Monomer Reactivity Research Articles

Neodymium‐Mediated Coordinative Chain Transfer Homopolymerization of Bio‐Based Myrcene and Copolymerization With Butadiene and Isoprene

ABSTRACTCoordinative chain transfer polymerization (CCTP) has emerged as a powerful strategy in controlling the polymerization behavior of petroleum‐based diene monomers of butadiene (BD) and isoprene (Ip) and has been extensively studied in the past few years. Nevertheless, for the bio‐based terpene monomer of myrcene (My), its polymerization performance is rarely disclosed. Herein, by using a neodymium‐based Ziegler–Natta catalytic system of Nd(vers)3/Al(i‐Bu)2H/AlEt3/EASC, the CCTP of My was systematically evaluated. In order to concrete the CCTP characteristic, more evidence was provided, including its comprehensive comparison with the Ip system, kinetic studies, and seeding polymerization. All these results have led to the conclusion that, despite the long alkenyl substitute in the My monomer, CCTP properties were still demonstrated, albeit with relative lower chain transfer efficiency. Coordinative chain transfer copolymerization (CCTcoP) of My with BD or Ip was also studied, in which, similar to My homopolymerization, well‐controlled polymerization behaviors were also revealed that gave narrow polydispersities, high atom economies, as well as controlled copolymer compositions. Monomer reactivity ratio studies by Fineman‐Ross plot revealed that, for CCTcoP of My and BD, rMy and rBD were determined as 0.62 and 0.27, whereas for My/Ip system, rMy and rIp values were 0.74 and 0.24, respectively, implying both two systems preferred to undergo cross‐polymerization to give copolymers rather than homopolymer sequences.

Disparity between rate and selectivity in the controlled synthesis of gradient conjugated copolymers

In this report, a one-pot synthesis of gradient copolymers is attempted employing Kumada catalyst transfer condensative polymerization (KCTCP). The hypothesis that a more reactive monomer is preferentially being built into the chain at the beginning, while the slower reacting monomer is only being built into the chain at the end due to it being in excess, is investigated. The monomer rate constants are influenced by the usage of differently sized sidechains (octyl versus 3-octyldodecyl) and nucleophilicity of the monomers (thiophene versus selenophene). Nonetheless, while the rate constants differ by a factor 2, no selectivity is obtained. The cause thereof is further investigated by increasing the sterical crowdedness around the catalyst-complex by employing a 4-substituted monomer, the polymerization of which also gave rise to random copolymers. Accompanied by density functional theory calculations of the geometry and Gibbs free energy, it is concluded that the distance between the nickel catalyst and the polymer chain is much smaller compared to the distance between the catalyst and the incoming monomer. This results in different polymerization rates (depending on the polymer-nickel complex), while having no selectivity for one incoming monomer over the other.

Preparation of Nitrogen‐Phosphorus‐Silicon Synergistic Intumescent Flame Retardant and Its Effect on the Flame Retardancy of Waterborne Polyurethane

ABSTRACTWaterborne polyurethane is widely used across various industries, including construction, automotive, leather, and thermal insulation, due to its exceptional properties such as lightweight, thermal insulation, and corrosion resistance. However, its susceptibility to combustion significantly limits its utility, highlighting the critical need for integrating flame retardants into polyurethane formulations. This study focuses on the synthesis of a novel hyperbranched flame retardant, HBNPSi, achieved by manipulating the proportions of 10‐(2′,5′‐dihydroxyphenyl)‐9,10‐dihydro‐9‐oxa‐10‐phospha‐phenanthrene‐10‐oxide (DOPO‐BQ), 1,3,5‐trihydroxyethylcazinone (THC), and isocyanatopropyltrihydroxyethylsilane (IPTS) as the constituent materials. The structural characteristics of the flame retardant were analyzed using infrared spectroscopy, carbon residue analysis, swelling height measurements, and x‐ray spectroscopy (EDS). HBNPSi was then incorporated as a reactive monomer in the pre‐polymerization reaction of aqueous polyurethane to produce a hyperbranched flame‐retardant polyurethane. The flame‐retardant properties were assessed through various tests, including oxygen index, vertical and horizontal combustion, thermo‐red in‐line, and cone calorimetry. Notably, the introduction of DOPO as a flame retardant in a ratio of BQ:THC = 2:1 resulted in an oxygen index of 29% and achieved a V‐0 flame‐retardant rating. Additionally, the decomposition temperature increased from 250°C to 300°C, while the heat release rate (HRR) decreased by 47.8%, total heat release (THR) decreased by 28.2%, and total smoke production (TSP) was reduced by 46.2%.

