Nitrone Mediated Coupling of Hyperbranched Polymer Radicals

Abstract

The coupling of hyperbranched polychloromethylstyrene (PCMS) radicals with nitrone is studied in this work. Hyperbranched PCMS radicals are generated by a redox reaction of terminal chloride groups with Cu(I)Cl. The molecular weight data show that nitrone mediated radical coupling of PCMS is a kind of step polymerization. The molecular weights of the coupled products in a fixed coupling reaction time increase as the contents of nitrone increase in a wide concentration range, whereas are less affected by the content of CuCl. FTIR and NMR spectra prove the formation of alkoxyamine in the mid‐chains arising from nitrone‐mediated coupling. The nitrone‐coupled hyperbranched polymers show the birefringent property if being watched in a crossed polarizing microscope. The intrinsic viscosity data imply that the nitrone‐coupled hyperbranched polymers in solution behave like rod‐like structures. These nitrone‐coupled hyperbranched polymers are thermodegradable. This kind of cylindrical polymers with highly branched substructures may find important application as anisotropic monomolecular gels or molecular reinforcement, catalyst hosts, etc.

Reversible Surface Engineering via Nitrone-Mediated Radical Coupling

“…51 Initially, nitrones were assessed as control agents in enhanced spin-capturing polymerization 29,52−54 and further as coupling reagent in nitrone-mediated radical coupling (NMRC) that allows for the introduction of a new midchain alkoxyamine functionality, 55,56 e.g., to construct dendrimers, 57 star polymers, 58 and other architectures. 59,60 More recently, NMRC has also been used to couple polymers derived from reverse iodine-transfer polymerization, further underpinning that any precursor of nonpersistent radicals can be employed. 61 We herein exploit both key features of NMRC, i.e., dynamic covalent reversibility and postcoupling NMP, for surface grafting.…”

“…Even though dynamic covalent exchange/reversibility and postcoupling block copolymerization are excellent features of alkoxyamines obtained from NMRC, nitrones received the most attention in synthetic organic chemistry for their use in [2 + 3] cycloadditions − and as radical spin-traps − yet only little in the context of polymer chemistry . Initially, nitrones were assessed as control agents in enhanced spin-capturing polymerization ,− and further as coupling reagent in nitrone-mediated radical coupling (NMRC) that allows for the introduction of a new midchain alkoxyamine functionality, , e.g., to construct dendrimers, star polymers, and other architectures. , More recently, NMRC has also been used to couple polymers derived from reverse iodine-transfer polymerization, further underpinning that any precursor of nonpersistent radicals can be employed …”

Structural and hydrodynamic characteristics of polystyrene synthesized in the presence of conjugated dinitrones

“…[23][24][25] High-molecular-weight AAs based on spin traps with symmetric structure can also be obtained using radical trap-assisted atom transfer radical coupling (RTA-ATRC). [26][27][28][29][30][31][32][33][34] The technique involves the synthesis of a polymer with a particular structure and MW characteristics in the ATRP regime followed by coupling of highmolecular-weight radicals mediated by nitrones or nitroso compounds in the presence of a catalytic system based on transition metals.…”

“…For instance, star-shaped, H-shaped, cyclic, dendritic, and other polymeric products were synthesized in the SFRP, ESCP, and RTA-ATRC regimes in the presence of functional nitrones. 9, [30][31][32][33][34][35] Note that the development of new methods for the synthesis of branched polymers is to a great extent due to the diff erence of the physicochemical properties of these polymers from those of their linear analogues. Branched polymers possess a number of unique properties and have a wide variety of applications including biomedical ones.…”