobutylaluminum (i-Bu 3 Al) as a catalyst and tetraoctylammonium bromide (NOctBr 4 ) as an initiator. The amount of GC varies from 3 mol% to 100 mol%, which results in apparent molecular weights in the range of 2600 to 4600 g mol −1 and dispersities (Ð) below 1.34. Studies of the microstructure by in-situ 1 H NMR kinetics indicate a gradient-like distribution of EEGE and GC (reactivity ratios: r EEGE = 0.28; r GC = 3.6), applying the ideal copolymerization model for evaluation. A tentative explanation relies on differing bond lengths in the respective epoxide rings, as suggested by density functional theory (DFT) calculations. Mild and selective cleavage of the acetal protecting groups of EEGE is achieved using the acidic ionic resin Dowex, leaving the GC ester bonds intact (M n = 1900-3700 g mol −1 , Ð < 1.34). Thermal properties of the copolymers and the PGC homopolymer are investigated by differential scanning calorimetry (DSC). The crosslinking of P(G-co-GC) copolymers by UV irradiation allows hydrogel formation, which is confirmed by IR spectroscopy.