The Inhibitory Effect of Low Phosphorus and Low Molecular Weight Terpolymer Scale Inhibitor on Calcium Scale in Oilfields

ABSTRACTThe study utilized itaconic acid (IA), N‐hydroxyethyl acrylamide (HEAA), and sodium hypophosphite (SHP) as starting materials for a free radical polymerization process. This process resulted in creating a new type of low‐phosphorus terpolymer scale inhibitor called P(IA‐HEAA‐SHP). Its primary application was as an effective scale inhibitor to block CaCO3 and CaSO4. FTIR, 1H‐NMR, and 13C‐NMR were used to characterize the synthesized copolymer structures, and it was confirmed that the synthesized products had the desired structures. The synthesis conditions have been optimized using the static scale inhibition approach, which involved adjusting the monomer ratio, initiator dosage, and reaction time. This resulted in the synthesis of polymeric scale inhibitors with outstanding scale inhibition properties. Additionally, GPC was employed to examine the correlation of the molecular weight of the polymers with their scale inhibition properties at various reaction times. The results showed that when the monomer ratio n(IA):n(HEAA) = 1.5:1, the SHP dosage mass fraction was 15%, the ammonium persulfate initiator dosage was 10%, the reaction temperature was 90°C, and the reaction time was 4 h. At a measured dose of 30 mg L−1, the scale inhibition impact on CaCO3 is 86.63%, while the scale inhibition impact on CaSO4 is 96.83%. The thermal properties of the copolymers, the crystal structure, and the micro‐morphology of the scale samples were analyzed by TGA, XRD, and SEM, and the scale inhibition mechanism was discussed in conjunction with the zeta potential analysis.

Interfacial Polymerization of Aromatic Polyamide Reverse Osmosis Membranes.

Polyamide membranes are widely used in reverse osmosis (RO) water treatment, yet the mechanism of interfacial polymerization during membrane formation is not fully understood. In this work, we perform atomistic molecular dynamics simulations to explore the cross-linking of trimesoyl chloride (TMC) and m-phenylenediamine (MPD) monomers at the aqueous-organic interface. Our studies show that the solution interface provides a function of "concentration and dispersion" of monomers for cross-linking. The process starts with rapid cross-linking, followed by slower kinetics. Initially, amphiphilic MPD monomers diffuse in water and accumulate at the solution interface to interact with TMC monomers from the organic phase. As cross-linking progresses, a precross-linked thin film forms, reducing monomer diffusion and reaction rates. However, the structural flexibility of the amphiphilic film, influenced by interfacial fluctuations and mixed interactions with water and the organic solvent at the solution interface, promotes further cross-linking. The solubility of MPD and TMC monomers in different organic solvents (cyclohexane versus n-hexane) affects the cross-linking rate and surface homogeneity, leading to slight variations in the structure and size distribution of subnanopores. Our study of the interfacial polymerization process in explicit solvents is essential for understanding membrane formation in various solvents, which will be crucial for optimal polyamide membrane design.

Rapid, Controlled Branching Polymerization of Cyanoacrylate via Pathway-Enabled, Site-Specific Branching Initiation.

Controlled branched structures remain a key synthetic limitation for monomeric tissue adhesives because their on-site polymerization that enables adhesion formation requires rapid kinetics, high conversion, and straightforward setup. In this context, site-specific branching initiation by using evolmers is potentially effective for structural control; however, the efficiency and kinetics in current reaction setups persists to be a major challenge. In this paper, an evolmer induces a controlled branching polymerization of cyanoacrylate amid the high monomer reactivity useful in rapid adhesion. The contrasting reactivities between the vinyl and the initiating groups in the evolmer molecule generate a kinetic pathway that favors a control-enabling branching mechanism. Through density functional theory calculations, the reaction pathway toward branching is shown to kinetically favor site-specific initiation by six orders of magnitude than the route toward non-specificity. Reaction monitoring confirms the branching polymerization after the polymerization with the evolmer forms a more compact structure than the linear counterpart. Control of branching density is demonstrated in rapid polymerizations within minutes and in polymerizations completed in an instant. These results provide a template for achieving site-specific branching initiation during adhesion formation and, broadly, where conditions for kinetic control are necessary.

