Thermal analysis of interpenetrating polymer networks through molecular dynamics simulations: a comparison with experiments

International audienceIn this work, we verified the synthesis of a novel sequential interpenetrating polymer network, composed of poly(2-hexyl-ethylacrylate) and poly(n-butyl acrylate) named PHEA and PBuA, respectively, and we studied the physical properties by means of thermogravimetric analysis and differential scanning calorimetry techniques. An increase in the thermal stability is found with the increase in the density of the polymer network, and the amount of the absorbed monomer by the network has a great influence on its behavior and glass transition temperature. We supplement this job by applying molecular dynamics simulation methods (free volume, radial distribution function) to investigate the properties of these polymer networks and effects of composition ratios and temperature by introducing a new comprehensive and reproducible atomistic model for the generation and property evaluation of interpenetrating polymer networks. The simulation presented from the discontinuity in the different plots versus temperature of the specific volume or radial distribution function, demonstrates that the glass transition temperature (Tg) values were in good agreement with experimental values

Caractérisation de différents réseaux de polymères en présence de solvants isotropes et anisotropes

La caractérisation des réseaux de polymères, obtenus par photopolymérisation radicalaire, a été faite par gonflement en masse du réseau de poly(n-butylacrylate) dans des solvants organiques isotropes. L étude a montré que le taux de gonflement dépend à la fois de la nature du solvant, de la densité de réticulation ainsi que de la température. Ce dernier paramètre influe seulement sur les réseaux gonflés dans des mauvais solvants, comme par exemple le méthanol. L étude a été suivie d une caractérisation par gonflement en volume des réseaux de poly(n-butyl-acrylate) et de poly(2-éthyl-hexyl-acrylate) dans des solvants anisotropes, tels que les cristaux liquides 5CB et E7. L analyse a été effectuée par microscopie optique dans une grande plage de température. Le E7 présente une meilleure compatibilité avec le PABu qu avec le PEHA. Le 5CB a une miscibilité supérieure à celle du E7 dans le PABu. L étude comparative de gonflement dans des solvants isotropes et anisotropes a mis en évidence, qu en termes de miscibilité, les cristaux liquides E7 et 5CB se situent entre le toluène comme bon solvant isotrope, et le méthanol, comme mauvais solvant isotrope. Le modèle de diffusion de Fick a été appliqué aux résultats expérimentaux de cinétique de gonflement des systèmes polymères isotropes et solvants isotropes . Une méthode d optimisation a été utilisée qui consiste à déterminer les facteurs influant sur le gonflement et la réponse quand ces facteurs varient. A partir d un minimum d expériences, on aboutit à une surface de réponse qui couvre toute la gamme de l étude. La méthode utilisée est le plan d expériences factoriel 2k.The characterization of polymer networks, obtained by radical photopolymerization, was made by swelling of the network of poly (n-butylacrylate ) in isotropic organic solvents. The study showed that the swelling rate depends on the nature of the solvent, on the density of crosslinking as well as on the temperature. This last parameter influences only networks swollen in bad solvents, such as methanol. The study was followed by a characterization by swelling in volume of the networks of poly (n-butyl-acrylate ) and of poly (2-ethyl-hexyl-acrylate) in anisotropic solvents, such as the liquid crystals 5CB and E7. The analysis was made by optical microscopy on a large range of temperature. E7 presents a better compatibility with the PABu than with the PEHA. 5CB has a higher miscibility to that of E7 in PABu. The comparative study of swelling in isotropic and anisotropic solvents put in evidence, that in terms of miscibility, the liquid crystals E7 and 5CB are situated between the good isotropic solvent toluene and the bad isotropic solvent methanol.The model of diffusion of Fick was applied to the experimental results of swelling kinetics of the systems " isotropic polymers and isotropic solvents ". A method of optimization was used which consists in determining the factors influencing the swelling and the answer when these factors vary. From a minimum of experiments, we end up in a surface of answers which covers the whole range of the study. The used method is the factorial plan of experiments 2k.LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF

