Nanocomposite structures of polypyrrole derivatives and poly (acrylonitrile‐co‐itaconic acid) produced by in situ polymerization as carbon nanofiber precursor

This study aimed to produce nanoparticles of poly (acrylonitrile‐co‐itaconic acid) (P (AN‐co‐IA)) containing conjugated polymers of pyrrole, N‐Methylpyrrole, 2,5‐dimethylpyrrole, and 1‐(Triisopropylsilyl)pyrrole which were synthesized by emulsion polymerization. Nanocomposite structures of P (AN‐co‐IA)/polypyrrole and polymer of pyrrole derivatives were produced via in situ polymerization, and the nanoparticle formation were followed by morphologic and ultraviolet‐visible (UV‐Vis) spectroscopic methods. Characterizations were made by Fourier transform infrared‐attenuated total reflectance (FTIR‐ATR) and Raman spectroscopy. Atomic force microscopy (AFM) was used for investigating the surface characteristics of the nanoparticles. Characterization results revealed that nanoparticles containing conjugated polymers had rougher surface than P (AN‐co‐IA) nanoparticles. It was also observed that the nanoparticles were well‐distributed although having some agglomerates. Moreover, depending on the type of monomer of conjugated polymer, the shape and size of the produced nanoparticles differed by conjunction with their polymerization rate. These findings can be used as a startup information for production of carbon nanofibers (CNFs) with desired properties after oxidation and carbonization, and as a high‐performance and cost‐effective flame and heat‐resistant material (oxidized copolymers of polyacrylonitrile nanofiber).     

Synthesis of IONP's decorated graft copolymers and study of their magnetic force–induced wastewater treatment

Our work is focused on facile synthesis and modification of amylopectin‐grafted block copolymers by using reversible addition?fragmentation chain transfer (RAFT) polymerization technique. This technique yields polymers with controlled molecular weight and low polydispersity indexes and is feasible with a wide range of monomers. Five different grades of amylopectin‐grafted polymethacrylic acid and polyacrylamide block copolymers have been synthesized via RAFT, by varying the amount of acrylamide employing amylopectin‐based macro chain transfer agent. Graft copolymers have been upgraded as smart responsive graft copolymers, through the incorporation of iron oxide nanoparticles (IONPs) via condensation reaction. The polymeric materials have been extensively characterized by energy‐dispersive X‐ray analysis, Fourier transform infrared spectroscopy, proton magnetic resonance spectroscopy, scanning electron microscopy, ultraviolet‐visible spectroscopy, gel permeation chromatography, transmission electron microscopy, thermogravimetric analysis, and X‐ray diffraction analysis. Normal and responsive graft copolymers have been studied for removal of model contaminant (kaolin), and responsive graft copolymers have been used to remove methylene blue dye (without using any adsorbent) from water by applying external magnetic field. The upgraded block copolymers have shown best performance in wastewater treatment.     

A novel molecular imprinting polymer for the selective adsorption of D-arabinitol from spiked urine

In this research, molecular imprinting polymers (MIPs) for D-arabinitol were synthesized using a bulk polymerization method through a noncovalent approach. The MIPs were prepared by using D-arabinitol as a template, acrylamide as a functional monomer, ethylene glycol dimethacrylateas cross-linker, benzoyl peroxide as an initiator and dimethyl sulfoxideas a porogen. MIPS was synthesized in several formulas with a different molar ratio of template to functional monomers and cross-linker. Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to characterize the MIPs produced. A batch rebinding assay was used to test the binding efficiency of each formula. Batch rebinding test results revealed that MIPsF3 with a molar ratio of the template: monomer and crosslinker ratio respectively (1: 4: 25) had the highest binding capacity at 1.56 mgg ^-1 . The results of isotherm adsorption showed that the MIPs produced followed the Freundlich equation with an R-value of 0.97. The MIPs produced was also selective toward its isomeric compounds (i.e. L-arabinitol, adonitol, xylitol, and glucose). The extraction efficiency of the MIPs against D-arabinitol was 88.98%.     

Flowerlike hybrid horseradish peroxidase nanobiocatalyst for the polymerization of guaiacol

In this study, the catalytic activity and stability of flowerlike hybrid horseradish peroxidase (HRP) nanobiocatalyst (HRP-Cu ²⁺ ) obtained from Cu ²⁺ ions and HRP enzyme in the polymerization reaction of guaiacol were analyzed. We demonstrated that HRP-Cu ²⁺ and hydrogen peroxide (H ₂ O ₂ ) initiator showed significantly increased catalytic activity and stability on the polymerization of guaiacol compared to that of free HRP enzyme. Poly(guaiacol) was observed with quite high yields (88%) and molecular weights (38,000 g/mol) under pH 7.4 phosphate-buffered saline (PBS) conditions at 60 °C with 5 weight% of HRP-Cu ²⁺ loading. HRP-Cu ²⁺ also shows very high thermal stability and works even at 70 °C reaction temperature; free HRP enzyme denatures at that temperature. Furthermore, HRP-Cu ²⁺ provided considerable repeated use and showed some degree of catalytic activity, even after the fourth recycle, in the polymerization of guaiacol.     