Preparation and characterization of UV-Curable phosphate ester-containing acrylate resin adhesive for dental zirconia restorations

Fumed silica was utilized as a filler, methacryloyloxydecyl dihydrogen phosphate (MDP) served as a reactive monomer, and acrylate acted as a resin monomer to develop zirconia adhesives for dental acrylate resins containing phosphate esters. A uniform design, orthogonal tests, and single-variable experiments were conducted to vary the composition of each component. The effects of different composition ratios on the mechanical properties, hydrophilicity, flowability, and volumetric shrinkage of dental resin adhesives were studied in detail. The resin matrix composition included 43.6 wt% Bis-GMA, 28.2 wt% triethylene glycol dimethacrylate (TEGDMA), and 28.2 wt% hydroxyethyl methacrylate (HEMA). The photocurable system composition consisted of 4 % camphorquinone (CQ), 2.4 % ethyl 4-dimethylaminobenzoate (EDB), 3.2 % dimethylaminoethyl methacrylate (DMAEMA), and 1 % butylated hydroxytoluene (BHT). The adhesive monomer was 12 % MDP, and the filler system comprised 2 % R972 and 3 % OX50. The light curing time was set at 60 s. The adhesive exhibited optimal performance with a bonding strength of 35.9 MPa and a volumetric shrinkage of 13.3 %. According to this study, the proposed zirconia adhesive featuring a phosphate-containing acrylic ester group is a potential light-curing dental resin adhesive with a straightforward synthesis procedure, minimal volumetric shrinkage, good bonding strength, and an appropriate photocuring time.

Michael addition-elimination reaction derived covalent organic polyrotaxane xerogels for ultra-high-efficiency capture of iodine pollutants

Herein, covalent organic polyrotaxane xerogels (COPRs), were developed as comprehensive and recyclable “three birds with one stone” platform effectively handling organic/radioactive iodine pollutants challenges. COPRs were synthesized rapidly from β-ketoenamine and aromatic amines β-cyclodextrin (β-CD) inclusion via Michael addition-elimination reaction in water at room temperature and pressure, avoiding the usage of any organic solvents. The formation of β-CD inclusion significantly increases the solubility and reactivity of monomers in water. The threading of β-CD endows multiple absorption sites within the porous skeleton, improving its iodine capture capacity. The integration of β-CD ring throughout the carbon skeleton not only provides a green and ultra-low-cost approach for preparing COPRs with brand-new structure, but also offers direct and effective methods realizing the carbon neutrality from the source of production. This work could be used as a general method for the specifically modifying COPs, providing opportunities to meet the growing needs of society.

