Free Radical Copolymerization Process Research Articles

Rationally Designed Fluorinated Polycation Electrolytes for High-Rate, Dendrite-Free Lithium Metal Batteries.

The investigation of high-performance polymer-based electrolytes holds significant importance for advancing the development of next-generation lithium metal batteries (LMBs). In this work, a quasi-solid-state electrolyte (EFA-G) comprising pyrrolidinium type polymeric ionic liquids and fluoropolymers was synthesized through a photoinitiated free radical copolymerization process in the presence of solvate ionic liquids. EFA-G not only exhibited high ionic conductivity (9.87 × 10-4 S cm-1) but also had a wide electrochemical stability window (0-5.0 V vs Li+/Li). The improvement in Li+ transport number (tLi+ = 0.33) of EFA-G was attributed to the enhancement of the Li+ migration ability and the hindrance of anion mobility. Due to the shielding effect of the polymeric ionic liquid on the lithium electrode and the formation of a LiF-rich solid electrolyte interphase (SEI), EFA-G supported stable long-term plating/stripping cycling (>1000 h) of lithium symmetric cells. Li/LFP cells assembled with EFA-G at 30 °C exhibited excellent battery performance with a discharge specific capacity of 78.1 mA h g-1 at 8 C and long cycling life (>600 cycles) with high discharge specific capacity (127.8 mA h g-1 after 600 cycles). EFA-G also enabled decent performance for high-voltage cathode batteries. This work provides insights into the design of high-performance polymer-based electrolytes for LMBs.

Study on the polymerization process and monomer reactivity of EPEG‐type polycarboxylate superplasticizer

AbstractIn this study, the binary aqueous free radical copolymerization process of ethylene‐glycol monovinyl polyethylene glycol (EPEG) and acrylic acid (AA) was studied. The influence of monomer type and molar ratio on the conversion ratio of EPEG and the molar ratio of copolymer were investigated via gel permeation chromatography (GPC) by comparing the macromonomer molecular structures, side chain densities, and carboxyl group concentrations. According to the results, the reactivity of EPEG copolymerized with AA was higher than that of isoprenyl oxypoly (ethylene glycol) ether (IPEG, also referred to as TPEG) with AA. The copolymerization reaction between EPEG and AA could be completed within 30 min at 10–20°C. At the initial stage, the copolymer content quickly attained 60% within 15 min, reflecting the short induction period and high chain propagation rate constant. The fluidity tests in cement mortar revealed that polycarboxylate superplasticizers (PCEs) with short side chains and high conversion ratio exhibited better dispersion capacity than PCEs with long side chains.

DNA -based hydrogels for high-performance optical biosensing application

Analyte-sensitive DNA-based hydrogels find multiple applications in the field of biosensors due to their adaptable nature. Here, the design of DNA-based hydrogel and its application as sensing platform for the detection of a specific target sequence are presented. DNA-functionalized hydrogel structures were formed via a free radical co-polymerization process. A simple one-step probe immobilization procedure is reported: DNA probe molecules are added to the photoactive polymer mixture, dispensed onto a solid support, or a mold, and covalently attached while the hydrogel is formed through UV light exposure. Such hydrogels can be synthesized with desired recognition ability through the selection of a certain nucleotide sequence. Here we show the application of DNA-based hydrogel to detect the target with high performance in fluorescence microarray format and, additionally, to fabricate holographic surface relief gratings for label-free sensing assays.

Fabrication and synergistic antibacterial and antifouling effect of an organic/inorganic hybrid coating embedded with nanocomposite Ag@TA-SiO2 particles

