Homogeneous Solution Polymerization Research Articles

Effect of inorganic particles on the rheological properties of nano-SiO2 grafted modified polymers

Polymer flooding technology has become the most widely utilized chemical flooding technology in the world. The polymer structure gradually grows from linear to branched and hyperbranched as reservoir variability increases and polymer flooding technology advances. In this study, the nano-SiO2 was first controllably modified, and subsequently, a series of nano-SiO2 grafted modified polymers (MNSP) were synthesized using homogeneous aqueous solution polymerization with modified nano-SiO2 and another functional monomer. The rheological properties of MNSP were analyzed by using the MCR 301 rheometer; then, the mechanism of the influence of the concentration and the modification degree of nano-SiO2 on the rheological properties of MNSP was explored from the microscopic standpoint. The results demonstrate that at a salinity of 3 × 104 mg/L and temperature of 85 °C, the viscosity of the MNSP polymer is superior to that of the standard amphiphilic polymer APC16 whose synthesized monomers do not include nano-SiO2. When the concentration and the modification degree of nano-SiO2 were increased, the solution viscosity first increased and then decreased, and this is mostly due to the addition of inorganic nanoparticles, which stimulates the creation of a three-dimensional network structure and improves the solution characteristics of MNSP. However, too much modified SiO2 addition will interfere with polymerization between various monomers. The modification degree of the nano-SiO2 mostly influences the density of the polymer-formed network structure, the active sites on the modified nano-SiO2 surface rise as the degree of modification increases, as does spatial site resistance, resulting in inferior polymer characteristics. The findings of the experiments reveal fresh ideas for inorganic particles compounding organic polymers and expand the use area of polymers in the oilfield.

(Invited) Hard Polymers: Irreversible Synthetic Routes to Ultra-Strong Two-Dimensional Polymers in Bulk

Polymers that extend covalently in two dimensions have attracted recent attention as a means of combining the mechanical strength and in-plane energy conduction of conventional two-dimensional (2D) materials with the low densities, synthetic processability, and organic composition of their one-dimensional counterparts. Efforts to date have proven successful in forms that do not allow full realization of these properties, such as polymerization at flat interfaces or fixation of monomers in immobilized lattices. A frequently employed synthetic approach is to introduce microscopic reversibility, at the cost of bond stability, to achieve 2D crystals after extensive error correction. Herein we demonstrate a synthetic route to 2D irreversible polycondensation directly in the solution phase, resulting in a covalently bonded 2D polymer that is chemically stable and highly processable. Further fabrication offers highly oriented, free-standing films which exhibit exceptional 2D elastic modulus and yield strength at 12.7 ± 3.8 GPa and 488 ± 57 MPa, respectively. The highly planar asymmetry of 2D molecules is evidenced by chemical atomic force microscopy, and molecular alignment in nanofilms is supported by a polarized photoluminescence centered at 580 and 680 nm from different dipole transitions. We have also made substantial progresses in the theory of 2D chain growth. We performed a chemical kinetic simulation study to understand 2D polymerization in homogeneous solution with irreversible chemical steps. We show that reaction sites for polymerization in 2D always scale unfavourably compared to 3D, growing as molecular weight to the 1/2 power versus 2/3 power for 3D. However, certain mechanisms can effectively suppress out-of-plane defect formation and subsequent 3D growth. We consider two such mechanisms, which we call bond-planarity and templated autocatalysis. In the first, although single bonds can easily rotate out-of-plane to render polymerization in 3D, some double-bond linkages prefer a planar configuration. In the second mechanism, stacked 2D plates may act as van der Waals templates for each other to enhance growth, which leads to an autocatalysis. When linkage reactions possess a 1000:1 selectivity (γ) for staying in plane versus rotating, solution-synthesized 2D polymers can have comparable size and yield with those synthesized from confined polymerization on a surface. Autocatalysis could achieve similar effects when self-templating accelerates 2D growth by a factor β of 106. A combined strategy relaxes the requirement of both mechanisms by over one order of magnitude. We map the dependence of molecular weight and yield for 2D polymer on the reaction parameters, allowing experimental results to be used to estimate β and γ. Our calculations show for the first time from theory, the feasibility of producing two-dimensional polymers from irreversible polymerization in solution. These new synthetic routes, now experimentally validated, provides exciting, new opportunities for 2D polymers in applications ranging from composite structures to barrier coating materials.

