Conventional Free Radical Polymerization Research Articles

An Innovative Approach for Tailoring Molecularly Imprinted Polymers for Biosensors-Application to Cancer Antigen 15-3.

This work presents a novel approach for tailoring molecularly imprinted polymers (MIPs) with a preliminary stage of atom transfer radical polymerization (ATRP), for a more precise definition of the imprinted cavity. A well-defined copolymer of acrylamide and N,N'-methylenebisacrylamide (PAAm-co-PMBAm) was synthesized by ATRP and applied to gold electrodes with the template, followed by a crosslinking reaction. The template was removed from the polymer matrix by enzymatic/chemical action. The surface modifications were monitored via electrochemical impedance spectroscopy (EIS), having the MIP polymer as a non-conducting film designed with affinity sites for CA15-3. The resulting biosensor exhibited a linear response to CA15-3 log concentrations from 0.001 to 100 U/mL in PBS or in diluted fetal bovine serum (1000×) in PBS. Compared to the polyacrylamide (PAAm) MIP from conventional free-radical polymerization, the ATRP-based MIP extended the biosensor's dynamic linear range 10-fold, improving low concentration detection, and enhanced the signal reproducibility across units. The biosensor demonstrated good sensitivity and selectivity. Overall, the work described confirmed that the process of radical polymerization to build an MIP material influences the detection capacity for the target substance and the reproducibility among different biosensor units. Extending this approach to other cancer biomarkers, the methodology presented could open doors to a new generation of MIP-based biosensors for point-of-care disease diagnosis.

Designing magnetic catalysts based on gold nanoparticles supported by ethylenediamine tetraacetic acid functionalized amino‐modified poly(N‐isopropyl acrylamide) for reduction of nitro compounds in water

AbstractA novel smart catalyst was developed with amino‐modified thermo‐responsive poly(N‐isopropyl acrylamide) (PNIPAM) grafts on silica‐coated magnetic nanoparticles using the conventional free radical polymerization process. By this methodology, the polymer was successfully grafted mainly onto silica‐modified iron oxide nanoparticles (Fe3O4@Si). The PNIPAM‐grafted Fe3O4@Si was then subjected to ethylenediamine treatment to produce the amino‐functionalized support (Fe3O4@Si@PNIPAM‐NH2), which was subsequently modified with carboxyl functional groups by using EDTA (ethylenediaminetetraacetic acid) to create Fe3O4@Si@PNIPAM‐NH2‐EDTA. Au nanoparticles were then decorated on this support through its two amines and four carboxylates. Different methods were used to study this novel catalyst, including inductively coupled plasma, Fourier transport infrared spectroscopy, TGA, dynamic light scattering, SEM, energy‐dispersive X‐ray analysis, vibrating sample magnetometry, XRD and elemental CHN analysis. The reduction of several aryl‐nitro derivatives demonstrated a significant catalytic activity for the as‐synthesized gold catalyst (Fe3O4@Si@PNIPAM‐NH2‐EDTA‐Au). The Au catalyst can be successfully removed from the reaction components using a magnetic field and used again in eight successive reduction reactions without significant gold leaching and loss of catalytic activity. © 2024 Society of Industrial Chemistry.

Polyvinylchloride surface modified with polymer brushes for reduced protein, cell and bacteria attachment

AbstractThe objective of this study was to coat negatively charged polymer brushes by a covalent bond onto the surface of polyvinylchloride using a simple conventional surface free radical polymerisation technique. The coated surfaces were assessed with contact angle, protein adsorption, cell adhesion, and bacterial adhesion. Bovine serum albumin and bovine fibrinogen were used for protein adsorption evaluation. Mouse fibroblast (NIH‐3T3) cells and Pseudomonas aeruginosa were used to assess surface adhesion. Results show that the surface modified with all the attached polymers exhibited significantly reduced contact angle, protein adsorption, and cell as well as bacterial adhesion among which the negatively charged polymers showed extremely low values in all the tests. The negatively charged polymer shows its contact angle at 5° as compared to 70° for original polyvinylchloride. Its bovine serum albumin, bovine fibrinogen, 3T3 adhesion, and P. aeruginosa adhesion were 93%, 84%, 92%, and 92% lower than the original PVC, respectively. Furthermore, the polyvinylchloride surface coated with negatively charged polymer brushes exhibited a hydrogel‐like property. The results indicate that coating a polyvinylchloride surface with acrylic acids using a simple surface‐initiated free radical polymerisation and then converting those to negatively charged salts can be an effective and efficient route for fouling‐resistant applications.

