Preparation Of Copolymers Research Articles

Polypyrrole–polyaniline-water hyacinth leaf protein concentrate composite for the removal of Cr(VI) from aqueous solution: kinetics, isotherm and thermodynamic studies

ABSTRACT. This work focused on the extraction of “water hyacinth leaf protein concentrate” (WHLPC) and preparation of polypyrrole (PPy), polyaniline (PANI) and polypyrrole-polyaniline copolymer (PPy/PANI) coated WHLPC by in situ polymerization and investigate their application for the removal of Cr(VI) from aqueous solution. After optimizing the experimental conditions like pH, adsorbent dosage, contact time and initial concentration it was found that the kinetics and isotherm data were well fitted to the pseudo-second-order and Langmuir models, respectively. PPy/PANI/WHLPC was found to be an efficient material compared to the other polymer-coated adsorbents with maximum adsorption capacity of 230 mg/g. The presence of counter ions ((NO3-, Cl-, HPO42-, SO42+ and HCO3- ions) slightly decreases the Cr(VI) removal efficiency PPy/PANI/WHLPC. The thermodynamic study reveals that the adsorption of Cr(VI) onto PPY/PANI/WHLPC is endothermic, thermodynamically feasible, and spontaneous. In addition, reusability of the material indicated high removal efficiency for two adsorption cycles.
  
 KEY WORDS: Polypyrrole, Polyaniline, Protein concentrate, Water hyacinth, Chromium
 Bull. Chem. Soc. Ethiop. 2022, 36(3), 571-584.                                                              
 DOI: https://dx.doi.org/10.4314/bcse.v36i3.7

Synthesis and Characterization of Copolymers and Nanocomposites from Limonene, Styrene and Organomodified-Clay Using Ultrasonic Assisted Method.

In the present work, we report a simple synthesis method for preparation of copolymers and nanocomposites from limonene and styrene using clay as a catalyst. The copolymerization reaction is carried out by using a proton exchanged clay as a catalyst called Mag-H+. The effect of temperature, reaction time and amount of catalyst were studied, and the obtained copolymer structure (lim-co-sty) is characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H-NMR) and differential scanning calorimetry (DSC). The molecular weight of the obtained copolymer is determined by gel permeation chromatography (GPC) and is about 4500 g·mol−1. The (lim-co-sty/Mag 1%, 3%, 7% and 10% by weight of clay) nanocomposites were prepared through polymer/clay mixture in solution method using ultrasonic irradiation, in the presence of Mag-CTA+ as green nano-reinforcing filler. The Mag-CTA+ is organophilic silicate clay prepared through a direct exchange process, using cetyltrimethylammonuim bromide (CTAB). The prepared lim-co-sty/Mag nanocomposites have been extensively characterized by FT-IR spectroscopy, X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM). TEM analysis confirms the results obtained by XRD and clearly show that the obtained nanocomposites are partially exfoliated for the lower amount of clay (1% and 3% wt) and intercalated for higher amounts of clay (7% and 10% wt). Moreover, thermogravimetric analysis (TGA) indicated an enhancement of thermal stability of nanocomposites compared with the pure copolymer.

Subcritical Water as a Pre-Treatment of Mixed Microbial Biomass for the Extraction of Polyhydroxyalkanoates.

Polyhydroxyalkanoate (PHA) recovery from microbial cells relies on either solvent extraction (usually using halogenated solvents) and/or digestion of the non-PHA cell mass (NPCM) by the action of chemicals (e.g., hypochlorite) that raise environmental and health hazards. A greener alternative for PHA recovery, subcritical water (SBW), was evaluated as a method for the dissolution of the NPCM of a mixed microbial culture (MMC) biomass. A temperature of 150 °C was found as a compromise to reach NPCM solubilization while mostly preventing the degradation of the biopolymer during the procedure. Such conditions yielded a polymer with a purity of 77%. PHA purity was further improved by combining the SBW treatment with hypochlorite digestion, in which a significantly lower hypochlorite concentration (0.1%, v/v) was sufficient to achieve an overall polymer purity of 80%. During the procedure, the biopolymer suffered some depolymerization, as evidenced by the lower molecular weight (Mw) and higher polydispersity of the extracted samples. Although such changes in the biopolymer’s molecular mass distribution impact its mechanical properties, impairing its utilization in most conventional plastic uses, the obtained PHA can find use in several applications, for example as additives or for the preparation of graft or block co-polymers, in which low-Mw oligomers are sought.