Gel dosimetry: An overview of dosimetry systems and read out methods

Gel dosimetry has emerged over the past three decades in response to a growing need in high-precision radiotherapy to assess, in three dimensions, the absorbed radiation dose, as would be administered in cancer patients.Radiation-induced reaction mechanisms are dependent on the class of gel dosimeter, with four classes emerging as primary dosimeters for use in radiation therapy dose verification: (i) Fricke gel dosimeters contain a Fricke solution consisting of ammonium iron (II) sulfate in an acidic solution of sulfuric acid. In Fricke systems an oxidation of ferrous ions results in a change in the nuclear magnetic resonance (NMR) relaxation rate, which enables reading out Fricke gel dosimeters by use of MRI. The radiation-induced oxidation in Fricke gel dosimeters can also be visualized by adding a redox indicator. (ii) Polymer gel dosimeters exploit the radiation induced polymerization reaction of vinyl monomers and are predominantly read out by quantitative MRI or X-ray CT. (iii) Radiochromic dosimeters do not demonstrate a significant radiation-induced change in NMR properties but can be scanned by use of optical scanners (optical CT). In contrast to Fricke gel dosimeters, radiochromic gel dosimeters do not rely on the oxidation of a metal ion but exhibit a color change upon radiation. (iv) Radiofluorogenic dosimeters become fluorescent when exposed to ionizing radiation and can be read out with a planar scanning light beam.Likewise, the imaging modality used to extract quantitative dose information depends on the class of dosimeter being used, and three primary imaging modalities have emerged in this context: quantitative MRI, x-ray CT, and optical CT imaging. The accuracy and precision of the dose information extracted from gel dosimetry systems depends on both the dosimetric properties of the gel dosimeters and the readout technique, and the optimal readout method depends on the gel dosimeter response.Despite remaining an active field of research and illustrations of the application of gel dosimetry for the validation of clinical dose distributions, the utilization of gel dosimetry as a routine clinical dosimeter has been rather limited. However, with the introduction of new radiotherapy techniques that focus on organ motion compensation, new fractionation schemes, and extreme dose rates, the need for 3D radiation dosimetry is apparent. Even with the need for 3D dosimetry being apparent, gel dosimetry faces continued challenges in areas regarding the extraction of reproducible, accurate, and precise dose information.This review paper focuses on an introduction to gel dosimeter classes; a detailed examination of the three readout techniques with emphasis on the achievable accuracy, precision, and optimization of readout parameters; an outlook on future applications in emerging new radiotherapy techniques. We note that the introduction of theragnostic hybrid MRI-Linacs that combine an MRI-scanner and a clinical linear accelerator create new opportunities for inline polymer gel dosimetry. Likewise, the use of cone beam CT on linear accelerators opens up the possibility to read out gel dosimeters on the linac. Multiple optical CT designs have shown that optical CT gel dosimetry is eminently capable of providing high quality dosimetric information from clinically relevant treatment regimes. As a result, gel dosimetry provides exciting opportunities for 3D radiation dosimetry that were not available even a few years ago. The unique feature set of a properly executed gel dosimetry workflow allows for the extraction of dosimetric information, in 3D, that is not possible with any other dosimetry system and hence gel dosimetry provides exciting opportunities for clinical and research work in the area of radiation dose measurement.

Fabrication of green xylose-based nanofiltration membrane with enhanced performance and chlorine resistance

Nanofiltration technology has been widely used in drinking water purification due to its excellent permeance and selectivity properties, especially in small molecular solute separation. However, using oxidizing agents in the pretreatment process for fouling control threatens the nanofiltration membrane structure, leading to the deterioration of the separation performance. Herein, we fabricate a polyester nanofiltration membrane utilizing xylose as an aqueous monomer in the interfacial polymerization process. Due to abundant hydroxyl groups and low reactivity of xylose monomers, the polyester membrane possessed a hydrophilic and thin separation layer, which led to high water permeance with the optimal value of 28.7 L·m−2·h−1·bar−1. Possessing highly cross-linking structures and negatively charged surfaces, the fabricated polyester membranes showed an excellent Na2SO4 rejection of up to 95.4 %. In addition, the low electron-donating property of polyester membranes ensured their chemical stability toward active chlorine. This endows relatively stable performance of the polyester membrane after chlorine resistance tests in a wide pH range. This study presents a feasible approach employing green monomers for fabricating nanofiltration membranes with outstanding separation performance and robust chlorine resistance.

Synthesis of well-defined poly(p-alkoxystyrene) by anionic polymerization in the presence of di-n-butylmagnesium

This study demonstrates the necessity of introducing di-n-butylmagnesium (n-Bu2Mg) additives to synthesize precisely controlled polymers through anionic polymerization of p-alkoxystyrene monomers at −40 °C. Without additives, 4-tert-butoxystyrene (BSt) and 4-(1-ethoxy ethoxy) styrene (EESt) are polymerized using sec-butyllithium (s-BuLi) in tetrahydrofuran (THF) solvent, yielding a molecular weight distribution (MWD) of 1.36. However, the MWD is strictly controlled to 1.05–1.06 after adding n-Bu2Mg in more than 30 times the amount of s-BuLi, resulting in an accurately designed molecular weight. Therefore, n-Bu2Mg effectively suppresses side reactions that could occur at the polymerization temperature of −40 °C in the Schlenk reactor. Interestingly, the polymerization reaction of styrene monomer proceeds when n-Bu2Mg is mixed in THF solvent at −40 °C for an extended period, even without s-BuLi. This result suggests that, despite being a weak anionic initiator, n-Bu2Mg can initiate polymerization due to the lower electron density of the styrene double bond compared to BSt or EESt. Based on these results, a precise copolymer with a narrow molecular weight distribution can be synthesized by initiating polymerization with s-BuLi within 20 s of adding n-Bu2Mg to the mixed monomers of styrene and EESt.