Unique Polymer-Stabilized Liquid Crystal Structure Prepared by Addition of a Reversible Addition-Fragmentation Chain Transfer Agent.

Polymer-stabilized liquid crystals (PSLCs) are important electrically switchable materials due to their superior electro-optical properties. Nevertheless, it remains a formidable challenge to balance PSLCs' instant electro-optical performance and long-term durability due to their relatively low polymer content and the related sensitivity to external force. Herein, we demonstrate the possibility of regulating the polymer network structure in PSLCs via reversible addition-fragmentation chain transfer (RAFT) polymerization reactions of acrylate monomers with a chain transfer agent (CTA). By controlling the concentration of CTA and conditions of photopolymerization, the kinetics of the polymerization reaction can be modified. Compared to conventional free-radical (FR) polymerization, the reduced chain growth rate leads to sufficient chain relaxation, reorientation of liquid crystal (LC) directors, and alleviation of shrinkage stresses in the RAFT polymerization process. This in turn produces an ordered polymer network structure in the vertical direction and a uniform distribution in the horizontal plane. As a result, the PSLC network presents increased elasticity with a lower hysteresis effect and greatly improved durability. Our research offers insightful guidance for the fine-tuning of polymer network structures to prepare advanced LC/polymer composite structures with outstanding performances.

Porous Poly(2-hydroxyethyl methacrylate) Hydrogel Scaffolds for Tissue Engineering: Influence of Crosslinking Systems and Silk Sericin Concentration on Scaffold Properties.

Tailored porous structures of poly(2-hydroxyethyl methacrylate) (PHEMA) and silk sericin (SS) were used to create porous hydrogel scaffolds using two distinct crosslinking systems. These structures were designed to closely mimic the porous nature of the native extracellular matrix. Conventional free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) was performed in the presence of different concentrations of SS (1.25, 2.50, 5.00% w/v) with two crosslinking systems. A chemical crosslinking system with N'N-methylene bisacrylamide (MBAAm) and a physical crosslinking system with dimethylurea (DMU) were used: C-PHEMA/SS (crosslinked using MBAAm) and C-PHEMA/pC-SS (crosslinked using MBAAm and DMU). The focus of this study was on investigating the impact of these crosslinking methods on various properties of the scaffolds, including pore size, pore characteristics, polymerization time, morphology, molecular interaction, in vitro degradation, thermal properties, and in vitro cytotoxicity. The various crosslinked networks were found to appreciably influence the properties of the scaffolds, especially the pore sizes, in which smaller sizes and higher numbers of pores with high regularity were seen in C-PHEMA/1.25 pC-SS (17 ± 2 μm) than in C-PHEMA/1.25 SS (34 ± 3 μm). Semi-interpenetrating networks were created by crosslinking PHEMA-MBAAm-PHEMA while incorporating free protein molecules of SS within the networks. The additional crosslinking step involving DMU occurred through hydrogen bonding of the -C=O and -N-H groups with the SS, resulting in the simultaneous incorporation of DMU and SS within the PHEMA networks. As a consequence of this process, the scaffold C-PHEMA/pC-SS exhibited smaller pore sizes compared to scaffolds without DMU crosslinking. Moreover, the incorporation of higher loadings of SS led to even smaller pore sizes. Additionally, the gelation time of C-PHEMA/pC-SS was delayed due to the presence of DMU in the crosslinking system. Both porous hydrogel scaffolds, C-PHEMA/pC-SS and PHEMA, were found to be non-cytotoxic to the normal human skin dermal fibroblast cell line (NHDF cells). This promising result indicates that these hydrogel scaffolds have potential for use in tissue engineering applications.