Activation of a Palladium-Based Catalyst by Hexafluoroisopropanol for Polyketone Synthesis via Homogeneous Solution Polymerization

Polyketone (PK) is a promising material because of its superior qualities as an engineering plastic and the direct use of CO. It is typically produced using slurry polymerization techniques, which cause reactor fouling and low bulk density product. Here, solution polymerization of CO/ethene/propene with high-molecular-weight products (240.3 kDa) and high catalytic activity (36.1 kg PK·g–1 Pd·h–1) was achieved utilizing a mixture of hexafluoroisopropanol (HFIP) and methanol. Both the activity and Mw are an order of magnitude higher than those reported in the literature. HFIP was able to activate the palladium-based precatalyst without using any strong acid. The 31P NMR, single-crystal X-ray diffraction, and density functional theory analysis prove that HFIP decreased the coordination between palladium and the acetate ligands of the precatalyst without the disassociation of the acetate. Furthermore, the active centers in the HFIP system were more stable than that in the catalytic system with strong acid.

Improving water resistance and mechanical properties of waterborne acrylic resin modified by 3,3′,5,5′-tetramethyl-4,4′-biphenyl diglycidyl ether

3,3′,5,5′-tetramethyl-4,4′-biphenyl diglycidyl ether (TMBPDGE) modified waterborne acrylic resin with excellent water resistance and mechanical properties was synthesized by a homogeneous solution polymerization. Infrared analysis revealed that TMBPDGE could successfully participate in the synthesis. On this basis, the experimental conditions such as polymerization method, solid content, monomer addition method and curing temperature are optimized by using the results of immersion test, contact angle, tensile strength, elongation at break and hardness determination. The optimal amount of TMBPDGE is investigated and the resin is further characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The experimental results show that when the amount of TMBPDGE is 10 wt%, the water resistance and mechanical properties of the resin are greatly enhanced, and the cured resin film modified by TMBPDGE can withstand the soaking in water for more than 35 days, while that of film without modification is only one day. The tensile strength can reach 9.12 MPa, which is 2.2 times than that of the film without modification. Based on the enhanced properties, the modified resin provides a great potential in the fields of wood coatings, which require good water resistance and mechanical properties.

A design framework for optimized economic and inherently safe operation conditions for isoperibolic semi-batch reactors

Thermal runaway in the semi-batch reactors (SBRs) involving exothermic reaction can have serious consequences and the primary driver of process design in the SBRs is economic performance. Hence, in this article, a general framework for safe-economic design and operation of isoperibolic SBRs via integrating advanced process optimization and inherently safe operation condition identification criteria is proposed, and is applied to homogeneous solution polymerization. First, a criterion is proposed to identify the thermally safe operation condition (QFS region, quick onset, fair conversion, and smooth temperature) of homogeneous solution polymerization and the comparison with the other common criteria is conducted. The adiabatic temperature diagrams are also extended to homogeneous solution polymerization considering avoiding triggering side or decomposition reactions under cooling failure. Furthermore, a large accumulation can occur due to the rapid decomposition of the initiator when the jacket temperature in the QFS region exceed a threshold value. Therefore, a new temperature diagram is introduced via combination initiator decomposition temperature and adiabatic temperature diagrams. Finally, the optimal safety-economic design of the simulation case is conducted. The process optimization algorithm is genetic algorithm and runaway criteria are the proposed criterion in this article and the target temperature criterion. The comparison between the target criterion and proposed criterion shows there are almost approximately identical conversion profiles and temperature profiles. This result proves the general proposed framework and further proves the validity of the proposed criterion. This general framework can be extended to other kinetic schemes and this work can contribute to the inherent safety design of semi-batch reactors.