Effect of Solvents on the Performance and Structure of Polymethylacrylimide Aerogels.

Solvent effects play a critical role in solution polymerization, especially in free radical polymerization, where they influence both monomer-solvent interactions and the resulting polymer structure. In this study, polymethacrylimide (PMI) aerogels were synthesized via freeze-drying using dimethylformamide (DMF), dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO) as solvents. The effects of monomer reactivity ratios, monomer distribution, and solvent-monomer interactions on the shrinkage, bulk density, pore size, and compressive properties of the aerogels were investigated. Results demonstrated that solvent choice significantly impacted the polymerization process, leading to variations in the structure and properties of the final aerogels. Notably, aerogels synthesized in DMSO, the most polar solvent, exhibited the lowest shrinkage (33.98%), highest density (0.1582 g·cm-3), and highest compressive stress (1695.48 kPa at 70% strain). These findings underscore the importance of solvent selection in controlling the microstructure and enhancing the mechanical performance of PMI aerogels.

A N-heterocyclics induced π-π interaction strategy to synthesis hyper-crosslinked polymers with enhanced porosity for xenon adsorption

Hyper-crosslinked polymers (HCPs) with large specific surface areas play an important role in gas adsorption and separation. However, the method to enhance the specific surface area of HCPs and gas adsorption performance without changing the polyaromatic hydrocarbons (PAHs) monomer structure and reaction condition is still missing. Here, we present a general and facile N-heterocyclics induced π-π interaction strategy to increase the specific surface area of HCPs by simply adding N-heterocyclics during the Friedel-Crafts alkylation reaction. The specific surface areas of HCP (tetraphenylmethane based HCPs, TPMBPy-TCM) increased up to 7.78 times compared to the one without adding N-heterocyclics. The crosslinking and stacking of PAHs was influenced by the π-π stacking between the N-heterocyclic complexes and PAHs. More importantly, N-heterocyclics coordinated with Lewis acids have lower electron density and do not react with PAHs in the Friedel-Crafts alkylation reaction, which can be removed easily from HCPs. The HCPs obtained shown good xenon adsorption performance with Xe uptake of 3.63 mmol/g, which is the highest value for organic adsorbents reported in literature. This work provides new insight into the preparation of high-performance HCPs.

Mussel-inspired co-deposition of catechol-amine and graphene oxide (GO) modified anion exchange membranes (AEMs) for antifouling

Mussel-inspired co-deposition has many applications in surface modification of polymer membranes. Organic fouling of ion exchange membranes is one of the common issues that hinder electrodialysis treatment of industrial wastewater. In this work, anion exchange membranes were surface-modified by the mussel-inspired co-deposition of catechol-amine and graphene oxide (GO) nanosheets. Results showed that co-deposition with catechol (CA) and m-phenylenediamine (MPD) as reactant monomers rapidly generated modifying layer on the AEM surface. And the addition of GO into co-deposition helped improve the homogeneity and reduce polymer particle aggregation. The synergistic effect of catechol-amine and GO nanosheets was beneficial to form uniform modifying layer with improved hydrophilicity and negative charge density of membrane surface. In eletrodialysis experiments with sodium dodecyl benzene sulfonate (SDBS) as model foulants, GO-CA-MPD-3h modified AEM maintained high desalination rate close to that without folants, indicating good modifying antifouling performance. Mussel-inspired co-deposition of catecholamines and functional materials give new insights into membrane modificatin through a feasible and cost-effective method.

Vinyl methyl oxazolidinone and dimethyl itaconate as styrene substitutes for conventional high‐temperature unsaturated polyester resins

