Three-dimensional Polymerization Research Articles

Comprehensive Characterization of Drying Oil Oxidation and Polymerization Using Time-Resolved Infrared Spectroscopy.

Drying oils like linseed oil are composed of multifunctional triglyceride molecules that can cure through three-dimensional free-radical polymerization into complex polymer networks. In the context of oil paint conservation, it is important to understand how factors like paint composition and curing conditions affect the chemistry and network structure of the oil polymer network and subsequently the links between the structure and long-term paint stability. Here, we employed time-resolved ATR-FTIR spectroscopy and comprehensive data analysis to study the curing behavior of five types of drying oil and the effects of curing temperature as well as the presence of a curing catalyst (PbO). Extracted concentration curves of key reactive functional groups point to a phase transition similar to a gel point that is especially pronounced in the presence of PbO, after which curing reactivity slows down dramatically. Analysis of kinetic parameters suggests that PbO induces a network structure with a more heterogeneous cross-link density, and the ATR-FTIR spectra indicate lower levels of oxidation in those cases. Finally, lower temperatures appear to favor the formation of carboxylic acid groups in oil mixtures with PbO.

On the Absence of Cyclic Structures in Branched Polystyrenes Synthesized by Living Three-Dimensional Radical Polymerization in the Medium of a Deteriorating Thermodynamic Quality Solvent

On the Absence of Cyclic Structures in Branched Polystyrenes Synthesized by Living Three-Dimensional Radical Polymerization in the Medium of a Deteriorating Thermodynamic Quality Solvent

On the Absence of Cyclic Structures in Branched Polystyrenes Synthesized by Living Three-Dimensional Radical Polymerization in the Medium of a Deteriorating Thermodynamic Quality Solvent

Branched polystyrenes are synthesized by the radical copolymerization of styrene and divinylbenzene with reversible inhibition (in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl) under deteriorating thermodynamic quality of the solvent. The resulting polymers are studied by size-exclusion chromatography combined with static light scattering, ozonolysis, NMR spectroscopy, and differential scanning calorimetry. The branched polymers synthesized by living radical polymerization are characterized by lower intrinsic viscosity values than their linear analogs. Kuhn–Mark–Houwink parameters for these polymers in a tetrahydrofuran solution (а = 0.29) confirm the nonlinear architecture of macromolecules and a high content of pendant double bonds comparable in the order of magnitude with their theoretical content in the absence of the cyclization reaction indicate their branched structure. The glass transition temperature of the branched polystyrenes is 20–35°С lower than the glass transition temperature of the linear polystyrene.

Wetting-Enabled Three-Dimensional Interfacial Polymerization (WET-DIP) for Bioinspired Anti-Dehydration Hydrogels.

Anti-dehydration hydrogels have attracted considerable attention due to their promising applications in stretchable sensors, flexible electronics, and soft robots. However, anti-dehydration hydrogels prepared by conventional strategies inevitably depend on additional chemicals or suffer from cumbersome preparation processes. Here, inspired by the succulent Fenestraria aurantiaca a one-step wetting-enabled three-dimensional interfacial polymerization (WET-DIP) strategy for constructing organogel-sealed anti-dehydration hydrogels is developed. By virtue of the preferential wetting on the hydrophobic-oleophilic substrate surfaces, the organogel precursor solution can spread on the three-dimensional (3D) surface and encapsulate the hydrogel precursor solution, forming anti-dehydration hydrogel with 3D shape after in situ interfacial polymerization. The WET-DIP strategy is simple and ingenious, and accessible to discretionary 3D-shaped anti-dehydration hydrogels with a controllable thickness of the organogel outer layer. Strain sensors based on this anti-dehydration hydrogel also exhibit long-term stability in signal monitoring. This WET-DIP strategy shows great potentialities for constructing hydrogel-based devices with long-term stability.