Synthesis and characterization of star-shaped block copolymers composed of poly(3-hydroxy octanoate) and styrene via RAFT polymerization

This study investigated a macro reversible addition fraction chain transfer (RAFT) agent based on three-arm hydroxylated star-shaped poly(3-hydroxy octanoate). The utilization of this star-shaped poly(3-hydroxy octanoate) macro-RAFT agent in the RAFT process resulted in efficient control in the preparation of star-shaped block styrene copolymers. Poly(3-hydroxy octanoate) (PHO) was reacted with diethanol amine (DEA) in order to obtain three-arm hydroxylated poly(3-hydroxy octanoate) (PHO-DEA). A carboxylic acid-functionalized RAFT agent (2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid) was reacted with the PHO-DEA in order to obtain a star-shaped PHO macro-RAFT agent (PHO-R2). A series of AB3 type PHO-polystyrene (PHO-PS) star-shaped block copolymers were obtained via the polymerization of styrene (S) using the PHO-R2 in toluene at 80 °C. The RAFT polymerization was seen to obey the polymerization kinetics of controlled free radical polymerization. The plasticizing effect of the PHO soft segments was influenced by the glass transition temperature (Tg) of polystyrene. This was clearly observed in the block copolymers. Moreover, it was clear that this plasticizing effect disappeared in the block copolymers as a result of the increase in polymerization time. The molar masses of the obtained copolymers increased in parallel with increases in the polymerization time. Structural, physiochemical, and thermal characterization of the obtained products was carried out using size-exclusion chromatography (SEC), proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) techniques. The polymerization kinetics of the star-shaped block copolymers were also investigated in detail.

Preparation and characterization of novel functional tri-block copolymer for constructing temperature/redox dual-stimuli responsive micelles

Herein, we reported a novel tri-block copolymer synthesized by segmented ring-opening polymerization of temperature-sensitive 5-(pyrrolidine-1-carbonyl) oxepan-2-one monomer (VPyCL) and redox-sensitive macrocyclic disulfide-substituted carbonate monomer (MSS). The structure of the copolymers was confirmed by GPC, 1H NMR and 13C NMR. The obtained tri-block copolymers could self-assemble in aqueous solution to form well-structured micelles, with the mPEG-b-PVPyCL block acting as the hydrophilic coronal and the PSS block acting as the hydrophobic core. Dynamic light scattering (DLS) studies confirmed that micelles formed by these tri-block copolymers with different block ratios could respond to different temperature ranges during the heating/cooling process and respond to reducing agent glutathione (GSH). In addition, transmission electron microscopy (TEM) results further confirmed the polymeric micelles’ dual-stimuli responsiveness. The potential application of this type of dual-stimuli responsive micelles in drug delivery systems was evaluated using doxorubicin (DOX) as the model molecule. The stimulus-dependent responsive behaviors of obtained micelles can be applied to the construction of smart materials capable of performing multiple functions under the appropriate conditions.

Preparation of cross-linking PVA copolymer modified by DAAM/ADH and application in paper surface sizing

Preparation of cross-linking PVA copolymer modified by DAAM/ADH and application in paper surface sizing

Preparation of Well-Controlled Isotactic Polypropylene-Based Block Copolymers with Superior Physical Performance via Efficient Coordinative Chain Transfer Polymerization

Preparation of Well-Controlled Isotactic Polypropylene-Based Block Copolymers with Superior Physical Performance via Efficient Coordinative Chain Transfer Polymerization

One‐For‐All Polyolefin Functionalization: Active Ester as Gateway to Combine Insertion Polymerization with ROP, NMP, and RAFT

