Synthesis of arborescent polystyrene by “click” grafting

Abstract

A method was developed for the synthesis of arborescent polystyrene by “click” coupling. Acetylene functionalities were introduced on linear polystyrene (Mn = 5300 g/mol, Mw/Mn = 1.05) by acetylation and reaction with potassium hydroxide, 18‐crown‐6 and propargyl bromide in toluene. Polymerization of styrene with 6‐tert‐butyldimethylsiloxyhexyllithium yielded polystyrene (Mn = 5200 g/mol, Mw/Mn = 1.09) with a protected hydroxyl chain end. Deprotection, followed by conversions to tosyl and azide functionalities, provided the side chain material. Coupling with CuBr and N,N,N′,N″,N″‐pentamethyldiethylenetriamine proceeded in up to 94% yield. Repetition of the grafting cycles led to well‐defined (Mw/Mn ≤ 1.1) polymers of generations G1 and G2 in 84% and 60% yield, respectively, with Mn and branching functionalities reaching 2.8 × 106 g/mol and 460, respectively, for the G2 polymer. Coupling longer (Mn = 45,000 g/mol) side chains with acetylene‐functionalized substrates was also examined. For a linear substrate, a G0 polymer with Mn = 4.6 × 105 g/mol and Mw/Mn = 1.10 was obtained in 87% yield; coupling with the G0 (Mn = 52,000 g/mol) substrate produced a G1 polymer (Mn = 1.4×106 g/mol, Mw/Mn = 1.38) in 28% yield. The complementary approach using azide‐functionalized substrates and acetylene‐terminated side chains was also investigated, but proceeded in lower yield. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1730–1740

Synthesis of Silsesquioxanes with Substituted Triazole Ring Functionalities and Their Coordination Ability

“…Due to the interesting photoelectronic properties of SQs-based systems with aryl-triazole groups, they could be possibly used as luminescent materials with enhanced thermal resistance [ 29 , 41 , 43 , 44 , 45 ]. One of the promising branches of their application is materials chemistry, e.g., as polymers or dendrimers modifiers/synthons [ 30 , 39 , 42 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. They may be also found in macromolecular SQs-based surfactants of amphiphilic and self-assembly or encapsulation properties [ 31 , 55 , 56 ].…”

Azide- and Fluorine-Containing Polystyrenes as Potential ″Phosphine Sponges″ Based upon Staudinger Reactions: Application to the Phase Transfer Activation of Grubbs’ Catalyst

“…Considering the many types of azide-containing polymers noted in the introduction, − it is surprising that so few attempts have been made to carry out Staudinger reactions, one of the most characteristic transformations of non-polymeric organic azides. The only examples of which we are aware are shown in Figure .…”

“…Indeed, a variety of polymers with pendant azide groups in the repeat unit have been prepared. − For example, the copolymer of 2,3,4,5,6-pentafluorostyrene and 4-azido-2,3,5,6-tetrafluorostyrene has been reported. ,, Surprisingly, when this project was initiated, none of these had ever been used for Staudinger reactions, although the ready reactivity of polymer-based azide groups had been established in click [3 + 2] cycloadditions with alkynes. − …”