The combination of antifouling and biocidal methods is an efficient antimicrobial strategy to alleviate environmental biofouling. Herein, a functional organic/inorganic hybrid coating with integrated terpolymer and hybrid Ag@TA-SiO2 nano spheres was designed and fabricated for antifouling purpose for the first time. The silicon-containing terpolymer (GHM) was fabricated via a simplified free radical co-polymerization process with glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (HEMA) and 3-(methacryloxypropyl) trimethoxysilane (MPS). It was expected that the (3-aminopropyl) triethoxysilane (KH550) would become immobilized at the epoxide ring of the GMA and eventually crosslinked, acting as a backbone for the final polymeric coating (PGHMK). Meanwhile, Ag nano-particles were decorated with tannic acid (TA) to have a composite surface structure and loaded with silica (SiO2) to form raspberries. The fabrication of the decorated and loaded antibacterial nano particle Ag@TA-SiO2 was environmental-friendly, high efficiency and low-cost. The PGHMK coating was expected to act as an effective antifouling barrier, and the embedded Ag@TA-SiO2 as a functional biocide carrier to collectively inhibit biofouling. To ensure the designed fabrication processes and the products, the microstructural, compositional, morphological changes of the copolymers and nanoparticles were characterized by means of FT-IR, 1H nuclear magnetic resonance, X-ray photoelectron spectroscopy and atomic force microscopy. The antifouling and bactericidal properties of the composite coatings were also systematically evaluated through measuring the adsorption of protein, growth of bacteria and attachment of microalgae on the coating surface. The results indicated that the coating suppressed 98.6 % of protein adsorption, and its antibacterial efficiency reached 99.1 % and 82.7 % for E. coli and S. aureus, respectively. The coating could also remarkably reduce the attachment of microalgae N. Closterium and Dicrateria zhanjiangensis by 93.5 % and 97.6 %, respectively. It is envisioned that the composite coating may provide a promising antifouling and antibacterial surface for marine engineering structures.

Degradation Urushiol Coating Composition Crosslinked by Diallyl Trisulfide

Urushiol (UR) was a kind of natural paint with a long history and excellent performance. Its high price restricts its development. For the sake of the sustainable development of UR, we prepared a new urushiol based coating composition which is of degradation. To be more specific, we develop a blend by diallyl trisulfide (TS) and urushiol, in which a free radical copolymerization process would take place to form a coating composition under UV irradiation. In this work, FT-IR was used to prove the reaction proces; the reversibly cross-linking properties and the rheological properties were also been proved; the basic mechanisms active in microstructure and the associated surface energy was elucidated; mechanical analysis and showed the mechanical property of coating composition. It was found that a copolymer formed by copolymerization of diallyl trisulfide and urushiol. The introduction of trisulfide bonds assists in achieving the reversibly cross-linking under extreme alkalinity (pH > 8). various trisulfide densities brought about different microstructures on the modified urushiol. The surface energy of coating composition had been enhanced after UV-curing and its increase was related to the phase inversion (represented by microstructure). What was more, the existence of flexible segments offered the coating composition with excellent flexibility (2 mm) and rheological properties (15 MPa.S), while the hardness of coating dropped to 2H.

Highly efficient cycloaddition of diluted and waste CO2 into cyclic carbonates catalyzed by porous ionic copolymers

It is believed that porous heterogeneous materials with excellent properties are promising candidates for efficient fixation of diluted and waste CO2. Herein, a family of mesoporous porous ionic copolymers (PIPs) was designed and prepared from the copolymerization of divinylbenzene (DVB) with vinyl-functionalized ionic liquids monomers through free radical copolymerization process. It was demonstrated that the heterogeneous PIP poly(divinylbenzene-1-allyl-tetramethylguanidinium bromide) PDVB-[AlTMG]Br-0.2 showed excellent activities in facile cycloaddition of CO2 into cyclic carbonates without using any external co-catalysts or metal additives. The results of characterizations and quantum mechanical calculations further showed that the specic hierarchical meso-macroporous structure of PDVB-[AlTMG]Br-0.2 offered the strongest binding interaction with SO and besides had a relatively good CO2 affinity, which results to the best cataltic activity for cycloaddition of CO2. Moreover, PDVB-[AlTMG]Br-0.2 exhibited high activities and good reusability in cycloaddition of 15 % diluted CO2 with various epoxides. It is believed that our work would have a great potential in energy-effective fixation of industrial combustion CO2 into high-value organic carbonates.