This work develops the Polyolefin Active-Ester Exchange (PACE) process to afford well-defined polyolefin-polyvinyl block copolymers. α -Diimine Pd(II)-catalyzed olefin polymerizations were investigated through in-depth kinetic studies in comparison to an analog to establish the critical design that facilitates catalyst activation. Simple transformations lead to a diversity of functional groups forming polyolefin macroinitiators or macro-mediators for various subsequent controlled polymerization techniques. Preparation of block copolymers with different architectures, molecular weights, and compositions was demonstrated with ring-opening polymerization (ROP), nitroxide-mediated polymerization (NMP), and photoiniferter reversible addition-fragmentation chain transfer (PI-RAFT). The significant difference in the properties of polyolefin-polyacrylamide block copolymers was harnessed to carry out polymerization-induced self-assembly (PISA) and study the nanostructure behaviors.

One-For-All Polyolefin Functionalization: Active Ester as Gateway to Combine Insertion Polymerization with ROP, NMP, and RAFT.

This work develops the Polyolefin Active-Ester Exchange (PACE) process to afford well-defined polyolefin-polyvinyl block copolymers. α-Diimine PdII -catalyzed olefin polymerizations were investigated through in-depth kinetic studies in comparison to an analog to establish the critical design that facilitates catalyst activation. Simple transformations lead to a diversity of functional groups forming polyolefin macroinitiators or macro-mediators for various subsequent controlled polymerization techniques. Preparation of block copolymers with different architectures, molecular weights, and compositions was demonstrated with ring-opening polymerization (ROP), nitroxide-mediated polymerization (NMP), and photoiniferter reversible addition-fragmentation chain transfer (PI-RAFT). The significant difference in the properties of polyolefin-polyacrylamide block copolymers was harnessed to carry out polymerization-induced self-assembly (PISA) and study the nanostructure behaviors.

Hydrophobic core-hydrophilic shell graft block copolymers for unimolecular observation by AFM

Graft block copolymers for unimolecular observation by AFM are designed considering polymer morphology and affinity to substrate. For the observation on hydrophilic mica substrate, graft block copolymers with hydrophobic polystyrene (PS) core-hydrophilic poly(2-vinylpyridine) (P2VP) shell are successfully synthesized via anionic grafting polymerization from lithiated poly(p-methylstyrene) (PpMS). Preparation of the graft block copolymers are achieved by adding 2VP monomer to the chain end active PpMS-g-PS. As a confirmation of synthesis, AFM measurement clearly shows the molecules having a worm like structure lying on mica. According to cross-sectional analysis, the AFM image would be explained by aggregated PS core and extended P2VP shell. This reveals that controlling morphology of graft block copolymers on the substrate is achieved by designing side chains using segment affinities to the substrate.

On the Fundamental Polymer Chemistry of Inverse Vulcanization for Statistical and Segmented Copolymers from Elemental Sulfur.

In this concept review, the fundamental and polymerization chemistry of inverse vulcanization for the preparation of statistical and segmented sulfur copolymers, which have been actively developed and advanced in various applications over the past decade is discussed. This concept review delves into a discussion of step-growth polymerization constructs to describe the inverse vulcanization process and discuss prepolymer approaches for the synthesis of segmented sulfur polyurethanes. Furthermore, this concept review discusses the advantages of inverse vulcanization in conjunction with dynamic covalent polymerization and post-polymerization modifications to prepare segmented block copolymers with enhanced thermomechanical and flame retardant properties of these materials.

Construction of Enzyme-Responsive Micelles Based on Theranostic Zwitterionic Conjugated Bottlebrush Copolymers with Brush-on-Brush Architecture for Cell Imaging and Anticancer Drug Delivery.