The effect of C60 fullerene polymerization processes on the mechanical properties of clusters forming ultrahard structures of 3D C60 polymers

We observed the effect of high (up to 80 GPa) pressure, catalyst (CS2) and laser irradiation on the process of three-dimensional (3D) polymerization of fullerene C60 and the mechanical properties of the 3D C60 samples. The studies were carried out using resonant Raman spectroscopy and piezospectroscopy, high resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy. We have revealed that the 3D C60 structure consists of at least two types of clusters formed by covalent bonds with a different set of force constants, while C60 molecules, as one of the elements of the 3D C60 structure (clusters), are preserved at least up to a pressure of 80 GPa. The intensity of Raman scattering depends on the wavelength of the exciting radiation (resonance effect) and a set of force constants: the higher their values, the shorter-wavelength exiting radiation is required for Raman scattering observation by such clusters. Clusters with bulk moduli from 454 GPa to 644 GPa are formed depending on methods of C60 polymerization. According to the set of clusters, 3D C60 samples with bulk moduli from 506 GPa to 608 GPa were obtained.

Computer simulation of block polymerization of 1,6-Hexanediol Diacrylate

In this paper, a computer model of the block three-dimensional free-radical polymerization of 1,6-Hexanediol Diacrylate (HDDA) is proposed. The model of the reaction system is based on an ideal mixing reactor. The reaction process is modeled by the Monte Carlo method. Accounting for the diffusion inhibition of the reaction is described using the free volume model. An adequate description of the experimental data of the calculated conversion rate curve is obtained. The nature of the change in the rate constant of the growth reaction with increasing conversion is shown.

Synthesis, characterization, and mercury removal application of surface modified kapok fibers with dopamine (DA): investigation of bidentate adsorption

The present work evaluated a mercury adsorption from its aqueous solution through chemically enhanced kapok fiber with the self-polymerization of the dopamine (DA) on the surface of the kapok fiber. The adsorption capacity of mercury ions was greatly improved with the DA coated kapok fiber (235.7 mg/g), compared with the raw kapok fiber (39.9 mg/g). The kinetic and isotherm studies were established, and the most fitting pseudo-first-order reaction and the Langmuir model indicated that the homogenous chemisorption occurred on the surface of the chemically modified kapok fiber with the equilibrium time of 80 min. According to the FTIR and XPS spectra analyses, the bidentate adsorption of mercury ions was illustrated with hydroxyl groups induced by three-dimensional (3-D) polymerization of DA. The optimum pH was at 8 for the adsorption with the dopamine-coated kapok fiber and the high adsorption efficiency was still maintained after three recycle times, extending its application to treating a number of industrial wastewater streams.

Reversible Membrane Tethering by ZipA Determines FtsZ Polymerization in Two and Three Dimensions.

In most bacteria, the early step of septum formation implies the association of soluble FtsZ polymers with the cytoplasmic membrane. ZipA, together with FtsA, provides membrane tethering to FtsZ in Escherichia coli, forming a dynamic proto-ring that serves as an assembly scaffold for the remaining elements of the divisome. Despite their importance for bacterial cell division, multivalent interactions between proto-ring elements at membrane surfaces remain poorly characterized in quantitative terms. We measured the binding of FtsZ to ZipA incorporated in supported lipid bilayers at controlled densities by using a combination of biophysical surface-sensitive techniques (quartz crystal microbalance and spectroscopic ellipsometry) and analyzed how ZipA density and FtsZ concentration control the state of assembly of FtsZ. We found that ZipA attachment enables FtsZ-GMPCPP (where GMPCPP is a GTP analogue with a reduced level of hydrolysis) to assemble in several distinct ways: (i) two-dimensional polymerization at the membrane and (ii) three-dimensional polymerization from the membrane into the solution phase where this may be associated with the formation of higher-order complexes. In these processes, ZipA is required to enrich FtsZ at the surface but the FtsZ bulk concentration defines which morphology is being formed. Moreover, we report a strong effect of the nucleotide (GDP vs GMPCPP/GTP) on the kinetics of ZipA association/dissociation of FtsZ. These results provide insights into the mode of interaction of proto-ring elements in minimal membrane systems and contribute to the completion of our understanding of the initial events of bacterial division.

New Kinetic Model of Polyaddition of Asymmetric <i>ABВ/</i> Monomer in the Presence of Trifunctional Core with Substitution Effect

Three-dimensional step polymerization of ABB/ and В3 monomers (ABB/+В3) was described using the new structural-kinetic model. Polymerization process was simulated with the variation of reactivity of B groups in the ABB/ and B3 monomers during the process (substitution effect). Polymerization simulation with substitution effect represents the most general case of three-dimensional step polymerization ABB/+В3.

Three-dimensional supramolecular polymerization based on pillar[n]arenes (n = 5, 6) and halogen bonding interactions.