Swelling and thermal behavior of a cross-linked polymer networks poly(2-phenoxyethyl acrylate): exploitation by the Voigt viscoelastic model

International audienceThe response-ability to the external and internal environmental condition qualifies the smart polymer material to be successfully applied in artificial muscle, drug delivery and water treatment. A three-dimensional polymer network based on the phenyl monomer, 2-phenoxy ethyl acrylate (PEA), was polymerized under ultraviolet (UV) radiation using the Darocur 1173 as an initiator of the polymerization reaction, and the 1,6-hexane-diol diacrylate (HDDA) as a chemical cross-linker. The analysis of the thermophysical properties of this elaborated polymeric material represents the main goal of the present work. The infrared spectroscopy (FTIR) and the dynamic scaling calorimetry (DSC) were used to examine, respectively, the vibration of the carbon double bond (C=C) and the glass transition temperature Tg. It is found that parameters, the rate of reticulation and monomer composition have a remarkable effect on the variation of Tg. The swelling behavior of the cross-linked poly(PEA/HDDA) was investigated; the effects of solvent nature, the degree of cross-linking, temperature and chemical structure have a significant influence on material swelling properties. The theoretical investigation based, especially on the Voigt model, Flory–Rehner theory and solubility approximation, permits to give much information about several parameters such as the swelling time constant, swelling equilibrium constant, solubility prediction, entropy and enthalpy. It ended interestingly that the Voigt model shows a good agreement with swelling experimental results

Novel interpenetrating polymer network composed of poly(butyl acrylates) and poly(ethyl-hexyl acrylate)

International audienceNovel full acrylic interpenetrating polymer networks (IPNs) made up of thePoly Ethyl- Hexyl Acrylate (PEHA) and Poly Butyl-Acrylate (PABu) networkswith various crosslinking ratios were characterized by means of Infraredspectroscopy, swelling, DSC and TGA techniques. The systems are preparedvia photo-polymerization by UV-curing of monomers in the presence of adifunctional crosslinker and a photo-initiator. The physical properties of theIPNs are mainly influenced by the quantity of the monomer present in theIPNs and increasing the crosslinker prevents formation of unreactedoligomers inside the IPNs. Surprisingly, the IPNs with 0.5% crosslinker doesnot present any phase separation

Kinetic analysis of the swelling behavior of poly(butylacrylate-1,6-hexanedioldiacrylate) networks in 4-cyano-4-pentyl-biphenyl (5CB)

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Conformational modeling of the system pollutant/three-dimensional poly (2-hydroxyethyl methacrylate) (PHEMA) in aqueous medium: a new approach

International audienceThe polluted water, mixture of chemicals and dyes, discharged by various textile and paper industries, is a serious problem for the environment, peculiarly the water. Dyes are stable to light, heat and oxidizing agents and are usually biologically non-degradable, which makes them complicated environmental pollutants. To examine the removal of dye from water, a three-dimensional poly (2-hydroxyethyl methacrylate) (PHEMA) and eosin Y were used, respectively, as a dye retention support and pollutant. The study of the interaction between dye and a hydrophilic polymer networks by the conformational modeling using computer software represents the goal of the present work. Both the swelling and ultraviolet–visible spectrophotometry studies show that the pollutant was well retained by the porous polymer network PHEMA. The conformational study of the system composed of polymer network/dye shows that the interaction of the oxygen (O) and bromine (Br) of eosin Y with the hydrogen (H) of the PHEMA depends on the polymer porosity that was varied by the cross-linking rate of the three-dimensional polymer networks. The results obtained by this work can be applied to improve the retention efficiency of such material for use in wastewater application

Cleaning of Wastewater Using Crosslinked Poly(Acrylamide-<i>co</i>-Acrylic Acid) Hydrogels: Analysis of Rotatable Bonds, Binding Energy and Hydrogen Bonding