Bottlebrush copolymers with different chemical structures and compositions as well as diverse architectures represent an important kind of material for various applications, such as biomedical devices. To our knowledge, zwitterionic conjugated bottlebrush copolymers integrating fluorescence imaging and tumor microenvironment-specific responsiveness for efficient intracellular drug release have been rarely reported, likely because of the lack of an efficient synthetic approach. For this purpose, in this study, we reported the successful preparation of well-defined theranostic zwitterionic bottlebrush copolymers with unique brush-on-brush architecture. Specifically, the bottlebrush copolymers were composed of a fluorescent backbone of polyfluorene derivate (PFONPN) possessing the fluorescence resonance energy transfer with doxorubicin (DOX), primary brushes of poly(2-hydroxyethyl methacrylate) (PHEMA), and secondary graft brushes of an enzyme-degradable polytyrosine (PTyr) block as well as a zwitterionic poly(oligo (ethylene glycol) monomethyl ether methacrylate-co-sulfobetaine methacrylate) (P(OEGMA-co-SBMA)) chain with super hydrophilicity and highly antifouling ability via elegant integration of Suzuki coupling, NCA ROP and ATRP techniques. Notably, the resulting bottlebrush copolymer, PFONPN9-g-(PHEMA15-g-(PTyr16-b-P(OEGMA6-co-SBMA6)2)) (P2) with a lower MW ratio of the hydrophobic side chains of PTyr and hydrophilic side chains of P(OEGMA-co-SBMA) could self-assemble into stabilized unimolecular micelles in an aqueous phase. The resulting unimolecular micelles showed a fluorescence quantum yield of 3.9% that is mainly affected by the pendant phenol groups of PTyr side chains and a drug-loading content (DLC) of approximately 15.4% and entrapment efficiency (EE) of 90.6% for DOX, higher than the other micelle analogs, because of the efficient supramolecular interactions of π–π stacking between the PTyr blocks and drug molecules, as well as the moderate hydrophilic chain length. The fluorescence of the PFONPN backbone enables fluorescence resonance energy transfer (FRET) with DOX and visualization of intracellular trafficking of the theranostic micelles. Most importantly, the drug-loaded micelles showed accelerated drug release in the presence of proteinase K because of the enzyme-triggered degradation of PTyr blocks and subsequent deshielding of P(OEGMA-co-SBMA) corona for micelle destruction. Taken together, we developed an efficient approach for the synthesis of enzyme-responsive theranostic zwitterionic conjugated bottlebrush copolymers with a brush-on-brush architecture, and the resulting theranostic micelles with high DLC and tumor microenvironment-specific responsiveness represent a novel nanoplatform for simultaneous cell image and drug delivery.

Thermoresponsive Glycopolypeptide Containing Block Copolymers, Particle Formation, and Lectin Interaction.

Amphiphilic block copolymers with a thermoresponsive poly(N-isopropylacrylamide) block and a glycopeptide block are synthesized and particle formation as well as interaction of the glyco-corona with lectins is investigated. The synthetic route comprises the preparation of block copolymers by N-carboxyanhydride polymerization and subsequent deprotection to obtain pH- and thermoresponsive poly(l-glutamic acid)-b-poly(N-isopropylacrylamide) (pGA-b-pNIPAM), which is then further modified with different amino sugars by a versatile coupling method with 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride (DMT-MM). The glycosylated pGA-b-pNIPAM block copolymers are investigated with regard to cloud point temperatures (Tcp ), particle size, and stability. The morphology of the particles is visualized using cryo-SEM. Zeta potential measurements are indicating that the saccharide moieties are located on the surface of the particles. This assumption is further substantiated by quantitative lectin interaction assays with nonaggregated and aggregated glycosylated pGA-b-pNIPAM. The interaction of the model lectin ConA with the block copolymers is independent of the degree of substitution in the nonaggregated state at room temperature. However, at 37°C, when particles of pGA-b-pNIPAM are present, the interaction becomes stronger with increasing degree of substitution. This interaction with lectins can be used for targeting saccharide-modified particles in drug delivery.

