Main-Chain and Side-Chain Sequence-Regulated Vinyl Copolymers by Iterative Atom Transfer Radical Additions and 1:1 or 2:1 Alternating Radical Copolymerization

Abstract

Main- and side-chain sequence-regulated vinyl copolymers were prepared by a combination of iterative atom transfer radical additions (ATRAs) of vinyl monomers for side-chain control and 1:1 or 2:1 alternating radical copolymerization of the obtained side-chain sequenced "oligomonomers" and vinyl comonomers for main-chain control. A complete set of sequence-regulated trimeric vinyl oligomers of styrene (S) and/or methyl acrylate (A) were first synthesized via iterative ATRAs of these monomers to a halide of monomeric S or A unit (X-S or X-A) under optimized conditions with appropriate ruthenium or copper catalysts, which were selected depending on the monomers and halides. The obtained halogen-capped oligomers were then converted into a series of maleimide (M)-ended oligomonomers with different monomer compositions and sequences (M-SSS, M-ASS, M-SAS, M-AAS, M-SSA, M-ASA, M-SAA, M-AAA) by a substitution reaction of the halide with furan-protected maleimide anion followed by deprotection of the furan units. These maleimide-ended oligomonomers were then radically copolymerized with styrene or limonene to enable the 1:1 or 2:1 monomer-sequence regulation in the main chain and finally result in the main- and side-chain sequence-regulated vinyl copolymers with high molecular weights in high yield. The properties of the sequence-regulated vinyl copolymers depended on not only the monomer compositions but also the monomer sequences. The solubility was highly affected by the outer monomer units in the side chains whereas the glass transition temperatures were primarily affected by the two successive monomer sequences.

Cu-Catalyzed Three-Component Carboamination of Alkenes

“…Furthermore, addition of these radicals to olefins is well-documented in related methodologies and in atom transfer radical polymerization (ATRP). 5,6 …”

“…Thus, a common Cu catalyst of fixed redox reactivity does not achieve high reactivity across electrophile classes. 6a Ongoing work in our laboratory aims to understand these ligand effects and to identify a general Cu catalyst for this transformation.…”

Coding and decoding libraries of sequence-defined functional copolymers synthesized via photoligation

“…Generating an ensemble of perfectly sequence-defined identical macromolecules containing exactly the same chemical information at the molecular scale—in contrast to existing avenues to disperse and irregularly coded species when compared with natural analogues—via a simple process constitutes a key technological gate for data storage, biological and material applications, yet requires reaction concepts that provide perfect yields and orthogonality under equimolar reaction conditions. Although solid-state peptide synthesis was introduced by Merrifield6—the first example of a true synthetic sequence-defined peptide—macromolecular chemists have initially focused on and developed a diverse number of solution-based polymerization strategies for imparting a certain level of control over statistical polymerization processes and exploited these for controlling the order of the building blocks (sequence-controlled polymers)7891011121314151617181920. In addition, the advent of modular synthetic strategies21222324 has contributed significantly towards achieving a high level of control over macromolecular formation processes.…”

Sequence-regulated vinyl copolymers with acid and base monomer units via atom transfer radical addition and alternating radical copolymerization

“…For the radical copolymerization of styrene and oligomonomers with a t-butyl acrylate unit (M-SA p , M-A p S) at a 1:1 feed ratio in toluene at 60 °C with AIBN, both styrene and maleimide group were consumed at nearly the same rate to yield copolymers with relatively high molecular weights (M n > 180000) similar to the previously reported unfunctionalized maleimide-ended oligomonomers and styrene. 17,18 However, radical copolymerization of the aminefunctionalized oligomonomers with styrene resulted in only low molecular weight polymers (M n = 1000-2000) in toluene and DMF at 60 °C due to irreversible chain-transfer reactions caused by the amine moiety despite their consumption at nearly the same rate. However, in a fluorinated alcohol (PhC(CF 3 ) 2 OH) with weak acidity, the alternating radical copolymerization successfully proceeded at 20 ºC with a low temperature radical azo-initiator (V-70), resulting in alternating copolymers with higher molecular weights (M n = 20000-40000).…”

“…Many approaches for controlling the monomer sequences in vinyl copolymers have been reported including copolymerization with highly selective propagation, such as alternating copolymerization, [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] template polymerization, 21-31 sequential multi block copolymerization, [32][33][34][35][36][37][38] iterative single monomer addition reactions, [16][17][18][39][40][41][42][43][44][45][46] and other polymerizations of designed monomers. 39,41,[46][47][48][49][50][51][52][53][54][55][56][57][58] However, the degree of controllability, number of controllable sequence units, and molecular weigh...…”