Process Of Polymer Formation Research Articles

Analysis of the results of field tests of viscoelastic compositions under the conditions of a complex terrigenous reservoir in the Caspian sea

The publication analyzes the use of viscoelastic systems in order to increase the efficiency of oil production in the Caspian fields. The conducted studies of the results of pilot field work on the introduction of polymer flooding technologies in complexly constructed terrigenous reservoirs have shown a number of disadvantages of the systems used at the pilot site. In particular, the premature destruction of the polymer compositions used and the subsequent sharp watering of the extracted products were revealed. The research covers technology tests from November 2014 to October 2021, the results of which established the presence of deteriorating dynamics in the removal of polymer material, in addition, the study revealed a high influence of thermobaric and reservoir conditions on the polymer formation process and its subsequent properties. The classic solution to the described problem is the use of compositions with higher viscosity indices, however, laboratory experiments with the use of reservoir fluid have shown a decrease in the characteristics of the compositions used while maintaining conditions close to reservoir conditions. Based on the results of the research, an approach based on a systematic solution of the problem was proposed, the existing line of agents was modernized taking into account experimental data with the reaction of compositions to reservoir fluids, including elements of control and regulation of the oil recovery process during exposure, changes in the volumes of injected polymer solutions. Keywords: water intrusion; systemic approach; viscoelastic systems; oil recovery.

Hydrothermal Generation of Conjugated Polymers Using the Example of Pyrrone Polymers and Polybenzimidazoles.

Various polyimides and polyamides have recently been prepared via hydrothermal synthesis in nothing but H2O under high‐pressure and high‐temperature conditions. However, none of the prepared polymers feature a truly conjugated polymer backbone. Here, we report on an expansion of the synthetic scope of this straightforward and inherently environmentally friendly polymerization technique to the generation of conjugated polymers. Selected representatives of two different polymer classes, pyrrone polymers and polybenzimidazoles, were generated hydrothermally. We present a mechanistic discussion of the polymer formation process as well as an electrochemical characterization of the most promising product.

Internal structure study of polyurethane-polyurea by nuclear magnetic resonance method

We study the effect of chemical composition, solubility parameter of the segments and their length on the size of the domains, interphase thickness of the interfacial layer and the degree of phase separation in polyurethane-polyurea synthesized from oligomeric diisocyanate, cuamine M and polyols based on polyethylene oxide, polypropylene oxide and polybutadiene. The measurements were performed by a variety of techniques with specific pulse sequence such as proton spin-diffusion solid-state nuclear magnetic resonance spectroscopy, nuclear magnetic resonance spectroscopy with cross-polarization. The measurements were carried out on Bruker Avance II 500 operating at proton frequency equal to 500.13 MHz. It was found that the properties of segmented polyurethane-polyurea depend directly on the degree of phase separation between the hard segments and the mobile matrix. The study of the transverse relaxation time of the samples showed that the molecular mobility in polyurethane is represented by four components. Understanding of the polymer formation process, components distribution by volume, and knowledge about predisposition to form certain connections can be used for creation of polymeric materials with the required characteristics important for the industry

Synthesis and Properties of Adhesive Polymer-Methylmethacrylate Materials

Kinetics of emulsion polymerization of hydrophilic vinyl monomers in the presence of polyvinylpyrrolidone and technological principles of their synthesis are determined. Reasonable technological parameters in the synthesis of copolymers are determined. Physicochemical properties of the synthesized copolymers (surface tension, the size of latex particles, and pH) are determined. Synthesized graft copolymers were used to create high-adhesion polymer-monomer compositions. These compositions have high reactivity at room temperature. It can be regulated by the nature of the polymer matrix and the introduction of comonomers and fillers due to the influence of physicochemical factors on the process of polymer formation. The rate of polymerization and the degree of monomer conversion largely depend on the nature of the polymer matrix. The highest polymerization rate and the maximum degree of conversion are observed when using a copolymer of polyvinylpyrrolidone and polymethylmethacrylate. Materials based on the developed compositions are characterized by a low residual monomer content and high operational properties, such as surface hardness, Vicat softening temperature, and adhesive bond strength to supports of different nature.