Au nanoparticles decorated on EDTA functionalized Poly (NIPAM-co-allylamine) grafted Fe3O4 for reduction of nitroarenes

A novel smart catalyst of Au nanoparticles supported on EDTA (ethylenediaminetetraacetic acid) functionalized temperature-sensitive copolymer consists of N-isopropyl acrylamide (NIPAM) and allylamine onto silica-modified Fe3O4 MNP (Fe3O4@Si@P(NIPAM-co-allylamine)-EDTA@Au) was prepared. Initially, Fe3O4 was synthesized and modified with silica particles, and then P(NIPAM-co-allylamine) was grafted onto it via conventional free radical polymerization. Afterwards, polymer grafted MNPs were functionalized with EDTA and decorated with Au NPs to produce an organized heterogenous catalytic structure. Easy separation and recycling, high dispersion of catalytic sites, as well as good thermal stability, and superior efficiency in water as a green solvent are among the great advantages of this system. The novel heterogeneous catalyst showed remarkable catalytic activity for the reduction of numerous aryl-nitro derivatives containing electron-poor, electron-rich, and ortho-substituted. This catalytic system performed excellently for at least 8 repeated cycles without significant degradation in catalytic activity, structure change, and leaching. Furthermore, the temperature responsiveness feature of the catalyst causes the catalyst's switchable on/off behavior.

Random and block architectures of N-arylitaconimide monomers with methyl methacrylate

Abstract “Itaconimide” is the members of imide (–CO–NH–CO–) family with reactive exocyclic double bond and it is easily obtained from the renewable resource i.e. D-glucose. The polymerization of various N-arylitaconimide (NAI) monomers with methyl methacrylate (MMA) have been reported to improve the glass transition temperature (T g) and thermal stability of poly(methyl methacrylate) (PMMA). In literature, these studies have been done mostly using conventional free radical polymerization methods, which restricts the architecture of copolymers to “random” only. The block copolymers of NAI and MMA are an important due to the combination of glassy PMMA and thermally stable poly(NAI), which offers its applications for higher temperature service. The architectural control of polymers in provisions of its topology, composition, and various functionalities is possibly obtained using reversible-deactivation radical polymerizations (RDRPs). In RDRPs, the concentration of free radical is controlled in such a way that the termination reactions are minimized (normally in range of 1–10 mol%), and not allowed to obstruct with the desired architecture. However, this is possible by achieving (or by establishing) a rapid dynamic equilibrium between propagating radical and dormant species (i.e. R–X). Among all RDRPs, the atom transfer radical polymerization (ATRP) is very popular and adaptable method for the synthesis of polymers with specifically controlled architecture. Two different architectures of NAI and MMA copolymers are reported using ATRP process. The effect of various pedant groups on the rate constants of propagation (k p) and thermal properties NAI and MMA copolymers is studied. The poly(NAI-ran-MMA)-b-poly(MMA) are stable up to 200 °C and degraded in three steps. Whereas, the poly(NAI-ran-MMA)-b-poly(NAI) are stable up to 330 °C and degraded in two steps. The density functional theory methods are used for calculation of equilibrium constants (K ATRP) for the ATRP process for the series of laboratory synthesized alkyl halides. A good agreement was observed between the experimentally determined and theoretically calculated K ATRP values. The mechanistic studies are carried for poly(NAI-ran-MMA) copolymer system using statistical model discrimination method along with 1H decoupled 13C NMR spectroscopy. For studying the mechanism of copolymerization of NAI and MMA via ATRP methods, “trimer model or penultimate model” will be more accurate than “dimer model or terminal model”.