A Surfactant for Enhanced Heavy Oil Recovery in Carbonate Reservoirs in High-Salinity and High-Temperature Conditions

In view of the difficulty of producing heavy oil from carbonate reservoirs, the surfactant SDY-1 was synthesized by homogeneous solution polymerization with a homogeneous solution polymerization technique using aliphatic amine polyoxyethylene ether (PAEn) H(OCH2CH2)nNR(CH2CH2O)nH as the raw material, epichlorohydrin as the reaction intermediate, tetrabutylammonium bromide and pentamethyldivinyltriamine as the promoters, and alkylphenol as the catalyst. Based on the analysis of reservoir fluid and rock properties, the performance of the surfactant SDY-1 was evaluated in terms of its heat resistance, its salinity tolerance, its ability to change the heavy oil–water interfacial tension and rock wettability and its oil washing efficiency. The results show that when the salinity of the formation water is 2.23 × 105 mg/L, the addition of surfactant SDY-1 can lower the super-heavy oil–water interfacial tension with an asphaltene concentration of 30.19 wt.%, which is aged at a temperature of 140 °C for 3 days, from 22.41 to 0.366 mN/m. In addition, the surfactant SDY-1 can change the contact angle of super-heavy oil–water–rock from 129.7 to 67.4° and reduce the adhesion of crude oil to the rock surface by 99.26%. The oil displacement experiment indicates that the oil washing efficiency of the surfactant SDY-1 can reach 78.7% after ageing at a temperature of 140 °C for 3 days. Compared with petroleum sulfonate flooding, the addition of SDY-1 can improve the displacement efficiency by 33.6%, and the adsorption loss is only 0.651 mg/g oil sand. It has broad application prospects for heavy oil reservoirs with high temperatures, high pressures and high asphaltene contents.

Effect of γ-aminopropyltriethoxysilane on the properties of cellulose acetate butyrate modified acrylic waterborne coatings

Novel waterborne acrylic resin modified by cellulose acetate butyrate was successfully synthesized by a homogeneous solution polymerization with 2-butoxy ethanol, cellulose acetate butyrate and acrylic monomers as raw materials, N, N - dimethyl ethanolamine as neutralization and γ-aminopropyltriethoxysilane (KH-550) as curing agent. The influences of the cellulose acetate butyrate and curing agent content on the properties of the waterborne acrylic resin were investigated. As a curing agent, KH-550 not only improved the cross-linking density of the resin effectively, but also bonded to the substrate to form a molecular layer of silane. Cellulose acetate butyrate and KH-550 were found to reduce the curing temperature of the resin. The tensile strength of the coating added with the curing agent (5.89 MPa) was significantly improved compared to that of cellulose acetate butyrate modified resin (1.49 MPa). This kind of environment-friendly waterborne acrylic resin has a strong potential application in wood coatings, automobile coatings and other fields.

Polyelectrolyte-colloid complex formation via polymerization: reaction kinetics in direct micelles, inverted micelles, and homogeneous solution studied by NMR and conductometry

Formation of polyelectrolyte-surfactant complexes (PESCs) in polymerization process of corresponding amphiphilic monomer is a promising way of pure stoichiometric PESC obtained in salt-free systems. Polymerization of micelle-forming monomer dodecylammonium 2-acrylamido-2-methylpropanesulfonate (DDA-AMPS) in different media was studied by means of 1H-NMR and conductance measurements. Kinetics of polymerization in direct micelles, inverted micelles, and homogeneous solution was considered in terms of classical solution polymerization and microemulsion polymerization. Reaction orders on monomer and initiator were measured in water and dioxane. The rate of polymerization is strongly dependent on monomer micelle existence, being considerably higher in micellar solution than in homogeneous one.

Waterborne acrylic resin modified with glycidyl methacrylate (GMA): Formula optimization and property analysis