Herein we demonstrate that three dimensional supramolecular polymerization networks were constructed both in solution and in the solid state by the combination of pillar[5,6]arene-based host-guest complexes and 1,4-diiodotetrafluorobenzene involving halogen bonding systems.

Моделирование методом Монте-Карло трехмерной свободно-радикальной полимеризации тетрафункциональных мономеров [На англ.

Моделирование методом Монте-Карло трехмерной свободно-радикальной полимеризации тетрафункциональных мономеров [На англ.

Thermodynamic properties of three-dimensional radical polymerization of dimethacrylates and their relation to the structure and properties of network polymers

For the polymerization of dimethacrylates, thermodynamic properties related to effect of the formed network polymer on the reaction between pendant methacrylate groups and free radicals have been studied. The polymer matrix creates steric hindrances for this reaction and impedes the shrinkage process accompanying the opening of С=С bonds. As a result, internal stresses develop in the polymer, the heat of polymerization of methacrylate groups decreases compared with the polymerization of methyl methacrylate, and the full conversion of double bonds is prevented. The relaxation of internal stresses and of excess free volume leads to the spontaneous cracking of network polymers and causes formation of regular adhesive-shrinkage patterns. The process of superslow relaxation of internal stresses in polymer films has been ascertained, and the mechanochemical model of this process has been advanced. The effect of internal stresses on the physicomechanical properties of polydimethacrylates has been discussed.

Aqueous Antibacterial Enhancement Using Kapok Fibers Chemically Modified in 3-D Crosslinked Structure.

The surface of a kapok fiber was coated with Dopamine (DOPA) through a three-dimensional (3-D) polymerization. Such surface-modified kapok fiber was useful in deactivating microbial activity of microorganisms such as bacteria. The morphology of the surface-modified kapok fiber was analyzed with a field emission scanning electron microscope (FE-SEM). After a silver coating process along with DOPA functionalization, a strong antibacterial property was observed against Escherichia coli (E. coli), using a direct contact method. Almost 100% of bacterial cells were deactivated in 4 h, also showing a complete hindrance to a bacterial growth for 48 h. With the help of the images of FE-SEM and its analysis, the mechanism of an antibacterial assay was enlightened and reasonably estimated that silver ions from the poly-DOPA-coated kapok fiber with silver (KF-DOPA/Ag) led to alterations of cell morphology. This 3-D composite successfully interacted in vitro with functional groups in terms of bacterial deactivation.

Influence of the size of the cubic lattice and the activity of its walls on the kinetics of the formation of a unitary three-dimensional structural element

The results of Monte Carlo simulations of the kinetics of the three-dimensional free-radical polymerization of tetrafunctional monomers (TFM) in terms of the formation of a unitary three-dimensional structural element (UTSE) are presented. The process is simulation on 103 → 503-sized cubic lattices with walls of different activity with respect to free radicals. Changes in the degree of UTSE polymerization, number of crosslinks and cycles, mechanisms of chains crosslinking and cyclization and other parameters caused by changes of the conditions of three-dimensional free-radical polymerization of TFM, as well as the difference between the effects of active and inert walls, are reported.

Structural characterization of heavy metal SiO2–Bi2O3 glasses and glass–ceramics

29Si MAS NMR spectroscopic data obtained for heavy metal SiO2–Bi2O3 glasses and partially crystallized samples of similar composition were used to investigate the changes induced in their local structure as the ratio between Bi3+ and Si4+ cations decreases from 18:1 to 6:7. Progressive increase of SiO2/Bi2O3 ratio contributes to the structural relaxation of vitreous network and enhances the glass stability. In glass samples with high silica content the increasing number of Si–O–Si bridges proves the three-dimensional polymerization of silicate network. The shape of NMR signals for glass–ceramic samples depends on the crystalline phases formed for different SiO2/Bi2O3 ratios. The crystalline phases developed by heat treatment of vitreous matrices were identified by X-ray diffraction as Bi12SiO20, Bi5.6Si0.5O9.4 and Bi2SiO5. Scanning electron microscopy analysis was used to examine the morphology of the crystals developed in the glassy silica rich matrices.

ChemInform Abstract: Modeling Free Radical Polymerization Using Dissipative Particle Dynamics

AbstractReview: 46 refs.