Kinetic and Equilibrium Function and Switchable Catalytic Activity of Some Thermo-Responsive Hydrogel Metal Absorbents Based on Modified PNIPAM

Synthesis and identification of some thermo-responsive hydrogel metal absorbents based on Schiff base modified PNIPAM is described. PNIPAM hydrogel is produced through conventional free-radical polymerization method. The hydrogel is amino modified with different amines and then treated with various aldehydes to make polymeric Schiff-bases supposing to utilize as an absorbent for Cu salt. Characterization of the as-prepared hydrogels was performed properly and confirmed the corresponding structures. Kinetic and equilibrium function of the absorbents and the effect of distinct variables like pH, adsorbent amount and contact time in the absorption process are investigated in detail. Kinetic and adsorption isotherm data agreed with pseudo-second order model and Langmuir isotherm, respectively. The maximum value of adsorption capacity of the prepared adsorbent was around 8550 mg g−1. In addition, the corresponding switchable catalytic activity using one of the thermo-responsive hydrogel metal absorbents in the reduction of 4-nitro phenol to 4-amino phenol in the role of model reaction is examined.

Effect of Radical Polymerization Method on Pharmaceutical Properties of Π Electron-Stabilized HPMA-Based Polymeric Micelles.

Polymeric micelles are among the most extensively used drug delivery systems. Key properties of micelles, such as size, size distribution, drug loading, and drug release kinetics, are crucial for proper therapeutic performance. Whether polymers from more controlled polymerization methods produce micelles with more favorable properties remains elusive. To address this question, we synthesized methoxy poly(ethylene glycol)-b-(N-(2-benzoyloxypropyl)methacrylamide) (mPEG-b-p(HPMAm-Bz)) block copolymers of three different comparable molecular weights (∼9, 13, and 20 kDa), via both conventional free radical (FR) and reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were subsequently employed to prepare empty and paclitaxel-loaded micelles. While FR polymers had relatively high dispersities (Đ ∼ 1.5-1.7) compared to their RAFT counterparts (Đ ∼ 1.1-1.3), they formed micelles with similar pharmaceutical properties (e.g., size, size distribution, critical micelle concentration, cytotoxicity, and drug loading and retention). Our findings suggest that pharmaceutical properties of mPEG-b-p(HPMAm-Bz) micelles do not depend on the synthesis route of their constituent polymers.

Reprocessable, creep-resistant covalent adaptable networks synthesized using conventional free-radical polymerization conditions with piperidine-based and non-piperidine-based dynamic dialkylamino disulfide chemistry

Reprocessable and creep-resistant poly(n-hexyl methacrylate) dynamic networks were synthesized from piperidine-based and non-piperidine-based dialkylamino disulfide cross-linkers at conventional polymerization conditions.

Shape Control over the Polymer Molecular Weight Distribution and Influence on Rheological Properties

The shape, breadth, and average molecular weight of the overall molecular weight distribution (MWD) largely define polymer properties. In conventional free-radical polymerization, control over this distribution is through the many competing kinetic pathways dominated by radical termination events. “Living” radical polymerization mechanistically minimizes these termination events, providing a facile route to a desired Gaussian distribution with the distribution breadth dependent upon the activity of the catalyst or modulating agent. However, producing unusually shaped distributions can only be achieved through modeling of the complex polymerization kinetics and invoking feeding and other methods. Here, we construct square, slanted, and chair-like MWDs by blending two to four polymers made using a low-reactive RAFT agent with dispersities close to 2. The synthesis of these polymers, unlike that of polymers made with high-reactive RAFT agents, is simple, scalable, and importantly reproducible as the MWD is independent of conversion, making this polymerization method virtually and kinetically model-free. The blending method described here overcomes many of the difficulties in producing unusually shaped MWDs and allows control over the shape and breadth of the MWD. The concept further provides a general synthetic strategy for studying important structure–property relationships of polymers with desired processing and performance characteristics. This is demonstrated by measurement and modeling analysis of the linear viscoelastic properties of selected samples, which provides a way to tailor the properties of polymers by controlling the form of their MWD via blending. Unlike conventional approaches analyzing the effects of the MWD, its actual shape is considered and its effect on the properties is addressed.