Biocompatible fluorescent nanoparticles for in vivo stem cell tracking

Efficient application of stem cells to the treatment of neurodegenerative diseases requires safe cell tracking to follow stem cell fate over time in the host environment after transplantation. In this work, for the first time, fluorescent and biocompatible methyl methacrylate (MMA)-based nanoparticles (fluoNPs) were synthesized through a free-radical co-polymerization process with a fluorescent macromonomer obtained by linking Rhodamine B and hydroxyethyl methacrylate. We demonstrate that the fluoNPs produced by polymerization of MMA–Rhodamine complexes (1) were efficient for the labeling and tracking of multipotent human amniotic fluid cells (hAFCs); (2) did not alter the main biological features of hAFCs (such as viability, cell growth and metabolic activity); (3) enabled us to determine the longitudinal bio-distribution of hAFCs in different brain areas after graft in the brain ventricles of healthy mice by a direct fluorescence-based technique. The reliability of our approach was furthermore confirmed by magnetic resonance imaging analyses, carried out by incubating hAFCs with both superparamagnetic iron oxide nanoparticles and fluoNPs. Our data suggest that these finely tunable and biocompatible fluoNPs can be exploited for the longitudinal tracking of stem cells.

Thermosetting Maleimide/Isobutene Alternating Copolymer as a New Class of Transparent Materials

AbstractWe synthesized an alternating copolymer of N‐allylmaleimide (AMI) and isobutene (IB) [poly(AMI‐alt‐IB)] as a new class of thermosetting polymers by the free radical copolymerization process. The reactivity of the maleimide group of the AMI monomer was evaluated to be 103 times higher than that of the N‐allyl group based on the results for the ternary copolymerization system composed of N‐methylmaleimide (MMI), N‐allylphthalimide (AP), and IB. The maleimide moiety exclusively participated in the propagation during the copolymerization of AMI with IB, resulting in the formation of the soluble poly(AMI‐alt‐IB). The copolymer included an alternating repeating structure consisting of maleimide and IB units in the main chain and the unreacted allyl group in the side chain. The onset temperature of the decomposition for poly(AMI‐alt‐IB) was over 400 °C in a nitrogen stream. The transparent cast film of poly(AMI‐alt‐IB) was readily cured upon heating without any catalyst.magnified image

Control of copolymer hydrodynamic volume distribution in a semibatch free radical copolymerization process

In copolymerization processes, molecular weight averages and copolymer composition are commonly used as property indices for reactor control purposes. In general, it is difficult to measure the molecular weight distribution of copolymer accurately by gel permeation chromatography (GPC) because there is no unique relationship between chain length and hydrodynamic volume for a copolymer with a heterogeneity in the composition distribution. In this paper, the hydrodynamic volume distribution is used as a primary control objective in a semibatch free radical copolymerization process. The hydrodynamic volume distribution of copolymer is modeled by computing the weight fraction of polymers over a number of hydrodynamic volume intervals. Then the target hydrodynamic volume distribution is obtained by designing optimal reactor operating policy. Both copolymer composition and the entire hydrodynamic volume distribution are controlled by adding reactants as a function of time. A numerical simulation example is presented for a styrene–methyl methacrylate copolymerization process to illustrate the proposed method.

Copolymer Hydrodynamic Volume Distribution in a Free Radical Copolymerization Process

Molecular weight averages and copolymer composition are commonly used as property indices for copolymers. In gel permeation chromatography (GPC), copolymer molecules are separated based on their hydrodynamic volumes in dilute solutions. For a copolymer with heterogeneity in the composition distribution, GPC chromatogram represents the hydrodynamic volume distribution which is not identical with its true molecular weight distribution that can be calculated from a copolymerization kinetic model. In this paper, a new method is presented for modeling the hydrodynamic volume distribution of a copolymer in a batch free radical copolymerization process. The hydrodynamic volume distribution is calculated by computing the weight fraction of polymers over a number of hydrodynamic volume intervals. Chain length and copolymer composition are related to hydrodynamic volume using the bivariate distribution function and the universal calibration method with composition dependent Mark-Houwink constants.