The discharge of untreated wastewater, often contaminated by harmful substances, such as industrially used dyes, can provoke environmental and health risks. Among various techniques, the adsorption of dyes, using three-dimensional (3D) networks consisting of hydrophilic polymers (hydrogels), represents a low-cost, clean, and efficient remediation method. Three industrially used dyes, Methylene Blue, Eosin, and Rose Bengal, were selected as models of pollutants. Poly(acrylamide) (poly(AM)) and poly(acrylamide-co-acrylic acid) (poly(AM-co-AA)) networks were chosen as adsorbent materials (hydrogels). These polymers were synthesized by crosslinking the photopolymerization of their respective monomer(s) in an aqueous medium under exposure to UV light. Experimental adsorption measurements revealed substantially higher dye uptakes for poly(AM-co-AA) compared to poly(AM) hydrogels. In this report, a theoretical model based on docking simulations was applied to analyze the conformation of polymers and pollutants in order to investigate some aspects of the adsorption process. In particular, hydrogen and halogen interactions were studied. The presence of strong hydrogen bonding plays a crucial role in the retention of dyes, whereas halogen bonding has a small or negligible effect on adsorption. An evaluation of binding energies allowed us to obtain information about the degree of affinity between polymers and dyes. The number of rotatable bonds in the copolymer exceeds those of poly(AM),meaning that poly(AM-co-AA) is revealed to be more suitable for obtaining a high retention rate for pollutants

Analysis of dynamic mechanical properties of photochemically crosslinked poly(isobornylacrylate-co-isobutylacrylate) applying WLF and Havriliak-Negami models

International audienceChemically crosslinked poly (isobornylacrylate-co-isobutylacrylate) was elaborated by radical photo-copolymerization of isobornylacrylate and isobutylacrylate monomers in a 4:1 mass ratio, by adding a crosslinking agent at low concentration. The obtained copolymer was characterized by Fourier transform infrared spectroscopy for structural analysis, by differential scanning calorimetry for the determination of the glass transition temperature, and by thermogravimetric analysis to investigate thermal degradation effects. Storage modulus, dissipation modulus and tan delta were evaluated by dynamic mechanical analysis and modeled using different physical approaches such as the time-temperature superposition principle and the Havriliak-Negami model. The Cole-Cole curve was fitted with the Havriliak-Negami model yielding five parameters which were used to calculate the dynamic mechanical properties of the copolymer over a large frequency range from 1.03 × 10−4 Hz to 7.58 × 107 Hz. Calculated elastic and dissipative moduli agree well with the experimental data

An Interpenetrating Polymer Network Hydrogel Based on Cellulose, Applied to Remove Colorant Traces from the Water Medium: Electrostatic Interactions Analysis

The main objective of this work was the removal of eosin Y and green malachite from an aqueous medium by using a cellulose-based biodegradable interpenetrated network (IPN). The IPN was obtained by the sequenced synthesis method. In the first step, cellulose was crosslinked with epichlorohydrin (ECH). In the second step, the obtained gels were swollen in a reactive mixture solution, which was based on the monomers 2-hydroxyethyl methacrylate (HEMA) and 1,6- hexanediol diacrylate (HDDA). After this, swelling equilibrium was reached through the gels’ exposition to UV radiation. An infrared spectroscopy (FTIR) was used to analyze the bond stretching, which confirmed the IPN’s formation. The swelling kinetics in aqueous mediums with different pH values showed a high swelling at a basic pH value and a low response in neutral and acidic media. The IPNs showed an improvement in water uptake, compared to the networks based on PHEMA or cellulose. The IPN was used to remove dyes from the water. The results showed that a high percentage of green malachite was removed by the IPN in six minutes of contact time. The experimental results were confirmed by the docking/modeling method of the system (IPN/Dye). The different physical interactions between the IPN and the dyes’ molecules were investigated. The interactions of the hydrogen bonds with malachite green were stronger than those with eosin Y, which was in good agreement with the experimental results