Suspension Polymerization Process Research Articles

Monitoring batch suspension polymerization process based on calorimetric-state estimation technique

This work introduces an approach to enhance the real-time monitoring of batch suspension polymerization processes through the integration of real-time calorimetry and state estimation techniques. The challenges inherent in monitoring dynamic and complex processes, particularly in the absence of direct measurements, are effectively addressed through the proposed approach. A dynamic model equation specific to batch operation is employed to assess conversion throughout the process, with timely updates of dynamic parameters in the model equation. A nonlinear high gain cascaded observer with calorimetric measurements estimates the overall heat transfer coefficient and reaction heat. Variations in other parameters such as heat capacity and density are derived from estimated conversion data and updated in the model equation. The study also accounts for the heat loss to the surroundings during isoperibolic batch processes. Validation of the proposed soft sensor model is carried out by comparing the estimated and experimental conversion data by conducting MMA suspension polymerization in a reaction calorimeter. Results demonstrate the potential of calorimetric state estimation as an alternative to direct conversion measurements, offering comprehensive and enhanced monitoring of the batch suspension polymerization process.

Molecularly Imprinted Microspheres in Active Compound Separation from Natural Product.

Molecularly Imprinted Microspheres (MIMs) or Microsphere Molecularly Imprinted Polymers represent an innovative design for the selective extraction of active compounds from natural products, showcasing effectiveness and cost-efficiency. MIMs, crosslinked polymers with specific binding sites for template molecules, overcome irregularities observed in traditional Molecularly Imprinted Polymers (MIPs). Their adaptability to the shape and size of target molecules allows for the capture of compounds from complex mixtures. This review article delves into exploring the potential practical applications of MIMs, particularly in the extraction of active compounds from natural products. Additionally, it provides insights into the broader development of MIM technology for the purification of active compounds. The synthesis of MIMs encompasses various methods, including precipitation polymerization, suspension polymerization, Pickering emulsion polymerization, and Controlled/Living Radical Precipitation Polymerization. These methods enable the formation of MIPs with controlled particle sizes suitable for diverse analytical applications. Control over the template-to-monomer ratio, solvent type, reaction temperature, and polymerization time is crucial to ensure the successful synthesis of MIPs effective in isolating active compounds from natural products. MIMs have been utilized to isolate various active compounds from natural products, such as aristolochic acids from Aristolochia manshuriensis and flavonoids from Rhododendron species, among others. Based on the review, suspension polymerization deposition, which is one of the techniques used in creating MIPs, can be classified under the MIM method. This is due to its ability to produce polymers that are more homogeneous and exhibit better selectivity compared to traditional MIP techniques. Additionally, this method can achieve recovery rates ranging from 94.91% to 113.53% and purities between 86.3% and 122%. The suspension polymerization process is relatively straightforward, allowing for the effective control of viscosity and temperature. Moreover, it is cost-effective as it utilizes water as the solvent.

A Novel PolyHIPE‐like Catalyst for Esterification Reactions: on the Synthesis of Sulfonated Poly(styrene‐co‐n‐acylglycerol) and its Use for Efficient Conversion of Oleic Acid to Methyl Oleate

AbstractThe current work describes the synthesis of a new polyHIPE‐like sulfonated poly(styrene‐co‐n‐acylglycerol) and its use as an efficient heterogeneous catalyst to convert oleic acid into methyl oleate in esterification reactions. This new environmentally friendly polymer incorporates n‐acylglycerol macromonomer as a versatile strategy for glycerol valorization. Macroporous micrometric polymer particles are synthesized through suspension polymerization process without using porogenic agents. polyHIPE‐like copolymers formed with different feed compositions of styrene and n‐acylglycerol are chemically modified via sulfonation reactions to form a highly efficient catalyst for esterification of oleic acid to methyl oleate, exhibiting conversions lying in the interval from 52% to 96%, depending mainly on the amount of n‐acylglycerol macromonomer into the copolymer chains. The experimental results indicate the great potential of this new heterogeneous catalyst based on modified poly(styrene‐co‐n‐acylglycerol) to be successfully employed in esterification reactions of vegetable oils intended for the production of long chain alkyl esters of carboxylic acids, widely used as biofuels.