PERBANDINGAN JARAK PENYINARAN DAN KETEBALAN BAHAN TERHADAP KEKERASAN PERMUKAAN RESIN KOMPOSIT TIPE BULK FILL

Background: The polymerisation process is a process of polymer formation of a combination of several monomers. This is due to the incomplete polymerization, which affects the consistency and durability of the composite resin in the oral cavity. The maximum surface can result in composite resin are not able to withstand the pressure generated during mastication it can undergo cracking (rupture) or off the tooth. Purpose: To compare the material thickness and curing light distance of bulk-fill composite resin to determine its’ surface consistency. Method: Laboratorium experimental study with a post-test only with control group design. A total of 63 composite resin pieces were used as samples and divided into 9 treatment groups with different curing light distance (0 mm, 2 mm, 5 mm) and thickness (2 mm, 4 mm, 6 mm). Data were analyzed with One-Way ANOVA with a significance value of 0,000 (p<0,05). Post-Hoc Tuckey analysis with a p(<0,05) was used to determine the difference between two groups. Result: Post Hoc Tuckey analysis resulted in a significant value (p<0,05), which shows that there is a significant difference between each group and in the result show group with the thickness 2 mm and light distance 0 mm was the highest score. Conclusion: There is a comparison between curing light distance and material thickness towards surface consistency of Bulk Fill Composite Resin with thickness 2 mm and 4 mm with curing light distance 0 mm and 2 mm.

Robust Numerical Resolution of Nakamura Crystallization Kinetics

The numerical prediction of crystallization transformation is of great interest in several applications. One such application is the polymer-forming process. In this short communication, the integration of the widely used Nakamura kinetics is discussed. A robust time integration method is proposed. In order to overcome its singularities, the Nakamura function is thresholded. A convergence analysis provides guidelines for the threshold values and time discretization.

Behavior of lysozyme adsorbed onto biological liquid crystal lipid monolayer at the air/water interface**Project supported by the National Natural Science Foundation of China (Grant Nos. 21402114 and 11544009), the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2016JM2010), the Fundamental Research Funds for the Central Universities of China (Grant No. GK201603026), and the National University Science

The interaction between proteins and lipids is one of the basic problems of modern biochemistry and biophysics. The purpose of this study is to compare the penetration degree of lysozyme into 1,2-diapalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethano-lamine (DPPE) by analyzing the data of surface pressure–area (π–A) isotherms and surface pressure–time (π–T) curves. Lysozyme can penetrate into both DPPC and DPPE monolayers because of the increase of surface pressure at an initial pressure of 15 mN/m. However, the changes of DPPE are larger than DPPC, indicating stronger interaction of lysozyme with DPPE than DPPC. The reason may be due to the different head groups and phase state of DPPC and DPPE monolayers at the surface pressure of 15 mN/m. Atomic force microscopy reveals that lysozyme was absorbed by DPPC and DPPE monolayers, which leads to self-aggregation and self-assembly, forming irregular multimers and conical multimeric. Through analysis, we think that the process of polymer formation is similar to the aggregation mechanism of amyloid fibers.

In‐process thermochemical analysis of in situ poly(ethylene glycol methacrylate‐co‐glycidyl methacrylate) monolithic adsorbent synthesis

ABSTRACTThermomolecular mechanisms associated with the synthesis of polymethacrylate monoliths are critical in controlling the physicochemical and binding characteristics of the adsorbent. Notwithstanding, there has been limited reported work on probing the underlining synthesis mechanism essential in establishing the relationship between in‐process polymerization characteristics and the physicochemical properties of the monolith for tailored applications. In this article, we present a real‐time thermochemical analysis of polymethacrylate monolith synthesis by free‐radical polymerization to probe the effects on the physicochemical characteristics of the adsorbent. The experimental results show that an increase in the crosslinker monomer concentration from 30 to 70% resulted in a peak temperature increase from 96.3 to 114.3 °C. Also, an increase in the initiator (benzoyl peroxide) concentration from 1 to 3% w/v resulted in a temperature increase from 90.7 to 106.3 °C. A temperature buildup increases the kinetic rate of intermolecular collision associated with microglobular formation and interglobular interactions. This reduces the structural homogeneity and macroporosity of the polymer matrix. A two‐phase reactive crystallization model was used to characterize the rate of monomeric reaction after initiation and microglobular formation from the liquid monomeric phase to formulate the theoretical framework essential for evaluating the kinetics of the polymer formation process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43507.

