Multifunctional Homopolymers: Postpolymerization Modification via Sequential Nucleophilic Aromatic Substitution

Abstract

Despite recent progress for efficient and precise synthesis of functional polymers, few reports describe postpolymerization functionalization strategies for the controlled incorporation of multiple pendent groups per repeat unit. Cyanuric chloride, or 2,4,6-trichloro-1,3,5-triazine (TCT), offers a facile method to introduce distinct pendent functionalities. An acrylamide monomer containing a triazine ring with two electrophilic sites was prepared from TCT and polymerized via reversible addition−fragmentation chain transfer (RAFT) polymerization. Subsequent nucleophilic aromatic substitution reactions using a combination of amine and thiol nucleophiles introduced two functionalities into each repeat unit of the RAFTderived polymers. The success of each postpolymerization modification reaction was confirmed by 1 H NMR spectroscopy and size-exclusion chromatography, and small molecule model studies corroborated the high chemoselectivity of the nucleophilic aromatic substitution reactions. This postpolymerization modification strategy based on TCT enables a facile and efficient synthesis of multifunctional homopolymers.

Synthesis of Multifunctional Homopolymers through Using Thiazolidine Chemistry and Post‐Polymerization Modification

“…This strategy circumvents possible adverse side reactions that can occur with certain functional groups during the polymerization . We have previously studied the functionalization and application of chain‐end and side‐chain heterodifunctional polymers utilizing 2,4,6‐trichloro‐1,3,5‐triazine and benzotrifuranone . In those examples, the reactive polymers contained two electrophilic sites that enabled modification via two sequential reactions with distinct nucleophiles to afford multifunctional polymers.…”

Orthogonal Click Postfunctionalization of Alternating Copolymers Prepared by Nitroxide‐Mediated Polymerization

“…The resulting poly(HFIPA‐ alt ‐OVE) was orthogonally postfunctionalized via radical thiol–ene click reaction and subsequent amidation . It is well known that the properties of polymers can be altered significantly by chemical postfunctionalization and numerous recent reports deal with the modification of polymers by thiol click chemistry, Cu‐catalyzed alkyne–azide click reaction (CuAAC), amidation reactions, and many others, including combinations thereof. Our conceptual approach introduced allowed for preparation of a small library of alternating copolymers using a single type of parent copolymer and diversifying subsequent orthogonal postmodification.…”

Medium effect (water versus MeCN) on reactivity and reaction pathways for the SNAr reaction of 1-aryloxy-2,4-dinitrobenzenes with cyclic secondary amines

“…Even a cursory look at the literature shows the versatility of S N Ar reactions, which have been employed recently in at least one step of the reported syntheses of: fluorescent teraaza [8]circulenes, 8 2-amino-and 2-arylazoanulenes, 9 aromatic ring substituted porphyrins, 10 substituted amidoazopyridines from perfluorinated pyridine, 11 various potentially therapeutic substituted pyrimidines 12,13 and dipyridylazepines, 14 and benzimidazole N-oxides. 15 The reactions of water-soluble polymers end-group substituted with electron-deficient aromatics have been studied 16,17 and in post-polymerization functionalization, poly(acrylamide) bearing pendant 3,5-dichloro-2,4,6-triazinyl groups can react via S N Ar reaction to yield a wide range of modified poly(acrylamide)s. 18 Some significant potential environmental remediation protocols also rely on nucleophilic aromatic displacement. [19][20][21]…”