Ultrasonication-induced and diluent-assisted suspension polymerization for size-controllable synthesis of polydimethylsiloxane droplets

Submicroscale polydimethylsiloxane (PDMS) spheres are emerging as a promising solution for a variety of engineering applications due to their unique material properties and size. It is, however, still considered as challenging to produce submicroscale PDMS droplets. This leads to the need for development of a deterministic method for producing size-controllable, monodisperse PDMS droplets and, by extension, comprehensive understanding of the physicochemical players and processes involved in the synthesis method. Here, we develop an ultrasonication-induced and diluent-assisted (UIDA) suspension polymerization process to achieve the scalable synthesis of monodisperse PDMS droplets. The UIDA suspension polymerization process is essentially the same as conventional suspension polymerization processes except ultrasonic agitation and organic diluent addition. The use of ultrasonication is intended to controllably reduce the size of PDMS droplets, while the addition of a diluent to PDMS is designed to enhance the monodispersity of PDMS droplets (major) and decrease their size (minor). First, we explore the dependence of PDMS droplet size and polydispersity on rudimentary factors such as stabilizer (i.e., polyvinyl alcohol (PVA)), magnetic stirring, ultrasonication, diluent (i.e., benzene), and synthesis vessel. Next, a time-variant change in the size and size distribution of PDMS droplets under UIDA suspension polymerization process are investigated by deconvoluting the droplet dispersity in size into two components, each of which is described using an envelope of the log-normal distribution. The main cause of a bimodal distribution is also identified. Finally, we demonstrate the applicability of PDMS droplets in altering the hydrodynamic properties of polymer surfaces by fabricating a set of rose petal-inspired substrates through evaporation coating of PDMS droplets on flat PDMS surfaces. The findings of this study will lead to better understanding of suspension polymerization for synthesizing monodisperse submicroscale droplets made of thermosetting polymers.

Polymerization strategies to produce new polymer biocatalysts for the biodiesel industry

AbstractOne of the major challenges regarding the enzymatic production of biodiesel is the development of more robust, active, and stable immobilized biocatalysts. Thus, the present work aims to develop new enzymatic biocatalysts for use in esterification and transesterification reactions. New polymer supports based on poly(styrene‐co‐divinylbenzene) and poly(methyl methacrylate‐co‐divinylbenzene) platforms were synthesized, incorporating distinct functional compounds into the polymer chains (1‐octene, cardanol, and vinyl benzoate). Two distinct polymerization strategies were adopted for support syntheses: (i) Combined suspension and emulsion polymerization process (core‐shell particles); and (ii) Two‐step polymerization reaction comprising a suspension polymerization in presence of porogenic agents, followed by vacuum application (porous and nonporous particles). The obtained particles were employed for immobilization of lipase B from Candida antarctica. The addition of functional compounds resulted in particles with distinct textural properties. Moreover, particles with 91 m2.g−1 (P(MMA‐co‐DVB)/P(MMA‐co‐DVB)) were produced through combined suspension and emulsion polymerization, whilst particles with 154 m2.g−1 (P[MMA‐co‐DVB‐co‐VB]) were produced through suspension polymerization performed in presence of n‐heptane. Moreover, highly active biocatalysts were produced, leading to esterification conversions above 80%. Thus, based on the performance in esterification and transesterification reactions, the new functional matrices resulted in highly active biocatalysts with good potential for use in biodiesel industry.

Poly (Amidehydrazide) Hydrogel Particles for Removal of Cu2+ and Cd2+ Ions from Water.