Preparation of functional copolymer based composite membranes containing graphene oxide showing improved electrochemical properties and fuel cell performance

The objective of this work is to prepare a functional copolymer of poly(acrylonitrile)-co-poly(2-Acrylamido-2-methyl-1-propanesulfonic acid) (PAN-co-PAMPS) and impregnation of graphene oxide (GO) into the copolymer followed by crosslinking to prepare conetwork composite membranes by simple and cost effective solution casting method and evaluating their structural, morphological, thermal, and mechanical properties. The successful incorporation of different amounts of GO content (0.1–1 wt%) within the polymer matrix was confirmed by FT-IR spectroscopy, X-ray diffraction, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The mechanical properties of the prepared crosslinked composite membranes are found to be greatly enhanced by the addition of GO in the copolymer matrix. The thermogravimetric analysis (TGA) demonstrated considerable improvements in thermal stability for the composite membrane with low GO content. The effect of loading of GO in the copolymer matrix on proton conductivity and fuel cell performance has been studied systematically. The membranes prepared by mixing with 0.5 wt% GO in the copolymer followed by crosslinking exhibited maximum ionic conductivity (Km), lower methanol permeability (PM), and higher relative selectivity. This observed PM value is much lower range from 3.02 × 10−7 to 11.9 × 10−7 cm2/s compared to the Nafion® 117 membrane (22 × 10−7 cm2/s). The fuel cell performance in terms of maximum power density and current density and the durability of the crosslinked composite membranes have also been evaluated here. Low PM, high Km, and high selectivity values show that functional co-polymer/GO crosslinked co-network composite membrane is a promising alternative membrane separator to replace the expensive Nafion® 117 for proton exchange membrane fuel cells (PEMFCs) application.

Synthesis of enzyme-responsive theranostic amphiphilic conjugated bottlebrush copolymers for enhanced anticancer drug delivery

Synthesis of polyfluorene (PF) based theranostic amphiphilic copolymers with simultaneously high drug loading efficiency and tumor microenvironment-specific responsiveness for promoted intracellular drug release and enhanced cancer therapy has been rarely reported likely due to the lack of efficient synthetic approaches to integrate these desirable properties. In this work, we recorded the successful preparation of well-defined theranostic amphiliphilic bottlebrush copolymers composing of fluorescent backbone of PF and tunable enzyme-degradable side chains of polytyrosine (PTyr) and POEGMA by integrating Suzuki coupling, NCA ROP and ATRP techniques. Notably, the resulting copolymer, PF25-g-(PTyr26-b-(POEGMA28)2 (P4) with two branched POEGMA brushes tethered to one PTyr termini for each unit could form steady unimolecular micelles with higher fluorescence quantum yield of 18.3% in aqueous and greater entrapment efficiency (EE) of 91.0% for DOX ascribed to the efficient π–π stacking interactions between PTyr blocks and drug molecules and the unique structure of branched hydrophilic brushes with a moderate chain length. DOX@P4 micelles revealed visualization of intracellular trafficking and accelerated drug release due to the enzyme-triggered degradation of PTyr blocks with proteinase K and subsequent deshielding of POEGMA corona for micelle destruction. In vitro and In vivo animal study further verified the intensive therapeutic efficiency with attenuated systematic toxicity. Taken together, we provided a universal strategy toward multifunctional polymeric delivery vehicles based on conjugated PF and biocompatible and degradable polypeptide by integratied Suzuki coupling and NCA ROP, and identified the branched structure of hydrophilic brushes for better performance of bottlebrush copolymers-based micelles for drug delivery applications. Statement of significanceSynthesis of polyfluorene (PF)-based theranostic amphiphilic copolymers with simultaneously high drug loading efficiency and tumor microenvironment-specific responsiveness for promoted intracellular drug release and enhanced cancer therapy has been rarely reported likely due to the lack of efficient synthetic approaches to integrate these desirable properties. We reported herein successful preparation of enzyme-responsive theranostic amphiliphilic bottlebrush copolymers with simultaneously high drug loading efficiency and tumor microenvironment-specific responsiveness for enhanced chemotherapy in vivo. This study therefore not only developed a universal strategy for the construction of multifunction polymeric vehicles based on the conjugated polymer of PF and degradable polypeptide by integrated Suzuki coupling and NCA ROP, but also emphasized the better stability of micelles endowed by the branched hydrophilic brushes than linear ones.