Development of Myrcene‐Based Resins with Amine Ended Poly(Propylene Glycol) Side Chains Bonded Through Hydroxyurethane Linkages

AbstractHybrid non‐isocyanate poly(urethanes) (HNIPUs) are designed from a precursor whose carbonate functionality is derived from epoxy‐functional statistical copolymers. Specifically, a bio‐based diene (β‐myrcene) is copolymerized via conventional free radical polymerization with glycidyl methacrylate (GMA) at different molar ratios, producing flexible copolymers with epoxy pendant groups, which are then reacted with carbon dioxide to yield the precursors with cyclic carbonate functionality. Subsequent addition of an amine‐terminated telechelic poly(propylene glycol) (PPG) forms urethane linkages in the side chains, whose concentration is tuned by varying the GMA initial molar fraction. The NIPUs are end‐capped with silanes to enable moisture curing, resulting in HNIPUs with elongations at break up to 150%, and relatively low elastic moduli varying from 32 kPa to 50 kPa as the number of urethane side linkages increases from 6 to 22. The swelling ratio of the NIPUs is also measured in tetrahydrofuran (THF). As the number of urethane side chains increases, the swelling ratio of the NIPUs decreases (710% to 620%), indicating a higher crosslinking density. All samples have gel contents higher than 50% in THF, indicating non‐crosslinked species in the hybrid samples which confirms the relatively low reported tensile moduli.

Crosslinked polymethacrylate absorbent with phenylalanine and stearate pendants

Herein, we report a new class of oil absorbents via conventional free radical polymerization method to prepare polymethacrylate gels with a range of crosslinking density having both phenylalanine and stearate moieties in the gel matrix. Analogue crosslinked gel was also synthesized with only stearate pendants without phenylalanine. Solvent absorbing capacity of gels was studied in various solvents with different dielectric constants. The mechanical property and morphology of the absorbents were studied by rheological method and field emission scanning electron microscopy, respectively. Modulation of porosity, absorption capacity and mechanical property of the absorbent were achieved with the variation of crosslinking density. The side chain pendants in the absorbent played an important role toward the solvent uptake capabilities. The absorbent readily can uptake 66 times chloroform and 14 times petrol of its dry weight at room temperature. Overall, the solvent uptake capacity of a new class of absorbents was well studied in this report.

Degradable Polystyrene via the Cleavable Comonomer Approach

Polystyrene (PS) is a major commodity polymer widely used in various applications ranging from packaging to insulation thanks to its low cost, high stiffness, and transparency as well as its relatively high softening temperature. Similarly to all polymers prepared by radical polymerization, PS is constituted of a C–C backbone and thus is not degradable. To confer degradability to such materials, the copolymerization of vinyl monomers with a cyclic monomer that could undergo radical ring-opening is an efficient method to introduce purposely cleavable bonds into the polymer backbone. Dibenzo[c,e]-oxepane-5-thione (DOT) is a cyclic thionolactone monomer known for its efficient copolymerization with acrylate derivatives but so far could not be incorporated into PS backbones. From a theoretical study combining density functional theory (DFT) and kinetic models using the PREDICI software, we showed that the modification of experimental conditions could overcome these limitations and that high molar mass degradable polystyrene (Mw close to 150 000 g·mol–1) could be prepared via statistical insertion of thioester groups into the polymer backbone. This copolymerization process is compatible with conventional free radical polymerization and reversible deactivation radical polymerization (RDRP) techniques such as nitroxide mediated polymerization (NMP). Thanks to favorable reactivity ratios allowing only a few mol % of thioester units to be randomly incorporated, there was no major modification of the thermal and mechanical properties of the PS. The degradation of such PS could be performed in tetrahydrofuran (THF) at room temperature (RT) in 1 h using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a base, leading to oligomers with Mn close to 2000 g·mol–1. We successfully demonstrate further applicability of these copolymerization systems for the phototriggered decomposition of PS in solution as well as the synthesis of cross-linked PS networks degradable into soluble side products.

