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DOI: 10.1007/12\₂014\₃02; International audience; Use of microwave energy to heat and drive chemical reactions has been an increasingly popular theme in the scientific community. Historically, since the 1950s microwave energy has become an essential part of many technical applications in chemical and related industries, particularly in organic chemistry. However, microwave heating was not introduced to polymer chemistry until the mid-1980s. Regardless of the exact nature of the still-debated microwave effects, microwave synthesis has now truly matured and has moved from a laboratory curiosity to an established technique in both academia and industry. Among the polymerization techniques, controlled radical polymerizations (CRPs) are known to produce high-value products with controlled architecture and low dispersity. Original physicochemical properties and promising applications are reachable. This chapter provides, in a concise form, a current picture of three types of microwave-assisted controlled radical polymerization (RAFT, NMP, ATRP) with regard to the irradiation mode and the activation energy values. © Springer International Publishing Switzerland 2014.

International audience

cited By 5; International audience; The copoly(2-oxazoline) pNonOx80-stat-pDc=Ox20 can be synthesized from the cationic ring-opening copolymerization of 2-nonyl-2-oxazoline NonOx and 2-dec-9′-enyl-2-oxazoline Dc=Ox in the ionic liquid n-hexyl methylimidazolium tetrafluoroborate under microwave irradiation in 250g/batch quantities. The polymer precipitates upon cooling, enabling easy recovery of the polymer and the ionic liquid. Both monomers can be obtained from fatty acids from renewable resources. pNonOx80-stat-pDc=Ox20 can be used as polymer in a photoresist (resolution of 1μm) based on UV-induced thiol-ene reactions. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

cited By 4; International audience; We propose an exhaustive experimental characterization of a series of poly(n-butyl acrylate) samples that were synthesized by controlled radical polymerization and have different molecular weights. We focus on the rheological behavior of these polymers and propose a model of their rheological behavior using a molecular model based on the reptation concept. We report the principal rheological parameters for these homopolymers and demonstrate good agreement between model predictions and experimental data

cited By 27; International audience; We performed a critical reinvestigation of microwave enhancement of nitroxide-mediated polymerization (NMP) of acrylamide (AM) in aqueous media in the dynamic (DYN) mode with a combination of a conventional hydrosoluble radical initiator and a β-phosphonylated nitroxide (SG1). Based on the results of our previous work, a complementary series of polymerization reactions was carried out between 130 and 160 °C using only the DYN mode to ascertain the existence of a microwave effect. The polymer conversion (p), molar masses, polydispersity index, and viscosity of each sample were measured. The temperature was monitored inside and outside of the vessel using an optical fiber sensor and an IR sensor, respectively. Microwave enhancement of polymerization, temperature control and viscosity of the reaction media were closely related. We also furthered the field of hydrophilic AB diblock copolymer synthesis using a tertiary SG1-based macroalkoxyamine and directly synthesized both poly(acrylamide-b-sodium 2-acrylamido-2-methylpropanesulfonate), a neutral-b-anionic diblock copolymer, and poly(acrylamide-b-3- dimethyl(methacrylamidopropyl)ammonium propanesulfonate), a neutral-b- zwitterionic diblock copolymer, in homogeneous aqueous media.

cited By 16; International audience; A recently introduced online monitoring technique allows monomer conversion f, weight average polymer mass Mw, and reduced viscosity ηrto be continuously monitored without any chromatographic columns during polymerization reactions. This technique was adapted to a Homogeneous Continuous Stirred Tank Reactor (HCSTR) to verify the quantitative predictions concerning f, Mw, and ηr, as a function of the flow and kinetic parameters, to determine the kinetic parameters themselves, to ascertain the ideality of mixing in the reactor, to assess the effects of feed and reactor fluctuations, and to approximate a fully continuos tube type reactor. The synthesis of polyacrylamide was chosen as a practical system for the investigation. The online method should be a useful experimental technique for basic kinetic studies, development of new materials assessment of reactor performance, verification of model studies, and monitoring of industrial scale reactors.