Switchable Polymerization Triggered by Fast and Quantitative Insertion of Carbon Monoxide into Cobalt–Oxygen Bonds

A strategy that uses carbon monoxide (CO) as a molecular trigger to switch the polymerization mechanism of a cobalt Salen complex [salen=(R,R)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamine] from ring‐opening copolymerization (ROCOP) of epoxides/anhydrides to organometallic mediated controlled radical polymerization (OMRP) of acrylates is described. The key phenomenon is a rapid and quantitative insertion of CO into the Co?O bond, allowing for in situ transformation of the ROCOP active species (Salen)Co^III‐OR into the OMRP photoinitiator (Salen)Co^III‐CO₂R. The proposed mechanism, which involves CO coordination to (Salen)Co^III‐OR and subsequent intramolecular rearrangement via migratory insertion has been rationalized by DFT calculations. Regulated by both CO and visible light, on‐demand sequence control can be achieved for the one‐pot synthesis of polyester‐b‐polyacrylate diblock copolymers (?<1.15).     

Living Supramolecular Polymerization of an Aza‐BODIPY Dye Controlled by a Hydrogen‐Bond‐Accepting Triazole Unit Introduced by Click Chemistry

An aza‐BODIPY dye 1 bearing two hydrophobic fan‐shaped tridodecyloxybenzamide pendants through 1,2,3‐triazole linkages was synthesized by a click reaction and characterized. ¹H NMR studies indicated that dye 1 exhibited variable conformations through intramolecular H‐bonding interaction, which is beneficial for the polymorphism of aggregation. The thermodynamic, structural, and kinetic aspect of the supramolecular polymerization of dye 1 was investigated by UV/Vis absorption spectroscopy, IR spectroscopy, AFM, TEM, and SEM. Biphasic aggregation pathways of dye 1 , leads to the formation of off‐pathway, metastable Agg. I and thermodynamically stable Agg. II with distinct H‐aggregation spectra and nanoscale morphology. The living manner of the supramolecular polymerization of dye 1 was demonstrated in seeded polymerization experiments with temperature‐modulated successive cooling–heating cycles.     

Unprecedented Sequence Control and Sequence‐Driven Properties in a Series of AB‐Alternating Copolymers Consisting Solely of Acrylamide Units

Herein, we report a method to synthesize a series of alternating copolymers that consist exclusively of acrylamide units. Crucial to realizing this polymer synthesis is the design of a divinyl monomer that contains acrylate and acrylamide moieties connected by two activated ester bonds. This design, which is based on the reactivity ratio of the embedded vinyl groups, allows a “selective” cyclopolymerization, wherein the intramolecular and intermolecular propagation are repeated alternately under dilute conditions. The addition of an amine to the resulting cyclopolymers afforded two different acryl amide units, i.e., an amine‐substituted acryl amide and a 2‐hydroxy‐ethyl‐substituted acryl amide in alternating sequence. Using this method, we could furnish ten types of alternating copolymers; some of these exhibit unique properties in solution and in the bulk, which are different from those of the corresponding random copolymers, and we attributed the differences to the alternating sequence.     

One‐Step Ring Opening Metathesis Block‐Like Copolymers and their Compositional Analysis by a Novel Retardation Technique

Using a one‐step synthetic route for block copolymers avoids the repeated addition of monomers to the polymerization mixture, which can easily lead to contamination and, therefore, to the unwanted termination of chain growth. For this purpose, monomers ( M1 – M5 ) with different steric hindrances and different propagation rates are explored. Copolymerization of M1 (propagating rapidly) with M2 (propagating slowly), M1 with M3 (propagating extremely slowly) and M4 (propagating rapidly) with M5 (propagating slowly) yielded diblock‐like copolymers using Grubbs’ first ( G1 ) or third generation catalyst ( G3 ). The monomer consumption was followed by ¹H NMR spectroscopy, which revealed vastly different reactivity ratios for M1 and M2 . In the case of M1 and M3 , we observed the highest difference in reactivity ratios (r₁=324 and r₂=0.003) ever reported for a copolymerization method. A triblock‐like copolymer was also synthesized using G3 by first allowing the consumption of the mixture of M1 and M2 and then adding M1 again. In addition, in order to measure the fast reaction rates of the G3 catalyst with M1 , we report a novel retardation technique based on an unusual reversible G3 Fischer‐carbene to G3 benzylidene/alkylidene transformation.     

Cell Engineering with Functional Poly(oxanorbornene) Block Copolymers

Cell‐based therapies are gaining prominence in treating a wide variety of diseases and using synthetic polymers to manipulate these cells provides an opportunity to impart function that could not be achieved using solely genetic means. Herein, we describe the utility of functional block copolymers synthesized by ring‐opening metathesis polymerization (ROMP) that can insert directly into the cell membrane via the incorporation of long alkyl chains into a short polymer block leading to non‐covalent, hydrophobic interactions with the lipid bilayer. Furthermore, we demonstrate that these polymers can be imbued with advanced functionalities. A photosensitizer was incorporated into these polymers to enable spatially controlled cell death by the localized generation of ¹O₂ at the cell surface in response to red‐light irradiation. In a broader context, we believe our polymer insertion strategy could be used as a general methodology to impart functionality onto cell‐surfaces.