Development of Synthesis and Application of High Molecular Weight Poly(Methyl Methacrylate).

Poly(methyl methacrylate) (PMMA) is widely used in aviation, architecture, medical treatment, optical instruments and other fields because of its good transparency, chemical stability and electrical insulation. However, the application of PMMA largely depends on its physical properties. Mechanical properties such as tensile strength, fracture surface energy, shear modulus and Young’s modulus are increased with the increase in molecular weight. Consequently, it is of great significance to synthesize high molecular weight PMMA. In this article, we review the application of conventional free radical polymerization, atom transfer radical polymerization (ATRP) and coordination polymerization for preparing high molecular weight PMMA. The mechanisms of these polymerizations are discussed. In addition, applications of PMMA are also summarized.

Synthesis and property of EPEG‐based polycarboxylate ether superplasticizers via RAFT polymerization

AbstractPolycarboxylate ether superplasticizers (PCEs) with comb‐shaped molecular structures have attracted considerable attention in the area of admixtures for construction engineering. However, there are some contradictions in studying the relationship between the molecular structure and property of PCE due to its random structure based on traditional free radical polymerization, which is confused for designing and developing novel PCEs. In this article, a series of reversible addition fragmentation chain transfer (RAFT) polymerization‐based polycarboxylate ether superplasticizers (RPCs) were prepared by the copolymerization of acrylic acid (AA) and ethylene‐glycol monovinyl polyethylene glycol (EPEG). The chemical structure and composition of RPCs were characterized and their adsorption behavior and dispersion properties were conducted. The results demonstrate that the molecular weights of RPCs do not vary significantly with prolonging reaction time, and the actual monomer ratio in RPCs displays a significant change to the feed one due to the monomer reactivity and conversion at higher reaction temperature, which is different from conventional free radical polymerization. The dispersion and adsorption properties of RPCs to cement were evaluated by slurry fluidity tests and total organic carbon (TOC) experiments. The effect of polymerization temperature and time on the dispersion ability has been systematically studied. The results indicate that the dispersion ability and adsorption capacity of RPCs are closely related to their molecular structures. The dispersion ability of RPCs were enhanced with increasing carboxyl group density in a certain range of monomer molar ratios (≤6:1). This study will provide a new platform for designing and developing high‐performance and rational cost‐effective superplasticizers with well‐defined structure and controlled molecular weight.

Poly(poly(ethylene glycol) methyl ether methacrylate-co-acrylonitrile) gel polymer electrolytes for high performance lithium ion batteries: Comparing controlled and conventional radical polymerization

In this work, a series of crosslinked poly(poly(ethylene glycol) methyl ether methacrylate-co-acrylonitrile) [P(PEGMA-co-ACN)] copolymers has been designed as gel polymer electrolytes (GPEs) for high-safety and high voltage lithium ion batteries. Two approaches including conventional free radical polymerization (FRP) and control radical polymerization (CRP) through one-step reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) were used to synthesize GPEs with different molar ratios of ACN and PEGMA. Although there was not observed remarkable advantage of polymerization method in different monomer compositions, P(PEGMA-co-ACN) by 50 mol.% ACN and PEGMA prepared via FRP exhibited the maximum ionic conductivity of 5.1 * 10−3 S cm−1, transference number (t+) of 0.55, and exceptional swelling ratio value of 150% in 30 min. Interestingly, it affords a supreme electrochemical stability window up to 5.13 V vs. Li/Li+, the charge capacity of 205 mAh g−1 at 0.1 C, and capacity retention of 89% after 100 cycles.