POLYMER SYNTHESIS ON COMMAND

RESEARCHERS AT CARNEGIE Mellon University (CMU) have brought a new level of control to atom transfer radical polymerization (ATRP), a reaction that is used to make specialty polymers for products such as adhesives and coatings. By applying specific voltages to an electrochemical cell filled with a solution of catalyst, monomer, and alkyl halide, the scientists are able to turn the polymer formation process on and off at will. The work, described last week at the ACS national meeting in Anaheim, Calif., and published in Science (DOI: 10.1126/science.1202357), relies on a type of reaction in which a transition-metal catalyst is used to form carboncarbon bonds. The addition of electrochemistry to ATRP “enables further polymerization control” than was previously possible, CMU chemist Krzysztof Matyjaszewski said at the meeting. His group developed the new approach, which could lead to the more precise synthesis of polymers of greater complexity. The inherent rate of ATRP is controlled by a redox ...

Self-Controlled Synthesis of Hyperbranched Poly(ether ketone)s from A3 + B2 Approach via Different Solubilities of Monomers in the Reaction Medium

Hyperbranched poly(ether ketone)s (PEK's) were synthesized via A3 + B2 polymerization approach without forming cross-linked products, because the polymer-forming process based on Friedel−Crafts reaction was kinetically controlled by the solubility difference of monomers in the viscous hydrophilic reaction medium, poly(phosphoric acid) (PPA)/phosphorus pentoxide (P2O5). The hydrophilic trimesic acid as an A3 monomer is soluble in the reaction medium, while hydrophobic diphenyl ether and 1,4-diphenoxybenzene as B2 monomers are marginally soluble. It is hypothesized that the gelation was avoided because of the following two factors: (i) self-regulated feeding of the arylether monomers into the system driven by their poor solubility and phase separation from PPA/P2O5 medium; (ii) reaction-medium-induced isolation of growing macromolecules promoted by the high bulk viscosity. Both polymerization experiments based on equimolar or equifunctional stoichiometry (A3:B2) resulted in completely soluble hyperbranched...

Electrochemically formed two-component films comprised of fullerene and transition-metal components

Abstract This paper reviews the results of investigations into the electrochemical formation and properties of redox-active films formed from fullerenes and selected transition-metal complexes. These polymeric films are formed on the electrode surface during electroreduction of a solution containing a fullerene or a fullerene derivative and complexes of Pd(II), Pt(II), Rh(II) and Ir(I). The polymeric network is formed through covalent bonding between the transition-metal atoms (or complexes) and the fullerenes. Films containing C60 exhibit electrochemical activity in the negative potential range due to the reduction of the fullerene component. In this potential range, a decrease in the film resistance is also observed. In the case of the well-studied C60/Pt and C60/Pd films, the polymer formation process may also be accompanied by deposition of metal nanocrystals if a high ratio of metal complex to fullerene is used during film formation. The presence of this metallic phase in the film influences its morphology, structure, and electrochemical properties. Films formed from C60 with covalently bound electron-donating groups exhibit electrochemical activity in both negative and positive potential ranges. Since these systems exhibit both p- and n-doping properties, they can be called ‘double cables’. These fullerene/transition-metal films may have considerable potential for a number of applications. They can be used as charge storage materials for batteries and photovoltaic devices. The C60/Pd film can be also used as an electrochemical sensor. Films of C60/Pd and C60/Pt containing metallic palladium or platinum particles catalyze hydrogenation of olefins and acetylenes. Laser ablation of electrochemically formed C60/M and C70/M films (M = Pt or Ir) results in the fragmentation and formation of hetero-fullerenes such us [C59M]+ and [C58M]–. To cite this article: K. Winkler and A.L. Balch, C. R. Chimie 9 (2006).

Nucleation kinetics of polymer formation on nucleation agent

The initial stadium of crystallization of polymers (nucleation process) on a nucleation agent is studied within the standard nucleation model. A nucleation agent is added to the melt to increase the nucleation rate. It is supposed that nucleation agent forms nucleation centers, or active centers, on which the formation of crystalline polymer starts. The basic kinetic equations describing such a process are solved numerically to determine the basic characteristics of nucleation process—the number density of nuclei, nucleation rate and the total number of nuclei as a function of time. The results of numerical computation are in good agreement with the experimental data obtained by small angle X-ray scattering (SAXS) method for polyethylene. The rate of formation of nuclei of various sizes reaches the same limit at long times. This limit is lower than the corresponding stationary nucleation rate due to exhaustion of active centers during polymer formation process, which was taken into account.

