Synthesis and characterization of rigid functional anionic polyelectrolytes: Block copolymers and star homopolymers

Abstract

Seven cyclolinear polymers bearing the tertiary‐butyl α‐(hydroxymethyl)acrylate (TBHMA) ether dimer were prepared using reversible addition–fragmentation chain transfer (RAFT) polymerization. Of the seven polymers, five were cyclolinear homopolymers of the TBHMA ether dimer with different degrees of polymerization, one was an “arm‐first” star homopolymer, and the other was an amphiphilic linear copolymer based on the positively ionizable hydrophilic 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and the TBHMA ether dimer. For comparison, two more polymers were prepared using RAFT polymerization where the TBHMA ether dimer was replaced by tertiary‐butyl methacrylate (tBuMA). In particular, an amphiphilic linear DMAEMA–tBuMA diblock copolymer and a tBuMA arm‐first star homopolymer were also synthesized. All polymers were characterized in terms of their molecular weights and composition using gel permeation chromatography and 1H NMR spectroscopy, respectively. Subsequently, the tertiary‐butyl groups of the TBHMA ether dimer units and those of the tBuMA units were cleaved by hydrolysis to yield carboxylic acid groups. The successful removal of the tertiary‐butyl groups was confirmed using 1H and 13C NMR and attenuated total reflectance‐Fourier transform infrared spectroscopies. The hydrolyzed (co)polymers exhibited pK values of the carboxylic acid groups of around 4.5, and glass transition temperatures, Tg, of around 200 °C, which were 50 °C higher than those of their nonhydrolyzed precursors. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Phase behavior of rigid, amphiphilic star polymers

“…Our results can be experimentally tested by using short-chain diblock stars with high bending rigidity. Possible candidates are block-copolymer-graed nanoparticles 63,64 for which the chain rigidity emerges either by the short chain length or, e.g., by graing rigid polymers such as functionalized polyelectrolytes 65 or polypeptides 66 on nanoparticles.…”

Probing the Inhomogeneous Charge Distribution on Annealed Polyelectrolyte Star Polymers in Dilute Aqueous Solutions

“…By comparing the integration of the proton peaks from the pyridyl groups in the monomer units and from the Boc-amino group, the M n was estimated to be 60000 and 62000 for the P2VP stars with central and terminal amino groups, respectively, implying an average of eight arms per P2VP star (Figures B and S3). We cautiously expect that the polydispersity of M w / M n = 1.30, possibly due to the distribution of arm numbers in one P2VP star, could have little effect on the conformational dynamics according to previous reports of linear P2VP chains and branched PEs in the similar polydispersity range. − After purification, the amino groups in both stars were deprotected for reactions to attach a fluorophore, either Alexa Fluor 488 (Alexa488) or pH-sensitive Oregon Green 488 (OG488), to the targeted central or terminal location. The successful reactions were confirmed by FCS (Figure A) and UV–vis spectroscopy (Supporting Information, Figure S4 and Table S1).…”

Synthesis and characterization of double hydrophilic block copolymers containing semi‐rigid and flexible segments

“…These precisely defined, semi‐rigid polyelectrolytes afford pH and salt‐responsive copolymers, likely due to the semi‐rigid polymer backbone. Semi‐rigid polymers are uncommon compared to rigid polyelectrolytes, and incorporating the stilbene‐containing copolymers into more sophisticated polymer architectures, such as block copolymers, enables investigation into the effects of the semi‐rigid polymer segments on the polyelectrolyte solution properties.…”