cited By 53; International audience; The influences of NaCl on the steady rheological behaviour of aqueous solution were investigated for a hydrophobically modified polyacrylamide (HMPAM) and its hydrolyzed derivatives (HHMPAM) prepared by post-modification. The apparent viscosity (ηapp) and reduced viscosity (ηred) were measured as a function of NaCl content. As salinity increased, ηred decreased for both HMPAM and HHMPAM in dilute regime; in the semidilute solution, a continuous increase of ηred was observed for HMPAM while ηred passed through a minimum in the case of HHMPAM. At a given polymer concentration in semidilute regime, both shear thickening and anti-thixotropic properties were observed as a function of salinity and hydrolysis degree, as well as ageing time. Dilatancy was observed over a range of shear rates beyond which solutions behaved as classical polymer systems. When salinity exceeded a critical value, dilatancy and anti-thixotropy appeared as increasing functions of ionic strength and decreasing functions of hydrolysis degree. Prolongation of ageing time strongly enhanced both shear thickening and anti-thixotropic behaviors. These results are interpreted by the changes of the relative numbers of intra- and intermolecular associations, and the participation of free hydrophobes in the formation of clusters under shear. © 2002 Society of Chemical Industry.

cited By 22; International audience; A recently introduced, automated method for online monitoring of polymerization reactions was used to study free-radical transfer reactions. The persulfate initiated polymerization of acrylamide (AAm) in water was chosen as the test system. Chain transfer properties of ethanol (EtOH) and propanol (PrOH) were investigated. Different methods of computing the transfer constant are compared, including those based on the slope and intercept behavior of the monitored cumulative weight-average molecular mass as a function of conversion, Mw(f), the reduced viscosity, and corresponding size exclusion chromatography analysis of the reaction end products. To a close approximation, the chain transfer agents were found to obey the form expected when ideal free-radical polymerization takes place and radical transfer from propagating radicals to the chain transfer agent (CTA) is slower than from the CTA to monomer, that is, the polymer molar mass decreases with increasing chain transfer agent but there is no appreciable effect on the kinetics of monomer conversion. The AAm kinetics were characterized in terms of the ratio kp2/kt, where and kp and kt are the propagation and termination rate constants, respectively.

International audience; Chemical EOR polymers are in general anionic, synthetic, acrylamide based co-and ter-polymers. Those polymers provide viscosity to water based system thanks to their high molecular weight (Mw) and the repulsions between the ionic charges. Uncoiling and entanglements are the two mechanisms linked to Mw and ionic repulsion. When a polymer is injected, different mechanisms will act on its chemical structure by chemical, mechanical, thermal, free radical modifications. The understanding of the resulting rheological properties of the modified PAM is very important since it can change the control over the mobility ratio when it propagates downhole in the reservoir. Various lab experiments can be performed to predict those changes over time. In particular, the intrinsic viscosity is a convenient way of reaching the dimension of the macromolecule in a given solvent and at a given temperature but is time consuming. In this publication, a new and efficient capillary rheology technique is presented allowing measuring the bulk solution rheology and intrinsic viscosity of polymers in various brines even at high temperature (140° C) and at a controlled and low shear rate. It is thus possible to access to the rheological properties of dilute polymer solutions under conditions that, to our knowledge, cannot be performed by viscometers commercially available. The new technique involves a specific set up including a capillary and pressure transducers. It allows monitoring the effect of various chemical, mechanical, free radical and thermal modifications on the PAM structure after various ageing times. The performances of the technique were determined in terms of accuracy, and acquisition time. Various PAM compositions and different molar masses (104-106 g/mol) were used for calibration purposes. The technique was then applied to investigate the behavior of two industrial PAM (M>106g/mol) used in EOR: A sodium acrylamido-Tertiary-butyl sulfonate (ATBS) based PAM (SPAM), and a PAM terpolymer with ATBS, and N-vinylpyrrolidone (NVP) (PAM called SAV). Rheological properties and intrinsic viscosities were determined at low shear rates 8 to 800 s-1, at 25, 85 and 140°C, and for different salinities (20,000 to 240,000 TDS). In addition, the mechanical stability was evaluated by injection of a polymer solution in a capillary with a low internal diameter (125μm), and with a shear rate up to 1,500,000s-1. The results obtained using the new technique provide an efficient and reliable way of selecting the proper PAM chemistry for a given reservoir condition. Ultimately, it defines the salinity, temperature and shear rate domains where the PAM, SPAM or SAV are stable. The technique can be automated, is made of transportable devices, can be used in anaerobic conditions and provides a fast way of following changes in the rheological property of very high Mw industrial PAM over time. Copyright 2016, Society of Petroleum Engineers.