Novel waterborne acrylic resin modified with glycidyl methacrylate (GMA) was successfully synthesized via homogeneous solution polymerization in isopropyl alcohol followed by solvent exchange with water. Aminopropyltriethoxysilane (KH-550), a silane coupling agent that can crosslink with resin and iron base material, was used as curing agent for solidifying this GMA modified resin. The cured mechanism of the coating was also investigated by 29Si nuclear magnetic resonance (29Si NMR) spectra and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The waterborne acrylic resin was sprayed on the iron base material and cured by KH-550 for 30 min at 100 °C to form the desired coating. The GMA and KH-550 were found to significantly decrease the curing temperature of this two-component waterborne resin. The thermal property of the coatings with different GMA loadings was investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The GMA enhanced the thermal stability of the coatings from 100 to 400 °C. The modification of GMA was found to reinforce significantly the mechanical properties of the coatings. The tensile strength of coating modified with 15 wt% GMA got a 78.65% improvement compared to that of unmodified resin. The surface hydrophobicity of the coatings does get affected by this modification. The contact angle got increased from 87.72°of the unmodified resin coating to 99.51°of coating modified with 15 wt% GMA. This work opens a new way to synthesize high performance waterborne acrylic resin and reports on the anti-flash corrosion of waterborne coatings on the iron base material surface.

Supramolecular Interfacial Polymerization of Miscible Monomers: Fabricating Supramolecular Polymers with Tailor-Made Structures

We have fabricated a series of supramolecular polymers with tailor-made structures and properties through supramolecular interfacial polymerization of miscible monomers. Compared with homogeneous solution polymerization, supramolecular interfacial polymerization is advantageous for fabricating supramolecular polymers with higher molecular weights. Their higher molecular weights are attributed to the higher effective concentration of monomers at the interface than in solutions and diffusion-limited characteristic of supramolecular interfacial polymerization. Moreover, the glass transition temperatures of supramolecular polymers are well tuned by tuning the monomer structures and supramolecular interfacial copolymerization. It is anticipated that this research will further enrich the methodology for fabricating supramolecular polymers with controlled structures and properties through supramolecular interfacial polymerization.

Synthesis and properties biobased waterborne polyurethanes from glycolysis product of PET waste and poly(caprolactone) diol

Novel biobased poly(ester-urethane)s (PUDs) were synthesized by solvent free homogeneous solution polymerization of poly(caprolactone) diol (PCL), castor oil-based polyols (COLs), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and 1,4-butane diol (BD) as the chain extender. The polyurethane dispersions were prepared by adding required amount of triethylamine (TEA) and water. In this work, castor oil-based polyols have been synthesized using the depolymerized oligoester obtained from glycolysis of PET waste with poly(ethylene glycol) (PEG 400) and castor oil. The effects of the soft segments content on the thermal and coatings properties of resulting polyurethane films have been examined by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and measurement of the coatings properties. Phase separation of polyurethane shows a strong correlation with crystallization behaviour of the polyurethane prepared. It is established that all PUD samples containing PCL as a part soft segment with different molar ratio of castor-oil polyol are crystallisable polymers. The results from XRD analysis have showed that highest degree of crystallinity (23 and 22%) is reached in polyurethanes based on the largest content PCL diol (CPU77 and CPU73). The thermal stability of samples based on (COL/PCL molar ratio 0.25:0.75) possesses the best thermal properties but less values hardness coatings which can be ascribed to a decrease of the hard segment i.e. DMPA content in polyurethane dispersions. The long-term stability of polyurethane dispersions has been investigated using UV–vis spectroscopy. The physico-mechanical properties such as hardness adhesion test and gloss of the dried films have also been determined considering the effect of soft segment content on coating properties.

Enzyme-Initiated Reversible Addition–Fragmentation Chain Transfer Polymerization

Biocatalysis is promising for sustainable production of polymers. Enzyme-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization is reported. Horseradish peroxidase (HRP) catalyzes oxidation of acetylacetone (ACAC) by hydrogen peroxide to generate ACAC radicals, which in the presence of a suitable chain transfer agent initiate efficient and well-controlled RAFT polymerization in aqueous buffer solution at room temperature. The versatility of HRP-initiated RAFT polymerization was demonstrated by controlled polymerization of a wide range of monomers, including both more and less activated monomers, under a variety of conditions, including both homogeneous solution polymerization and heterogeneous dispersion polymerization conditions. In all cases, the polymerization afforded excellent pseudo-first-order kinetics, predictable molecular weights, and narrow molecular weight distributions. Operation via RAFT mechanism of this HRP-initiated polymerization was confirmed by a combination o...

