Precision Synthesis of ω-Branch, End-Functionalized Comb Polystyrenes Using Living Anionic Polymerization and Thiol–Ene “Click” Chemistry

Abstract

A combination of living anionic polymerization and thiol−ene "click" chemistry provides an efficient and convenient method for synthesis of well-defined comb polystyrenes with precisely controlled architecture details and a wide selection of functionalities. ω-(p-Vinylbenzyl)polystyrene macromonomer was synthesized by sec-butyllithium-initiated polymerization of styrene followed by termination with 4-vinylbenzyl chloride (VBC). For the synthesis of α-4-pentenyl-ω-(p-vinylbenzyl)polystyrene macromonomer, an unsaturated initiator, 4-pentenyllithium, was used followed by termination with VBC. To ensure successful living anionic polymerization of macromonomers, impurities present in the macromonomers and glass reactors were readily removed by titration with excess sec-butyllithium initiator right before initiation, resulting in polymacromonomers with controlled M n (74 000, 130 000 g/mol) and narrow M w /M n . Living anionic copolymerization of mixtures of both types of macromonomers yielded a well-defined comb-shape precursor with controlled fractions of ω-vinyl branch end groups, which were subsequently subjected to facile and efficient functionalization by photoinitiated thiol−ene "click" reactions with diverse functional groups (−OH, −CO 2 H, and −C 8 F 17 ). Characterization by NMR, SEC, and MALDI-TOF mass spectrometry established their chemical structures and chain-end functionalities, which indicates precisely defined comb polystyrenes with controlled degrees of functionalization.

Directional Self‐Assembly of Fluorinated Star Block Polymer Thin Films Using Mixed Solvent Vapor Annealing

“…We note that all BPs have trithiocarbonate (ttc) end groups, thus, there was no variability in end‐group functionality for the XRR samples. This consistency is important as end‐group chemistry is well known to impact the phase behavior of the BP . We also note that the ttc end groups are stable at 170 °C as reported in the literature .…”

The Effect of Phenyl Content on the Liquid Crystal-Based Organosilicone Elastomers with Mechanical Adaptability

“…It can be seen from Figure 1 b that the grafting efficiency of MBB is almost 100% because the vinyl peak of MBB completely disappears. The thiol-ene click reaction is relatively convenient and efficient [ 32 , 33 ]. According to the following equation: the number of grafting MBB = 10 × (2 × I 5 /I 2 ), I 5 and I 2 is the ratio of integrated intensity of peak 5 to that of peak 2 in the 1 H NMR spectrum of Figure 1 b, we can conclude that the number of grafting MBB was approximately six.…”

Effect of Aromatic Co‐Solvents on the Efficiency of Atom Transfer Radical Coupling Reactions of Fluorinated and Non‐Fluorinated Vinyl Aromatic Polymers

“…Styrenic monomers represent an important class of readily polymerizable alkenes amenable to cationic, anionic, and radical polymerization methods . Reversible deactivation radical polymerization (RDRP) is especially well‐suited to employ styrenes, with abundant literature examples of nitroxide mediated polymerization (NMP), reversible addition−fragmentation chain transfer (RAFT), and several flavors of atom transfer radical polymerization (ATRP) all leading to polystyrene (PS) of controllable molecular weight and well defined end groups.…”