A Kinetic Mechanism for the Polymerization of α1-Antitrypsin

The mutation in the Z deficiency variant of alpha1-antitrypsin perturbs the structure of the protein to allow a unique intermolecular linkage. These loop-sheet polymers are retained within the endoplasmic reticulum of hepatocytes to form inclusions that are associated with neonatal hepatitis, juvenile cirrhosis, and hepatocellular carcinoma. The process of polymer formation has been investigated here by intrinsic tryptophan fluorescence, fluorescence polarization, circular dichroic spectra and extrinsic fluorescence with 8-anilino-1-naphthalenesulfonic acid and tetramethylrhodamine-5-iodoacetamide. These biophysical techniques have demonstrated that alpha1-antitrypsin polymerization is a two-stage process and have allowed the calculation of rates for both of these steps. The initial fast phase is unimolecular and likely to represent temperature-induced protein unfolding, while the slow phase is bimolecular and associated with loop-sheet interaction and polymer formation. The naturally occurring Z, S, and I variants and recombinant site-directed reactive loop and shutter domain mutants of alpha1-antitrypsin were used to demonstrate the close association between protein stability and rate of alpha1-antitrypsin polymerization. Taken together, these data allow us to propose a kinetic mechanism for alpha1-antitrypsin polymer formation that involves the generation of an unstable intermediate, which can form polymers or generate latent protein.

Organosilicon Polymers?Synthesis, Architecture, Reactivity and Applications

Tailoring of polysilanes with given architectures and reactivities is a great challenge in the field of SiC pre-ceramic polymers. This paper reviews recent polysilane and related copolymer synthesis reactions. It is shown that the Wurtz-type polymerization of dichloro-, trichloro- or tetrachloro-silanes, so far the most extensively studied, enables access to a large variety of architectures ranging from one- to three-dimensional (3D) topologies, and based on secondary >SiR2, tertiary RSi(Si)3 or quaternary Si(Si)4 silicon units in the polymer backbone. These polysilanes usually present an intrinsic low reactivity, detrimental for fiber processing. Examples are given to illustrate how this reactivity can be increased by secondary substitution reactions, which create reactive entities that can favor further crosslinking reactions. Secondly a novel route involving heterogeneously catalyzed disproportionation of chloromethyldisilanes, developed in our laboratory, is reviewed which offers a direct access to polysilyne-type 3D architecture constituted by arrangements of fused rings. The Lewis-base catalyzed disproportionation mechanism is discussed and seems to involve donor-stabilized silylenes as key intermediates in the polymer formation process. The experimental results are supported by ab-initio quantum chemical calculations. Silylenes attack the Si sites of higher functionality causing a high regioselectivity for the exclusive formation of branched oligosilanes. The oligomers undergo thermally induced branching and crosslinking reactions leading to poly(chloromethylsilane)s. Obviously, there are analogies to the oligomer and polymer formation of the transition-metal complex catalyzed dehydropolymerzation of methyldisilanes. Poly(chloromethylsilane)s exhibit a high reactivity due to the presence of Si–Cl bonds. Disproportionation of chloromethyldisilanes in presence of olefins such as styrene provides promising polymer precursors for SiC fibers. Their rheological properties have been investigated for various styrene contents. The polymer fibers spun from melt are cured under ammonia, and then pyrolyzed to silicon carbide fibers, showing temperature resistance up to 1500 °C. © 1996 by John Wiley & Sons, Ltd.