Rheological Behavior of Environmentally Friendly Castor Oil-Based Waterborne Polyurethane Dispersions

Novel biorenewable, waterborne, castor oil-based polyurethane dispersions (PUDs) were successfully synthesized via homogeneous solution polymerization in methyl ethyl ketone followed by solvent exchange with water. Small-amplitude oscillatory shear flow experiments were used to systematically investigate the rheological behavior of these environmentally friendly, biorenewable, aqueous dispersions as a function of angular frequency, solid content, and temperature. In addition, the morphology of the dispersions was investigated at 60 °C for different time intervals using transmission electron microscopy (TEM). The solid content and temperature were found to significantly affect the rheological behavior of the PUDs. The composition dependency of the complex viscosity (η*) was found to be well described by the Krieger–Dougherty equation. Thermally induced gelation was observed for PUDs with a solid content ≥27 wt %. Although the viscoelastic behavior of the PUDs was well described by the time–temperature supe...

The synthesis, characterization and biocompatibility of poly(ester urethane)/polyhedral oligomeric silesquioxane nanocomposites

The primary goal of this study is to develop a facile and inexpensive synthesis method for a new biodegradable and biocompatible poly(ester urethane) (PEU)/polyhedral oligomeric silesquioxanes (POSS) nanocomposite via in situ homogeneous solution polymerization reaction into prescribed macromolecular structure and properties including improved biocompatibility, thermal and hydrolytic stability, and stiffness and strength. Cell culture studies, nuclear magnetic resonance spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetry, and dynamic mechanical analysis measurements were used to confirm the structure and property improvements. The results show that the targeted PEU/POSS nanocomposites (which are remarkably different from conventional polymers, polymer nanocomposites and microcomposites) have significant improvements in mechanical properties and degradation resistance at small POSS concentrations (≤6wt%). The nanocomposites exhibited excellent support for cell growth without any toxicity. POSS concentration did not affect cell adhesion or cell growth, but it significantly changed the surface structure of the PEU into a 3-dimensional matrix with regular pores that may allow cells to better access the growth factors/nutrients, waste exchange, and tissue remodeling. The PEU/POSS nanocomposites were resistant to degradation over a period of six months when exposed to a buffer solution. These desirable characteristics suggest that the nanocomposites may hold great promise for future high-end uses such as in biomedical devices, especially at cardiovascular interfaces.

Synthesis and characterization of novel biodegradable and biocompatible poly(ester-urethane) thin films prepared by homogeneous solution polymerization

Novel biodegradable and biocompatible poly(ester-urethane)s were synthesized by in situ homogeneous solution polymerization of poly(ɛ-caprolactone) diol, dimethylolpropionic acid (DMPA), and methylene diphenyl diisocyanate in acetone followed by solvent exchange with water. The effects of the DMPA content and hard segment content on the properties of the polyurethanes were measured by DSC, TGA, and hydrolytic degradation measurements. The results showed that DMPA had a dramatic effect on the particle size; the particle size decreased rapidly with increasing DMPA content. The hydrolytic degradation test showed that the degradation rate was little affected by the DMPA content in the range investigated, but was observed to be influenced by the hard segment content. Cell toxicity analysis showed that the biodegradable poly(ester-urethane)s synthesized in this study did not exhibit any detectable toxicity to human umbilical vein endothelial cells and mouse embryonic stem cells. Both types of cells can effectively adhere to and spread on the surface of pure poly(ɛ-caprolactone) or poly(ester-urethane)s. The present study demonstrates the feasibility of a facile synthesis of biodegradable polyurethanes and of their aqueous dispersions with prescribed properties for biomedical applications.

Synthesis and Evaluation of a Functional, Water- and Organo-Soluble Nitroxide for “Living” Free Radical Polymerization

The synthesis of a carboxy-functionalized nitroxide based on the 2,2,5-trimethyl-4-phenyl-3-azahexane-3-oxy (TIPNO) structure and the synthesis of two difunctional alkoxyamines have been achieved. Because of the presence of the carboxylic acid function, the nitroxide is organo-soluble in its acidic form and water-soluble in its basic form. Polymerizations of styrene and n-butyl acrylate mediated with the functional nitroxide exhibited all the expected features of a controlled system. The presence of an active chain end was demonstrated by reinitiation of a polystyrene block to form a polystyrene-b-poly(n-butyl acrylate) block copolymer. The ability of the new functional nitroxide to mediate polymerization in homogeneous aqueous solution has also been demonstrated. The polymerization of sodium styrenesulfonate was successfully achieved at temperatures below 100 °C and led to well-defined polymers, providing the first example of nitroxide-mediated radical polymerization (NMP) in homogeneous aqueous solution...