Poly(amidoamine)s (PAMAM) are very effective in the removal of heavy metal ions from water due to their abundant amine and amide functional groups, which have a high binding ability to heavy metal ions. We synthesized a new class of hyperbranched poly(amidehydrazide) (PAMH) hydrogel particles from dihydrazides and N,N′-methylenebisacrylamide (MBA) monomer by using the A2 + B4 polycondensation reaction in an inverse suspension polymerization process. In Cd2+ and Cu2+ ion sorption tests, the synthesized dihydrazide-based PAMH hydrogel particles exhibited sorption capacities of 85 mg/g for copper and 47 mg/g for cadmium. Interestingly, the PAMH showed only a 10% decrease in sorption ability in an acidic condition (pH = 4) compared to the diamine-based hyperbranched PAMAM, which showed a ~90% decrease in sorption ability at pH of 4. In addition, PAMH hydrogel particles remove trace amounts of copper (0.67 ppm) and cadmium (0.5 ppm) in water, below the detection limit.

Multi-objective dynamic optimization of seeded suspension polymerization process

The temperature profile of the seeded suspension polymerization process was optimized to maximize molecular weight, shell thickness and monomer conversion ratio of core–shell polymer particles. Extreme learning machine radial basis function neural networks with R2 values greater than 0.93 were developed, to predict polymer properties at any point in time, using data generated by a computational fluid dynamics model. The optimal combination of input parameters for each neural network was selected from a pool of 44 variables, by using a weight-based method that uses a support vector regression model, and a global exhaustive search algorithm, consecutively. The neural networks developed were incorporated into a genetic algorithm that maximizes the molecular weight, monomer conversion ratio and shell thickness. The optimum temperature profile generated by the algorithm satisfactorily maximized all target polymer properties. This study also demonstrates that a support vector machine classifier could be reliably used for imposing nonlinear inequality constraints for solving dynamic optimization problems.

One-pot strategy for obtaining magnetic PMMA particles through ATRP using Fe(CO)5 as co-initiator

The first aim of this study was to develop an ATRP process for methyl methacrylate (MMA) polymerization using Fe(CO)5 as co-initiator. The kinetics analysis of the reaction in solution confirmed the controlled characteristic of the polymerization process. The process displays a slow initiation step and presents bimolecular termination reactions at higher molecular weights, confirmed by NMR analysis. Also, these observations are sustained by GPC, FT-IR, and XPS analyses, explaining the rather unusual dispersity values (1.4) for an ATRP reaction. The use of formic acid, which shifts the equilibrium towards Fe2+ species affording a quasi-controlled controlled polymerization process, is a key element in achieving control over the reaction. The Fe2+/Fe3+ ratio at the end of the reaction, determined by XPS analysis, suggests the possibility to generate magnetic iron oxide particles. Therefore, the synthesis strategy was adapted for use in the suspension polymerization process of MMA which permitted the production of magnetic PMMA particles through a facile one-pot approach, using only an ammonia treatment stage. The obtained PMMA particles, characterized by SEM, XPS, TEM, TGA, and XRD analyses, have porous characteristics and magnetic properties which makes them good candidates as catalyst supports, separation processes, or biomedical applications.

Characterization and oil recovery enhancement by a polymeric nanogel combined with surfactant for sandstone reservoirs

The characterization and enhanced oil recovery mechanisms of a nanosized polymeric cross-linked gel are presented herein. A negatively charged nanogel was synthesized using a typical free radical suspension polymerization process by employing 2-acrylamido 2-methyl propane sulfonic acid monomer. The synthesized nanogel showed a narrow size distribution with one peak pointing to a predominant homogeneous droplet size. The charged nanogels were also able to adsorb at the oil–water interfaces to reduce interfacial tension and stabilize oil-in-water emulsions, which ultimately improved the recovered oil from hydrocarbon reservoirs. In addition, a fixed concentration of negatively charged surfactant (sodium dodecyl sulfate or SDS) was combined with different concentrations of the nanogel. The effect of the nanogels combined with surfactant on sandstone core plugs was examined by running a series of core flooding experiments using multiple flow patterns. The results show that combining nanogel and SDS was able to reduce the interfacial tension to a value of 6 Nm/m. The core flooding experiments suggest the ability of the nanogel, both alone and combined with SDS, to improve the oil recovery by a factor of 15% after initial seawater flooding.