AbstractStyrene substitution is a major area of interest in the unsaturated polyester resins (UPR) industry and research. For most styrene‐free UPRs the unsaturated polyester (UP) formulation was tailored for less toxic reactive diluent monomers (RDM). The main challenge is finding a RDM that can directly substitute styrene in industrial UPR formulations without deterioration of resin and thermoset properties. Therefore, this study concerns vinyl methyl oxazolidinone (VMOX®) as a reactive diluent monomer for industrial high‐temperature UPRs. VMOX® and styrene were compared with dimethyl itaconate (DMI), methyl methacrylate, 2‐hydroxyethyl methacrylate, isobornyl methacrylate, triethylene glycol dimethacrylate and 1,4‐butanediol dimethacrylate. Further, the properties of produced resins and thermosets were investigated. The most striking result was comparable glass transition temperature, crosslink density, and residual monomer content of VMOX®‐ and styrene‐based thermosets. Subsequently, DMI was applied as a reactive co‐diluent for VMOX®‐based resins and thermosets. Significant improvement of VMOX® conversion during resin curing was observed. In conclusion, VMOX® is an excellent candidate for direct styrene substitution in industrial high‐temperature UPRs. Furthermore, the application of DMI as a reactive co‐diluent improves the reactivity of VMOX®‐based resins. The application of VMOX® and reactive co‐diluent monomer certainly creates new possibilities for direct styrene substitution in conventional UPR formulations.

Alkyne-rich patchy polymer colloids prepared by surfactant-free emulsion polymerization

While free radical polymerization methods are employed frequently to prepare sub-micron polymer particles, we hypothesized that surfactant-free emulsion polymerization (SFEP)11Surfactant-free emulsion polymerization methodology may prove beneficial for obtaining functional polymer particles by solution polymerization methods that preclude the need for conventional surfactants. To test the effectiveness of SFEP for the preparation of functional colloids, solution polymerization of several monomers, including propargyl acrylate (PA),22Propargyl acrylate. styrene (Sty)33Styrene. and tert-butyl acrylate (t-BA),44Tert-butyl acrylate. was performed over a range of monomer ratios and reaction scales. Electron microscopy and infrared spectroscopy were employed to evaluate the outcome of SFEP for particle size, shape, surface anisotropy, and chemical composition. Combining this characterization with optimized SFEP synthesis, we found that spherical polymer particles—homopolymers of PA as well as copolymers—were obtained in the 60–300 nm diameter size range. Successful inclusion of PA enabled the use of the particles in copper-catalyzed azide-alkyne cycloaddition reactions (CuAAc).55Copper-catalyzed azide-alkyne cycloaddition Moreover, electron microscopy characterization with backscattering revealed chemical and shape anisotropies on copolymer particles indicative of monomer phase-separation during particle formation. Overall, the SFEP methodology represents a straightforward, one-pot, bottom-up approach to yield a library of functional polymer particles, while avoiding undesirable aspects associated with conventional surfactants.

Dissecting the effect of substrate on polyamide reverse osmosis membranes via regulating substrate pore size by drying shrinkage

Several studies have proved that the substrate significantly influences the chemical properties of reverse osmosis (RO) membranes, whereas the underlying mechanisms remain elusive. Herein, we adjusted the substrate pore size from 8.6 nm to 4.4 nm by drying shrinkage, ensuring the substrate's chemical properties remained consistent. Interestingly, we observed that an intermediate pore size (7.4 nm) of the substrate resulted in the highest exotherm, with the interfacial temperature rising to 26.8 °C, thus showing that larger pore sizes do not necessarily result in more pronounced exothermic interfacial polymerization (IP) reactions. Through multiscale simulations and various characterization techniques, we found that the IP reaction is governed by two competing effects: (1) the storage capacity of MPD, which provides the reactive monomers; and (2) the water content, which absorbs the heat in the IP reaction. Balancing these two competing factors contributes to enhancing the diffusion of MPD, thereby promoting the progression of the IP reaction. This work revealed a new mechanism through which the substrate affects RO membrane formation.

Exploring the ring-opening metathesis polymerization process by kinetic Monte Carlo simulation

Investigating the kinetics of polymerization reactions is a powerful tool to obtain information for the engineering design of such processes. It provides insights into how the relative rates of elementary reactions which influence both the kinetics of the reactions and thus characteristics of the products as well, particularly when the reaction parameters of these reactions are unknown. Among polymerization processes, ring-opening metathesis polymerization (ROMP) has gained broad academic and industrial interest, due to its mild conditions to obtain a wide range of polymer products. In this study, kinetic Monte Carlo simulation was applied to reveal the effect of the elementary reactions of ROMP on the kinetics and product distribution. Both the propagation and the cross-metathesis reactions were considered, with the latter leading to the formation of various types of macrospecies whose population levels were also monitored. Relevant tendencies were observed regarding how the variations in the reaction parameters of the elementary reactions of this polymerization process, such as reaction probabilities, monomer addition method, catalyst-to-monomer ratio, and reaction time, affect the kinetics of the polymerization process and the product distributions. These variations also influence the key macromolecular parameters of the resulting polymeric materials, including chain length distribution (CLD), population levels, and polymer functionalities. The results of this study indicate that this simulation technique is a valuable tool for mapping the tailoring possibilities of modifying the reaction parameters of ROMP to achieve desired properties. These properties include number average molecular weight, polydispersity, chain end functionality, and macrocycle-free products.