Preparation of Copolymer of 2-Methacryloyloxyethyldimethyl-3-sulfonic Acid Propylammonium Hydroxide and 3-(Methacryloyloxy) Propyltrimethoxysilane and Its Dye Adsorption Properties

While printing and dyeing bring us huge economic benefits, it also brings us huge challenges. Printing and dyeing will produce a large amount of wastewater, and the treatment of printing and dyeing wastewater has always been a concern. This work uses 2-methacryloxyethyl dimethyl-3-sulfonic acid propyl ammonium hydroxide, 3-(methacryloxy) propyl trimethoxysilane, and N, N’-methylene bispropylene as raw materials, and a photoinitiator is used to initiate polymerization under an ultraviolet lamp to prepare a copolymer gel. Taking the aqueous solution containing soap yellow as simulated dye wastewater, the adsorption performance of the prepared polymer for dyes was investigated. An ultraviolet spectrophotometer was used to investigate the effects of adsorption time, initial dye concentration, and polymer dosage on the adsorption performance. The performance test results show that the prepared polymer has high adsorption and removal efficiency for dyes containing soap yellow simulation, and has a potential application value.

Synthesis and thermal decomposition kinetics of tri-block copolymer ε-caprolactone / polybutadiene (PCL-PB-PCL); preparation of polyurethane network-based tri-block copolymer

Synthesis and thermal decomposition kinetics of tri-block copolymer ε-caprolactone / polybutadiene (PCL-PB-PCL); preparation of polyurethane network-based tri-block copolymer

Synthesis of colored siloxane somonomers for use in immunodiagnostics

The article presents approaches to the preparation of copolymers of polymethylmethacrylate using azo dyes, as well as data obtained as a result of a number of reactions to obtain methacryloxy-functionalized dyes and their copolymerization with methyl methacrylate. Synthesis of such polymer particles can be useful in the field of medicine — immunodiagnostics, latex agglutination reaction, flow cytometry, microspheric multiplex analysis.

Preparation of amphiphilic block copolymers by Reversible Addition Fragmentation Chain Transfer polymerization

Polystyrene macromolecular chain transfer agent (PS-CTA) was firstly synthesized by RAFT of styrene (St) in THF using benzyl dithiobenzoate (BDTB) as chain transfer agent and azobisisobutyronitrile (AIBN) as initiator. It was found that the molar ratio of monomers to chain transfer agents and reaction time had obvious effects on the molecular weight of PS-CTA, and the distribution of molecular weight (M w/M n ) decreases with the increase of the ratio of chain transfer agent to initiator by using gel permeation chromatography (GPC). The amphiphilic block copolymers polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) were synthesized using PS-CTA by RAFT. The structure, glass transition temperature (Tg) and molecular weight of the diblock copolymer were characterized by nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results showed that the structure of PS-b-P4VP was the target product. The segment ratio of PS-b-P4VP could be effectively controlled by changing the polymerization conditions in a large range.

L-menthol and thymol eutectic mixture as a bio-based solvent for the “one-pot” synthesis of well-defined amphiphilic block copolymers by ATRP

A bio-based eutectic mixture (EM), composed of L-menthol and thymol was used, for the first time, as solvent for the atom transfer radical polymerization (ATRP) of hydrophobic monomers (methyl acrylate (MA), methyl methacrylate (MMA), 2-(dimethylamino) ethyl methacrylate (DMAEMA), glycidyl methacrylate (GMA)) and hydrophilic monomers (2-hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) methyl ether acrylate (OEOA)). Well-defined homopolymers (1.02 <Ð < 1.47) were obtained using only 225 ppm of copper catalyst and a monomer/EM ratio (v/v) of 0.75. As a proof-of-concept, this new polymerization system allowed the preparation of well-defined amphiphilic block copolymers (ABs) of PMA-b-PHEA-Br, PMA-b-POEOA-Br and PDAMEMA-b-PHEA-Br by “one-pot” supplemental activator and reducing agent (SARA) ATRP, as well as a PMA-b-PHEA-b-PBA-Br triblock copolymer, after chain extension of a PMA-b-PHEA-Br diblock copolymer. The use of a unique solvent system opens a new route for the easy synthesis of ABs, with conditions that can be applied in large scale production.