A versatile route to the synthesis of pressure-sensitive adhesives and polyHIPE-like microparticles: an experimental study on glycerol valorization

This present work focuses on the synthesis of styrene / n-acylglycerol (n-ACG) (a macromonomer formed by glycerol esterification with acrylic acid catalyzed by methane sulfonic acid) copolymers through suspension polymerization process. The final properties of poly(styrene-co-n-acylglycerol) was strongly dependent on the n-ACG fraction into the polymer chains. The effect of n-ACG on the copolymer properties was evaluated and a huge reduction in both the thermal stability and the Tg values (from 93 °C for polystyrene homopolymer to −22 °C for styrene / n-ACG copolymers synthesized with 20 wt% of n-ACG) was observed when the n-ACG fraction was increased. The variations in the thermal properties were accompanied by drastic morphological changes of the materials, depending essentially on the n-ACG composition as for instance: i) porous spherical particles with polyHIPE-like structures (copolymers containing from 5 to 15 wt% of n-ACG), which indicates that these porous microparticles may be used as support/carries in heterogeneous catalysis, ion exchange resins, and controlled drug delivery, among others; ii) adhesive films containing n-ACG fractions higher than 15 wt%, conferring "tack" features similar to the one observed in for pressure-sensitive adhesives (PSA) evaluated by using a rolling ball test. Mechanical tests also showed that the polymer adhesives have an enormous potential to be used as PSA materials in the adhesive industry.

Development of self-contained microcapsules for optimised catalyst position in self-healing materials

Self-contained microcapsules for use in self-healing epoxy resin are successfully synthesized by suspension polymerization process. The microencapsulation of an epoxy resin using Polymethylmethacrylate (PMMA) as a shell material and the location of scandium triflate (Sc(OTf)3) as the catalyst into microcapsules shell during the microencapsulation processes is presented (PMMA/Sc(OTf)3-walled microcapsules). Spherical microcapsules of 80 μm in diameter with a liquid core content of 30 wt% (determined by HPLC) are produced. Catalyst location on microcapsules are assessed qualitatively by SEM-EADS and quantitatively by TGA showing high yields (⁓70 wt%). The evaluation of the healing efficiency was assessed in terms of fracture toughness recovery. PMMA/Sc(OTf)3-walled microcapsules showed an increased healing efficiency than that of conventional PMMA-walled capsule. The healing efficiency of the PMMA-walled capsules was 46.7 and 55.1% when the system healed at 80 and 120 °C, respectively. However, in the case of PMMA/Sc(OTf)3-walled microcapsules healing efficiency increased to 57.5 and 79.1% for the same healing temperatures.

Particle size distributions of P(VAc-co-MMA) beads produced through nonconventional suspension copolymerizations II. Use of focused beam reflectance measurements for in-line monitoring of chord size distributions

The use of polymer beads in biomedical applications has increased significantly over the past few years. In some of these applications, such as vascular embolization (VE), the control of particle size distributions (PSD) is of fundamental importance to assure safe and reproducible biomedical results. Particularly, polymer beads intended for biomedical applications are frequently produced through suspension polymerization processes, which can be monitored in-line with help of Focused Beam Reflectance Measurements (FBRM), which can provide chord size distributions (CSD) and PSDs in real time. For this reason, the FBRM technique is used here for the first time to monitor suspension polymerizations performed in semibatch mode and in the presence of small amounts of inhibitors, as these nonconventional suspension polymerization processes allow for production of polymer particles with narrower PSDs [1]. It is shown here that suitable combination of these nonconventional techniques may allow for faster stabilization of the CSDs of suspended particles, keeping the CSDs (and PSDs) approximately constant during longer periods of the batch time. The faster stabilization of rates of breakage and coalescence of suspended particles in the initial reaction trajectory probably explains the narrower PSDs of the final particles.

