Using the Diels−Alder (DA) “click chemistry” strategy between anthracene and maleimide functional groups, two series of well-defined polystyrene-g-poly(ethylene glycol) (PS-g-PEG) and polystyrene-g-poly(methyl methacrylate) (PS-g-PMMA) copolymers were successfully prepared. The whole process was divided into two stages:  (i) preparation of anthracene and maleimide functional polymers and (ii) the use of Diels−Alder reaction of these groups. First, random copolymers of styrene (S) and chloromethylstyrene (CMS) with various CMS contents were prepared by the nitroxide-mediated radical polymerization (NMP) process. Then, the choromethyl groups were converted to anthryl groups via the etherifaction with 9-anthracenemethanol. The other component of the click reaction, namely protected maleimide functional polymers, were prepared independently by the modification of commercially available poly(ethylene glycol) (PEG) and poly(methyl methacrylate) (PMMA) obtained by atom transfer radical polymerization (ATRP) using the corresponding functional initiator. Then, in the final stage PEG and PMMA prepolymers were deprotected by retro-Diels−Alder in situ reaction by heating at 110 °C in toluene. The recovered maleimide groups and added anthryl functional polystyrene undergo Diels−Alder reaction to form the respective (PS-g-PEG) and (PS-g-PMMA) copolymers. The graft copolymers and the intermediates were characterized in detail by using 1H NMR, GPC, UV, fluorescence, DSC, and AFM measurements.

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Macrophotoinitiators containing thioxanthone (TX) moieties as side chains were synthesized by using "double click chemistry" strategy; combining in-situ 1,3-dipolar azide-alkyne [3 + 2] and thermoreversible Diels-Alder (DA) [4 + 2] cycloaddition reactions. For this purpose, thioxanthone-anthracene (TX-A), N-propargyl-7-oxynorbornene (PON), and polystyrene (PS) with side-chain azide moieties (PS-N 3 ) were reacted in N,N-dimethylformamide (DMF) for 36 h at 120 °C. In this process, PON acted as a "click linker" since it contains both protected maleimide and alkyne functional groups suitable for 1,3-dipolar azide-alkyne and Diels-Alder click reactions, respectively. This way, the aromacity of the central phenyl unit of the anthracene moiety present in TX-A was transformed into TX chromophoric groups. The resulting polymers possess absorption characteristics similar to the parent TX. Their capabilities to act as photoinitiator for the polymerization of monoand multifunctional monomers, namely methyl methacrylate (MMA) and 1,1,1-tris(hydroxymethyl)propane triacrylate (TPTA) were also examined.