Rheological Behavior of POSS/Polyurethane−Urea Nanocomposite Films Prepared by Homogeneous Solution Polymerization in Aqueous Dispersions

Reinforced polyurethane−urea nanocomposite with reactive polyhedral oligomeric silsesquioxanes (POSS) has been prepared via environmentally friendly aqueous dispersion with no organic solvent. Rheological behavior of this important class of materials has been investigated as a function of POSS concentration over a wide range of shear frequency and temperature (−100 to 230 °C). The functionalized diamino-POSS was reacted initially with isophorone diisocyanate (the urethane hard segments) before adding the polyester diol (the soft segments). The complete reaction of diamino-POSS with urethane segments was confirmed rheologically and morphologically (TEM). The molecular relaxations of the hard and soft segments of PU/POSS nanocomposites were investigated using the rectangular torsional mode in the glassy and rubbery states. It was found that the storage elastic modulus increased systematically only in the high-temperature range (i.e., the range of the Tg of the urethane segments) while the modulus did not si...

The controlled homogeneous organic solution polymerization of new hydrophilic cationic exo‐7‐oxanorbornenes via ROMP with RuCl2(PCy3)2CHPh in a novel 2,2,2‐trifluoroethanol/methylenechloride solvent mixture

AbstractThe authors detail herein the synthesis and controlled polymerization of a series of new permanently cationic ammonium exo‐7‐oxanorbornene derivatives via ROMP, with the first generation Grubbs' catalyst RuCl2(PCy3)2CHPh, in a novel solvent mixture composed of 1:1 vol/vol 2,2,2‐trifluoroethanol (TFE)/methylene chloride. It is demonstrated that this cosolvent mixture is a convenient reaction medium facilitating the polymerization of hydrophilic substrates by hydrophobic initiators under homogeneous conditions. Homopolymerizations and copolymerizations proceed yielding materials with controlled molecular masses, and narrow molecular mass distributions. It is also demonstrated that this protocol is not limited to the use of TFE as a cosolvent and that additional halogenated alcohols, such as 2,2,2‐trichloroethanol and 1,1,1,3,3,3‐hexafluoroisopropanol are also effective cosolvents for the controlled polymerization of such cationic substrates. Finally, it is demonstrated that the TFE/methylene chloride mixture has no apparent detrimental effect on Grubbs' catalyst. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2113–2128, 2007

Reverse Iodine Transfer Polymerization (RITP) in Emulsion

AbstractReverse iodine transfer polymerization (RITP) is a new controlled radical polymerization technique based on the use of molecular iodine I2 as control agent. This paper aims at presenting the basics of RITP and the strategy that we have followed for the development of this process in the past three years, from the validation in homogeneous solution polymerization up to recent results in heterogeneous aqueous polymerization processes. Typical examples of RITP of butyl acrylate in emulsion and RITP of styrene in miniemulsion are discussed.

Nanostructured Polyurethane/POSS Hybrid Aqueous Dispersions Prepared by Homogeneous Solution Polymerization

Aqueous polyurethane dispersions were prepared with 4−10 wt % of functionalized polyhedral oligomeric silsesquioxanes (POSS) via homogeneous solution polymerization in acetone followed by solvent exchange with water. The use of acetone as the initial polymerization solvent allowed for the facile incorporation of both diamino and dihydroxy functional POSS monomers in a homogeneous reaction environment. After addition of water and removal of the acetone, stable dispersions with unimodal particle sizes were obtained. The incorporation of the POSS monomers did not have a significant effect on the dispersion's properties; however, the physical properties of the isolated polymers did display significant changes, with notable increases in storage modulus, Tg, complex viscosity, and surface hydrophobicity. These changes were attributed to the incorporation of the POSS residues into the polyurethane hard segment domains found. Though no sign of any gross phase heterogeneity due to the inclusion of POSS moieties wa...