Effect of the operating conditions on the particle size distribution by the suspension polymerization process

In this research, we focus on the study of the operating conditions that influence on suspension process for obtaining (co)polymers of styrene with polar monomers (copolymers of styrene with acrylate of butyl (S-BA) and copolymers of styrene with vinyl acetate (S-VAc)) using the technique of conventional free radical polymerization (FRP). At higher agitation speed, the reaction performance decreases. Likewise, the influence of the molecular weight of the dispersing agent, in this case polyvinyl alcohol (PVA), influences the polymerization performance was also observed. That is, at a higher molecular weight of PVAs, there is an increase in the particle size of the bead and in the polymerization yield. Finally, there is an influence of the polar part on the copolymer both for the yield and for the particle size of the bead. When obtaining copolymers of S-VAc, the yield is lower compared to the respective styrene homopolymer and higher in the S-BA.

Influence of zinc oxide in a polar polymer matrix

The creation of films constituted by semiconductor oxides of zinc oxide (ZnO) incorporated into a polar polymer matrix was proposed, looking for such films to be easy to apply, friendly to the environment and compatible with materials. Within the experimental process, the synthesis of styrene copolymers with a polar monomer (methyl methacrylate) was carried out through the suspension and emulsion polymerization processes.

Highly Magnetizable Crosslinked Chloromethylated Polystyrene-Based Nanocomposite Beads for Selective Molecular Separation of 4-Aminobenzoic Acid.

In this work, we describe the preparation and characterization of highly magnetizable chloromethylated polystyrene-based nanocomposite beads. For synthesis optimization, acid-resistant core–shelled maghemite (γ-Fe2O3) nanoparticles are coated with sodium oleate and directly incorporated into the organic medium during a suspension polymerization process. A crosslinking agent, ethylene glycol dimethacrylate, is used for copolymerization with 4-vinylbenzyl chloride to increase the resistance of the microbeads against leaching. X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and optical microscopy are used for bead characterization. The beads form a magnetic composite consisting of ∼500 nm-sized crosslinked polymeric microspheres, embedding ∼8 nm γ-Fe2O3 nanoparticles. This nanocomposite shows large room temperature magnetization (∼24 emu/g) due to the high content of maghemite (∼45 wt %) and resistance against leaching even in acidic media. Moreover, the presence of superficial chloromethyl groups is probed by Fourier transform infrared and X-ray photoelectron spectroscopy. The nanocomposite beads displaying chloromethyl groups can be used to selectively remove aminated compounds that are adsorbed on the beads, as is shown here for the molecular separation of 4-aminobenzoic acid from a mixture with benzoic acid. The high magnetization of the composite beads makes them suitable for in situ molecular separations in environmental and biological applications.

Synthesis of superabsorbent carbonaceous kenaf fibre filled polymer using inverse suspension polymerisation

This paper studies the synthesis of superabsorbent carbonaceous kenaf fibre filled polymer using inverse suspension polymerisation method. The kenaf fibre was prepared using the hydrothermal carbonisation process. Inverse suspension polymerisation process involved two different solution mixtures; a continuous phase containing cyclohexane, span-80, and kenaf fibre filler and a dispersed phase containing partially neutralised acrylic acid, acrylamide, initiator APS, and crosslinker NN-Methylenebisacrylamide. Kenaf fibre filler addition was varied with different weight percentages (0.01- 0.05 wt%). Water absorption testing using the teabag method showed sample containing 0.04 wt% carbon filler had the highest and optimal percentage of water absorbency, 55.27 g/g while the sample containing 0.01 wt% carbon filler displayed the lowest percentage of water absorbency, 45.27 g/g. All SPC samples showed a higher rate of water absorbency compared to SAP sample which had 40.61 g/g of average water absorbency. The samples were characterised by FTIR, FESEM - EDX, Mastersizer. All synthesised samples produced were in spherical beads form. It can be concluded that kenaf fibre affects the enhancement of superabsorbent polymer performance.