Studies on N-vinylformamide cross-linked copolymers

Copolymers of N-vinylformamide (NVF) cross-linked with three multifunctional monomers, including divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDMA), and N,N′-methylenebisacrylamide (MBA) were synthetized by a three-dimensional free radical polymerization in inverse suspension using 2,2′-azobis(2-methylpropionamide) dihydrochloride (AIBA) as an initiator. Methyl silicon oil was used as the continuous phase during the polymerization processes. Fourier-transform adsorption infrared (FT-IR) spectra revealed the presence of silicone oil traces and suggested that silicone oil strongly interacted with the copolymers surface. Purification procedure allowed to completely remove the silicon oil traces from P(NVF-co-DVB) only. The morphology and the structure of the investigated copolymers were examined by optical microscopy, FT-IR, and FT-Raman (Fourier-transform Raman spectroscopy) methods.

Reversible deactivation radical polymerization of polyfunctional monomers

In this review, the results of modern theoretical and experimental investigations of three-dimensional reversible-deactivation radical polymerization are discussed. The most important factors affecting the critical gelation conversion, the probability of cyclization, and the topological structures of polymers are underlined. Examples of the most promising application of the reversible deactivation radical polymerization to produce new polymer materials are given.

Synthesis of Clay Composites of Polyacrylamide and Poly-2-Hydroxyethylacrylate and Sorbtion Ability in the Case of Cetylpyridinium Bromide

<p>By the three-dimensional polymerization of nonionic (polyhydroxyethylacrylate and polyacrylamide) <br />polymers and bentonite clay from Manyrak deposit (East Kazakhstan Region) and with using of process <br />preliminary intercalation of monomers in an aqueous suspension of bentonite (polymerization in situ) the <br />chemically crosslinked composite gels were synthesized. Optimal conditions of synthesis and physical-chemical properties of composition gels were established. It was shown, that yield of gel fraction increases <br />with increasing contents of bentonite clay. Insignificant adding of negative charged particles of bentonite clay <br />gives to polymer gels of nonionic type polyelectrolyte character, that comes out in decreasing of swelling <br />degree of gels under effect of ionic strength. By using physical and chemical methods of research: equilibrium <br />swelling, IR spectroscopy, scanning electron microscope (SEM), sorption-desorption, etc. were shown the <br />formation of compatible, homogeneous, swelling in water polyelectrolyte gels formed via hydrogen bonds <br />between the components of the gel, stabilized by hydrophobic interactions of the organic polymer chains. <br />The possibility of the regulation of swelling ability of the composite gels through varying of the outside and <br />inside factors as: consist of the composition, conditions of intercalation, pH of the environment, temperature <br />and ionic strength was established, that is stimulus sensitivity of gels. The sorbtion capacity of polymer-clay composites in attitude surface active substance cetylpyridinium bromide were estimated. Increasing of <br />temperature of environment and content of bentonite clay in composite promotes the process of sorbtion <br />of surface-active substances. Considerably high sorption capacity of polymer clay composition based on <br />more hydrophilic polymer – polyacrylamide was established. By the results of investigations one may, that <br />synthesized polymer clay composites after suitable investigations can be recommend as sorbents of cationic <br />surface active substances.</p>

Modeling free radical polymerization using dissipative particle dynamics

Understanding the details of free radical polymerization (FRP) in multi-component mixtures and solutions is of great importance for the synthesis of polymeric functional materials. Using the framework of dissipative particle dynamics (DPD), we develop a new computational approach to model FRP that couples the reaction kinetics for the polymerization processes to the dynamics of the complex fluid. We specifically consider two mechanisms of chain termination: disproportionation and combination. We analyze the effects of initiation, propagation, and termination on the polymerization kinetics in three-dimensional bulk polymerization by varying the corresponding reaction probabilities. Our model not only allows us to capture the interplay between hydrodynamics and reaction kinetics, but also provides an effective means to model polymerization in the presence of solid inclusions. We demonstrate the latter feature by simulating the formation of polymer-clay nanocomposite gels by FRP in solution in the absence of organic cross-linking agents, where the exfoliated clay particles serve as multi-functional cross-linkers for the polymer network. We observe that increasing the volume fraction of clay particles can lead to an increase in the number of inter-particle cross-linking chains, which could improve the mechanical properties of the material. Our findings provide insight into the polymerization kinetics of the FRP, as well as potential guidelines for tailoring experimental conditions to achieve the desired polymerization products.