Influence of castor oil‐derived bio‐resin on mechanical and visco‐elastic properties of dynamic covalent imine bond based epoxy and its composite

AbstractThe widespread use of thermoset composites has raised significant environmental and economic concerns due to their non‐recyclable nature. This study addresses these issues by developing vitrimers and their composites featuring dynamic imine bonds synthesized from vanillin, 3,3′‐dimethyl‐4,4′‐diaminodicyclohexylmethane, and epoxy. To enhance toughness and bio‐content in the vitrimer and its composites, a green reactive monomer, epoxy methyl ricinoleate (EMR), was synthesized via the transesterification of epoxidized castor oil (ECO) and incorporated as the reactive diluent. The effect of EMR on bio‐resin mechanical, thermo‐mechanical, and relaxation times (τ) of the vitrimer was examined. The inclusion of EMR reduced the relaxation time, indicating improved dynamic bond exchange efficiency. EMR incorporation decreased the relaxation time, suggesting enhanced efficiency in the interchange of dynamic bonds. In addition, the incorporation of 20% EMR increased the impact strength of the epoxy vitrimer by 37.8%. The study also details the manufacturing and characterization of greener composites made with these vitrimers and flax fabric, which were evaluated for various mechanical and thermo‐mechanical properties. Morphological analysis using a scanning electron microscope revealed good interfacial adhesion between the fiber and matrix. Furthermore, the flax fiber vitrimer‐based composite demonstrated effective chemical recyclability. The results indicate that these composites possess mechanical and thermal‐mechanical properties well‐suited for lightweight engineering applications.Highlights Recyclable vitrimers were developed from vanillin and epoxy. Toughness and bio‐content were enhanced by adding EMR. Relaxation time was reduced by EMR, improving bond exchange efficiency. Epoxy vitrimer impact strength was increased by 37.8% with 20% EMR. Green composites with vitrimers and flax fabric were manufactured.

Physico-mechanical characterization and DFT studies of benzoyl peroxide treated water hyacinth reinforced polypropylene composites

The use of eco-friendly natural fiber-reinforced polymer composites is rapidly expanding across diverse sectors. The rapid spread of water hyacinth disrupts aquatic ecosystems by modifying the pH of water and salinity in Bangladesh. This work investigated on the impact of incorporating both untreated and chemically treated water hyacinth fibers into polypropylene (PP). Untreated water hyacinth (UWH) powder was treated with an alkaline solution, producing mercerized water hyacinth (MWH). MWH was further oxidized to yield oxidized water hyacinth (OWH). Analysis of attenuated total reflection-fourier transform infrared (ATR-FTIR) spectra of UWH, MWH and OWH confirmed cellulose modification. The UWH and OWH were taken in varying contents (1, 2.5, 5, 7.5, and 10 wt%) and added to PP to make UWH-PP and OWH-PP composites using compression molding technique. The 1 % fiber content OWH-PP composites exhibited enhanced tensile strength, elongation, and impact strength compared to UWH-PP composites. Enhanced mechanical properties in OWH-PP composites suggested that benzoyl peroxide treatment improves interfacial adhesion. Morphological analysis of the OWH-PP composite showed better interfacial bonding between water hyacinth and PP than that of the UWH-PP composite. Thermogravimetric analysis (TGA) depicted the thermal stability of the UWH-PP and OWH-PP composites. The chemical reaction of cellulose monomer was further studied with DFT/B3LYP level of theory using two different basis sets 6-31+G(d, p) and cc-pVTZ. The calculated vibrational spectra of the untreated, mercerized and oxidized cellulose monomer agree well with the ATR-FTIR spectra, confirming chemical modification. DFT calculations of thermodynamic properties revealed the feasibility of the reactions. Electronic property (NBO charge) indicated charge transfer and structural changes during chemical modification.