Synthesis and characterization of copolymers with the same proportions of polystyrene and poly(ethylene oxide) compositions but different connection sequence by the efficient Williamson reaction

Abstract

The AB type diblock PS‐b‐PEO and ABA type triblock PS‐b‐PEO‐b‐PS copolymers containing the same proportions of polystyrene (PS) and poly(ethylene oxide) (PEO) but different connection sequence were synthesized and investigated. Using the sequential living anionic polymerization and ring‐opening polymerization mechanisms, diblock PS‐b‐PEO copolymers with one hydroxyl group at the PEO end were obtained. Then, using the classic and efficient Williamson reaction (realized in a ‘click’ style), triblock PS‐b‐PEO‐b‐PS copolymers were achieved by a coupling reaction between hydroxyl groups at the PEO end of PS‐b‐PEO. The PS‐b‐PEO and PS‐b‐PEO‐b‐PS copolymers were well characterized by 1H NMR spectra and SEC measurements. The critical micelle concentration (CMC) and thermal behaviors were also investigated by steady‐state fluorescence spectra and DSC, respectively. The results showed that, because the PEO segment in triblock PS‐b‐PEO‐b‐PS was more restricted than that in diblock PS‐b‐PEO copolymer, the former PS‐b‐PEO‐b‐PS copolymer always gave higher CMC values and lower crystallization temperature (Tc), melting temperature (Tm) and degree of crystallinity (Xc) parameters. © 2015 Society of Chemical Industry

Design, Synthesis and Characterization of 1,2-Phenylenediamine Functionalized Poly (Maleic Anhydride-alt-Vinyl Acetate) as a Potential New Bioactive Formulation

“…3). CH2 signals were detected at 1.85 and ~2.8 ppm ascribes to VA moiety [39,40], and -CH3 protons were appeared at ~ 1.1 ppm attributed to the VA [41]. The characteristic protons associated with the aromatic rings of 1,2-PDA groups were observed to form a broad peak at about at 6.3 and 6.4 ppm (Fig.…”

MeNPF4.5 Improves Cassava Nitrogen Use Efficiency and Yield by Regulating Nitrogen Uptake and Allocation

“…Nitrate reductase (NR) activity was measured using a kit from the Nanjing Jian Cheng Bioengineering Institute (Nanjing, China), according to the manufacturer’s instructions. The activities of glutamine synthetase (GS), glutamine oxoglutarate aminotransferase (GOGAT), and glutamate dehydrogenase (GDH) were determined using the method described by Huang et al (2015) .…”

A Powerful Strategy for Synthesizing Block Copolymers via Bimetallic Synergistic Catalysis

“…[26][27][28] In the former procedure, a hydroxyl group needs to be installed at the chain end of polyolefin, thus enabling the initiation of the anionic ring-opening polymerization of epoxides. [29,30] In the latter procedure, polyolefin and polyether segments, which are terminated with "click reaction" group couples, require to be prepared before the coupling process. [31] To date, none of the polyolefin-b-polyether block copolymers have been directly synthesized from the copolymerization of epoxides and olefins.…”

“…It is hoped that the construction of polyolefin‐ b ‐polyether from epoxides and olefins will afford high‐performances and attractive applications. These block copolymers have been accessed via multistep procedures, which include the step‐feeding of olefins and epoxides, and the coupling of polyolefin and polyether segments via “click reaction.” [26–28] In the former procedure, a hydroxyl group needs to be installed at the chain end of polyolefin, thus enabling the initiation of the anionic ring‐opening polymerization of epoxides [29,30] . In the latter procedure, polyolefin and polyether segments, which are terminated with “click reaction” group couples, require to be prepared before the coupling process [31] .…”