The First Synthesis of Periodic and Alternating Glycopolymers by RAFT Polymerization: A Novel Synthetic Pathway for Glycosaminoglycan Mimics

This study concerned the controlled synthesis of periodic glycopolymers by reversible addition-fragmentation chain transfer (RAFT) copolymerization. To this end, maltose- and lactose-substituted vinyl ethers (MalVE and LacVE, respectively) and maltose-substituted maleimide (MalMI) were newly synthesized. RAFT copolymerization of MalVE and ethyl maleimide (EtMI) (monomer feed ratio: MalVE:EtMI = 1:1) afforded periodic glycopolymers (poly(MalVE-co-EtMI)) consisting of major parts of alternating structure (-(MalVE-EtMI)n-) and a small part of consecutive sequences of EtMI (–EtMI-EtMI-). Occurrence of the latter sequences was caused by the homopolymerizability of maleimide under the present polymerization condition, and the formation of the consecutive sequences of EtMI was successfully suppressed by varying the monomer feed ratio. RAFT copolymerization of LacVE and EtMI was also found to proceed and similarly yielded periodic glycopolymers (poly(LacVE-co-EtMI)). Moreover, RAFT copolymerization of LacVE and MalMI (monomer feed ratio: LacVE:MalMI = 1:1) was performed to give copolymers (poly(LacVE-co-MalMI)) having composition ratio of LacVE/MalMI ≈ 36/64. The resultant periodic glycopolymers poly(MalVE-co-EtMI) and poly(LacVE-co-EtMI) were subjected to lectin binding assay using concanavalin A and peanut agglutinin, exhibiting the glycocluster effect. Moreover, these glycopolymers obtained from the copolymerization of VE and MI were found to be non-cytotoxic.

Self-doped N-4-sulfopropylaniline–3, 4-ethylenedioxythiophene copolymers

Polymerization of N-4-sulfopropylaniline with 3,4-ethylenedioxythiophene (EDOT) in several molar ratios using ammonium persulfate yielded copolymers (PPrSO3H) consisting of N-4-sulfopropylaminophenylene (unit A) and 3,4-ethylenedioxythiophene-2,5-diyl (unit B). The corresponding copolymers (PBu) consisting of N-butylaminophenylene (unit C) and unit B were synthesized by the reaction of N-butylaniline and EDOT. The content of units A, B, and C in the copolymers depended on the monomer feed ratio. The ultraviolet–visible spectrum of PPrSO3H exhibited absorption peaks at approximately 420 nm and above 850 nm assignable, respectively, to polaron and bipolaron bands. The copolymers were subjected to electrochemical oxidation, which was dependent on the contents of units A and C. The electrical conductivity of PPrSO3H was found to be higher than that of PBu.

Electrochemical behavior and conductivity measurements of electropolymerized selenophene-based copolymers

Electrochemical copolymerization of selenophene and thiophene was performed at a constant electrode potential. The obtained homopolymer films and copolymers were studied and characterized with cyclic voltammetry and conductivity measurements, from which conductivity values around 13.35 S · cm-1 were determined. The influence of the applied electropolymerization potential and the monomer feed ratio of selenophene and thiophene on the copolymers properties was investigated. The obtained copolymers showed good stability of the redox activity in an acetonitrile-based electrolyte solution. At higher polymerization potentials and at higher concentrations of thiophene in the feed, more thiophene units were incorporated into the copolymer chain. The conductivities of the copolymers were between those of homopolymers, implying that oxidation of both monomers was possible and the copolymer chains might accordingly be composed of both selenophene and thiophene units.

Avoiding compositional drift during the RAFT copolymerization of N-(2-hydroxypropyl)methacrylamide and N-acryloxysuccinimide: towards uniform platforms for post-polymerization modification

Compositionally uniform copolymers: avoiding compositional drift during RAFT copolymerization by controlling monomer feed ratio and conversion.

Polymerization of Lactide Catalyzed by Diketiminato Iron (II) Alkoxide Complex

Lactide polymerization were carried out by using diketiminato iron (II) alkoxide complexes HC(C(CH3)N-2,6-iPr2C6H3)2FeOiPr as catalyst. The iron (II) alkoxide complex bearing bulky isopropyl ortho substituents showed moderate activity for the rac-lactide polymerization, and gave the polylactide (PLA) with high molecular weight. In the microstructures of polymers generated with the iron (II) catalyst, no stereoslective polymerization of rac-lactide has been detected. Results have shown that the conversion of lactide depend on the iron complex/monomer feed ratio and the reaction temperature.