The enhanced adsorption properties of molecular imprinted polymer material prepared using nitroxide-mediated Radical Deactivation Reversible Polymerization

The origin of the improved performance of Molecular Imprinted Polymers (MIPs) prepared by Nitroxide-Mediated Radical Deactivation Reversible Polymerization (NMRP) and by conventional Free Radical Polymerization (FRP) was investigated through a detailed interpretation of adsorption onto imprinted- and non-imprinted materials. MIPs designed for the adsorption of 3,5-dichlorohydroxyacetophenone (DCHA) were copolymers of methacrylic acid and styrene cross-linked by ethylene glycol dimethacrylate. Modelling the adsorption isotherms using the Langmuir–Volmer model showed that the enhanced adsorption to NMRP MIP was due to a higher density of molecular imprints rather than a higher affinity of the molecular imprints for DCHA. Adsorption was exothermic onto molecular imprints and athermal off them; adsorption caused an increase of entropy. The interactions between monomer and DCHA measured in solution and the influence of pH on adsorption pointed out hydrogen bonding between the MIP carboxylic acids and the DCHA phenol group as the main contribution to adsorption. • Higher adsorption to Molecularly Imprinted material from Radical Deactivation Reversible than Free Radical Polymerization. • Enhanced adsorption comes from a higher density of molecular imprints. • Affinity to molecular imprints was identical for Radical Deactivation Reversible and Free Radical Polymerizations.

Poly(poly[ethylene glycol] methyl ether methacrylate)/graphene oxide nanocomposite gel polymer electrolytes prepared by controlled and conventional radical polymerizations for lithium ion batteries

Nanocomposite gel polymer electrolyte (GPE) films based on poly(poly[ethylene glycol] methyl ether methacrylate)/graphene oxide (GO) (P[PEGMA-GO]) have been prepared by in situ conventional free radical polymerization (FRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization as controlled radical polymerization (CRP) using 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) as RAFT agent. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that prepared nanocomposite films had amorphous structure and also, thermogravimetric analysis (TGA) showed appropriate thermal stability of samples. GPEs prepared via FRP showed slight higher ionic conductivity that GPEs prepared via RAFT polymerization. In both synthetic approaches, an optimum GO amount of 0.3 wt. % was obtained considering ionic conductivity. At ambient temperature, P(PEGMA-GO) with 0.3 wt. % GO prepared via FRP indicated the highest ionic conductivity of 4.05 × 10−3 S cm−1, a satisfactory lithium ion transference number (t+) of 0.6, and the excellent interface compatibility with electrodes. The lithium ion battery with P(PEGMA-GO0.3%) as GPE also exhibited electrochemical stability window up to 4.6 V vs. Li/Li+, a high charge-discharge capacity of 179 mAh g−1 at 0.1 C, and capacity retention of 91% after 100 cycles.

Preparation of well-defined Poly(Vinyl alcohol) by hydrolysis of Poly(Vinyl acetate) synthesized by RAFT suspension polymerization

Poly(vinyl alcohol) (PVA) is a widely used synthetic polymer that is made by hydrolysis of poly(vinyl acetate) (PVAc). A significant challenge in the production of well-defined PVA arises due to the high frequency of chain transfer reactions that occur in the radical polymerization of PVAc, which limits the molecular weight and leads to branching. Upon hydrolysis of PVAc, both acetate groups and branch points can be hydrolyzed, resulting in a PVA with a significantly lower molecular weight than the parent PVAc, making control over the molecular weight distribution of PVA difficult. In this work we demonstrate the production of PVAc with a well-defined and linear structure by reversible addition-fragmentation chain transfer (RAFT) polymerization under conditions in which chain transfer is reduced. PVAc samples were prepared by suspension polymerization using both conventional free-radical polymerization and RAFT polymerization at 50 °C. When using RAFT polymerization, upon hydrolysis there was a minimal decrease of the degree of polymerization and high molecular weight PVA of low dispersity was obtained. These results demonstrate the synthesis of well-defined PVA and offers a potential route to the production of PVAc and PVA products with uniform properties.