Cross Linking Between the Baffling Effect and Phase Inversion During Liquid–Liquid Monomer Mixing

Recent studies have revealed unexpected developments in drop size by only small changes in the geometrical constraints of batch vessels used for suspension polymerization. The effect of the dispersed phase fraction, surfactant concentration, as well as baffle length on the evolving drop size distribution in different low viscous liquid–liquid systems is investigated. The analysis is focused on the drop‐dominated systems by hindering the coalescence by polyvinyl alcohol (PVA) concentrations up to three times higher than the critical micelle concentration. The influence of PVA on drop size in breakage‐dominated systems is well reproduced with population balance equation simulations. The drops are measured using a photo‐optical system with automated image analysis. The measured drop sizes increase with increasing dispersed phase fraction. As coalescence is completely hindered, all observed coalescence effects are connected to phase inversion, a catastrophic phenomenon during suspension polymerization for industrial production processes. Phase inversion can be reproduced for all studied solvents with and without the use of surfactants. In particular, the influence of the baffles can be reproduced. The system is adapted and trained to detect phase inversion as a warning system to make the suspension polymerization process more stable and robust. image

Multiscale Computational Fluid Dynamics–Population Balance Model Coupled System of Atom Transfer Radical Suspension Polymerization in Stirred Tank Reactors

Partially water-soluble monomers achieve phase equilibrium between aqueous and dispersed phases, and the interphase mass transfer plays a significant role in suspension polymerization. This work developed a computational fluid dynamics model to simulate the liquid–liquid suspension polymerization process. Complex multiphase flow behaviors and multiscale polymer properties were simultaneously simulated using the combination of an Eulerian–Eulerian two-phase flow model, an atom transfer radical polymerization kinetics model, a population balance model (PBM), and an interphase transfer model. The simulation results for monomer conversion, molecular weight (Mn), polydispersity index (PDI), and Sauter mean diameter (d32) agreed well with the experimental data, thereby validating the soundness of the multiscale model. The proposed model was then employed to predict key variables of the polymerization system. The coupled model can benefit the optimization and scale-up of suspension polymerization reactors with s...

Target Delivery from Modified Polymers to Cancer Treatment

Several kinds of polymeric particles designed for drug delivery purposes can be successfully synthesized via heterogeneous polymerization processes. Due to the high ability to produce tailor-made polymers, suspension, mass-suspension, suspension-emulsion, miniemulsion and emulsion polymerization processes deserve special attention in the drug delivery field, as the process operating conditions play a significant role on both the morphology and the macromolecular architecture of the polymeric materials. The present paper also focuses on the main features of important polymer system used in drug delivery, as well as, the cancer therapy, exploring the receptor-based targeting of therapeutics and the cancer recognition mechanisms given special attention to the combined action of immunotherapy and chemotherapy. Dissolution models are also discussed due to their importance to the prediction of the dissolution process and drug release in the blood, providing fundamental insight into the dissolution profiles of the drug along the treatment time. Keywords: Target delivery, polymers, cancer treatment, polymerization processes, drug delivery system, dissolution models.

MODELING PARTICLE SIZE DISTRIBUTION IN HETEROGENEOUS POLYMERIZATION SYSTEMS USING MULTIMODAL LOGNORMAL FUNCTION

Abstract - This work evaluates the usage of the multimodal lognormal function to describe Particle Size Distributions (PSD) of emulsion and suspension polymerization processes, including continuous reactions with particle re-nucleation leading to complex multimodal PSDs. A global optimization algorithm, namely Particle Swarm Optimization (PSO), was used for parameter estimation of the proposed model, minimizing the objective function defined by the mean squared errors. Statistical evaluation of the results indicated that the multimodal lognormal function could describe distinctive features of different types of PSDs with accuracy and consistency. Keywords : Particle Size Distribution; Lognormal function; Parameter estimation; Particle Swarm Optimization; Heterogeneous polymerization. INTRODUCTION The particle size distribution (PSD) is one of the most important characteristics of polymer latexes/res-ins, since properties such as viscosity, maximum solids content, adhesion and drying time depend on the profile of this distribution (Vale and McKenna, 2005). Furthermore, the understanding of the dynam-ics of PSD is very important for process monitoring and final quality control of heterogeneous polymeri-zation processes (Hosseini