The effect of caldesmon on assembly and dynamic properties of actin

Our earlier fluorescence measurements using N-(1-pyrenyl)iodoacetamide-labeled actin revealed that caldesmon interacts with G-actin accelerating its nucleation at low salt concentration and causing polymerization in the absence of sale [Gałazkiewicz, B., Mossakowska, M., Osińska, H. & Dabrowska, R. (1985) FEBS Lett. 184, 144-149]. In this work the caldesmon-induced process of actin polymerization as well as the dynamic properties of the polymers formed have been investigated with the use of fluorescence, electron paramagnetic resonance (EPR) and electron microscopy techniques. Fluorescence titration of N-(1-pyrenyl)iodoacetamide-labeled actin with caldesmon showed saturation of the polymerization at a 1:3 molar ratio of caldesmon/actin monomer. Parallel pelleting experiments revealed, however, that the process of polymer formation is biphasic and only at higher concentrations of caldesmon does the copolymer contain around one caldesmon/three actin monomers. At low concentration of caldesmon a complex of one caldesmon/nine actin monomers is formed. EPR spectroscopy, using maleimide spin label bound at Cys374 of actin, also indicated that one caldesmon molecule polymerizes nine actin monomers. Taken together, these results might suggest the existence of weak and strong forms of actin binding to caldesmon and detection of only the latter by the fluorescence method. Copolymers of actin and caldesmon are indistinguishable from actin polymerized by salt with respect to their appearance in the electron microscope and their ability to interact with heavy meromyosin, although they are characterized by lower torsional flexibility as indicated by immobilization of spin labels attached to actin.

Laser‐induced polymerization of functional derivatives of acetylene

AbstractPhotochemical and photophysical processes leading to the formation of polymers with a conjugated double bond system under He‐Cd laser irradiation have been considered. Phenyl‐ and diphenylpropargylamines are utilized as monomers. The polymerization of these monomers is carried out only in the presence of an electron acceptor such as tetrabromomethane. The polymer formation process is directed to obtaining an intermediate compound followed by its polymerization. The polymerization of intermediate compound is carried out by cationic reaction of triple bond in the presence of electron acceptor. The polymer structure and properties have been investigated. The parameters of lightsensitive layers based on diphenylpropargylamine have been determined.

Laser induced polymerization of acetylene derivatives

He-Cd laser induced polymerization of aryl-propargylamines such as phenyl- and diphenylpropargylamines were studied. The polymerization of these monomers was shown to be realized only in presence of acceptor of electrons. Polymer formation process is based on the formation of an intermediate compound and its following polymerization by the radical reaction of C≡C bond. Photochemical and photophysical processes leading to the formation of intermediate compound were investigated. The polymers obtained were characterized by IR-, ESR-, NMR-spectroscopy. The conjugated double bond system formation is the main characteristic of these polymers. Some polymer properties were studied.

Preparation of quaternary nitrogen-containing plasma films and their application to moisture sensors

To seek the possible formation of positively charged plasma films the chemical composition of plasma films formed from organosilicones containing nitrogen (hexamethyldisilazane (HMDSZ), trimethylsilyldimethylamine (TMSDMA) and a mixture of tetramethylsilane and NH 3) was analysed by elemental analysis and IR spectroscopy, and quaternization of these films with methyl bromide was carried out. IR spectroscopic and electron spectroscopy for chemical analysis studies revealed that the plasma films from TMSDMA and the TMS-NH 3 mixture were successfully quaternized but those from HMDSZ were not. This indicates that the structural characteristics of the starting compounds exert a powerful influence on the polymer-forming process. The quaternized plasma films prepared from TMSDMA were used to prepare moisture sensor devices.

Effects of functional groups in glow discharge polymerization

Glow discharge polymerizations of allyltrimethylsilane (ATMS) and trimethylvinyloxysilane (TMVOS) were investigated by elemental analysis and infrared spectroscopy. The formed polymers were far different in elemental composition from the starting materials, and possessed high carbon and hydrogen contents. There was less difference in an infrared-spectral sense between the two polymers from ATMS and TMVOS. A polymer-forming process in a discharge state is discussed.

Glow discharge polymerizations of tetrafluoroethylene, perfluoromethylcyclohexane and perfluorotoluene investigated by infrared spectroscopy and ESCA

Glow discharge polymerizations of tetrafluoroethylene, perfluoromethylcyclohexane and perfluorotoluene were investigated by infrared spectroscopy and ESCA to clarify the contribution of olefinic double bonds and cyclic structures. The products formed from the three compounds were deposited as filmy polymers containing large amount of fluorine. Their polymeric chains are composed of CF, CF-CFn, CF2 and CF3 groups and have less dependency on chemical structures of the starting compounds. The polymer-forming process involves not only chain reactions via addition reaction to double bonds and via ringopening reaction but also the rupture of C-F bonds and the rearrangement of the ruptured fluorine atoms.