Main Monomer Research Articles

Study on preparing of diallyl maleate modified acrylic resin

PurposeThere are three double bonds in the chemical structure of diallyl maleate. The purpose of this study is that the acrylate is modified with diallyl maleic anhydride to make the propionate resin present a spatial network structure, thereby improving the performance of the acrylate resin.Design/methodology/approachMethyl methacrylate (MMA) and butyl acrylate(BA) were used as were used as main monomers. Diallyl maleate (DAM) was used as crosslinking monomer and dodecafluoroheptyl methacrylate (DFMA) was used as fluoromonomer. Potassium persulfate (KPS) was used as thermal decomposition initiator, sodium lauryl sulfate (AS) and sodium dodecyl sulfonate (SDS) were used as anionic emulsifiers, and EFS-470 (Alkyl alcohol polyether type nonionic emulsifier) was a non-ionic emulsifier.FindingsThrough optimizing the reaction conditions, the uniform and stable latex is obtained. The polymer of structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and contact angle (CA) were tested on latex films. The particle size and distribution range of emulsion were tested with nano particle size analyzer.Originality/valueThe experimental results showed that the thermal decomposition temperature of the acrylic coating film increased by 20.56°C after modification. In addition, the effect of cross-linking density on the water contact angle of the fluorocarbon groups in DFMA when they migrate to the surface of the latex film during drying has been explored. The experimental results show that a higher degree of cross-linking will hinder the migration of fluorocarbon groups to the surface of the resin film.

Furan Polymers: State of the Art and Perspectives

AbstractThis contribution provides an outlook on the topic of furan polymers, dealing with both its main achievements and the salient recent contributions, together with a critical assessment of their most promising perspectives. Following a brief account of the relevant chemical properties of the furan heterocycle, the main monomers from furfural and hydroxymethylfurfural and their respective polymerization mechanisms are discussed. Chain‐growth polymerizations concentrate on free‐radical and cationic systems, whereas step‐growth polymerizations describe the polycondensation of furfuryl alcohol, polyesters, polyamides, polyurethanes and polyureas, poly(Schiff base)s, epoxy resins, and the polycondensation of 5‐methylfurfural. Finally, the use of the Diels–Alder reaction applied to furan polymer synthesis and modification is reviewed.

Interaction of mulberry anthocyanins with soybean protein isolate: effect on the stability of anthocyanins and protein in vitro digestion characteristics

SummaryThe interactions of anthocyanins and proteins might mutually influence each other on the physicochemical and functional properties. In this study, the interaction mechanism of soybean protein isolate (SPI) with mulberry anthocyanins (MA), and its effect on the thermal stability of anthocyanins and protein subunits’ digestibility were investigated through multiple spectroscopies and in vitro gastrointestinal models. Results showed that cyanidin‐3‐O‐glucoside (C3G), the main anthocyanin monomer in MA, could bind to SPI through hydrophobic interactions, resulting in static fluorescence quenching of SPI. The secondary structure of SPI changed by binding to C3G, with an increase of β‐sheet and a decrease of α‐helix and random coil. The formation of the SPI‐MA complexes improved the thermal stability of MA at 353 K, while, no significant protection occurred during heating at 368 K. Complexation with MA promoted the digestibility of SPI by pepsin, especially the α′ and α subunits of β‐conglycinin and the basic subunit of glycinin, and slightly delayed the digestibility of SPI under intestinal fluid. These results provide an in‐depth understanding of the influence of the protein‐anthocyanin interactions on the stability of anthocyanins and protein digestibility.

Electrochemically Initiated Synthesis of Polyacrylamide Microgels and Core-shell Particles.

Herein, we developed a simple procedure for synthesizing micrometer-sized microgel particles as a suspension in an aqueous solution and thin films deposited as shells on different inorganic cores. A sufficiently high constant potential was applied to the working electrode to commence the initiator decomposition that resulted in gelation. Under hydrodynamic conditions, this initiation allowed preparing different morphology microgels at room temperature. Importantly, neither heating nor UV-light illumination was needed to initiate the polymerization. Moreover, thin films of the cross-linked gel were anchored on different core substrates, including silica and magnetic nanoparticles. Scanning electron microscopy and transmission electron microscopy imaging confirmed the microgel particles’ and films’ irregular shape and porous structure. Energy-dispersive X-ray spectroscopy indicated that the core coating with the microgel film was successful. Dynamic light scattering measured the micrometer size of gel particles with different combinations of acrylic monomers. Thermogravimetric analysis and the first-derivative thermogravimetric analysis revealed that the microgels’ thermal stability of different compositions was different. Fourier-transform infrared and 13C NMR spectroscopy showed successful copolymerization of the main, functional, and cross-linking monomers.

Differential action of pro-angiogenic and anti-angiogenic components of Danhong injection in ischemic vascular disease or tumor models

ObjectiveWe investigate the chemical basis and mechanism of angiogenesis regulation by a multicomponent Chinese medicine Danhong injection (DHI).MethodsDHI was fractionated and screened for angiogenesis activities by in vitro tube formation and migration assays. The composition of DHI components was determined by UPLC. The effects of the main active monomers on angiogenesis-related gene and protein expression in endothelial cells were determined by qPCR and Western blotting analyses. Mouse hind limb ischemia and tumor implant models were used to verify the angiogenesis effects in vivo by Laser Doppler and bioluminescent imaging, respectively.ResultsTwo distinct chemical components, one promoting (pro-angiogenic, PAC) and the other inhibiting (anti-angiogenic, AAC) angiogenesis, were identified in DHI. PAC enhanced angiogenesis and improved recovery of ischemic limb perfusion while AAC reduced Lewis lung carcinoma growth in vivo in VEGFR-2-Luc mice. Among the PAC or AAC monomers, caffeic acid and rosmarinic acid upregulated TSP1 expression and downregulated KDR and PECAM expression. Caffeic acid and rosmarinic acid significantly decreased while protocatechuic aldehyde increased CXCR4 expression, which are consistent with their differential effects on EC migration.ConclusionsDHI is capable of bi-directional regulation of angiogenesis in disease-specific manner. The pro-angiogenesis activity of DHI promotes the repair of ischemic vascular injury, whereas the anti-angiogenesis activity inhibits tumor growth. The active pro- and anti-angiogenesis activities are composed of unique chemical combinations that differentially regulate angiogenesis-related gene networks.

Fabrication and mechanical properties of knitted dissimilar polymeric materials with movable cross-links

Movable cross-network elastomer with knitting polymers (KP elastomer) were obtained by bulk polymerization of main chain monomers in presence of host polymer. The two design strategies successfully improve the toughness and stiffness of the KP elastomers.

The Main Anthocyanin Monomer from Lycium ruthenicum Murray Fruit Mediates Obesity via Modulating the Gut Microbiota and Improving the Intestinal Barrier.

Anthocyanins have been shown to exert certain antiobesity properties, but the specific relationship between anthocyanin-induced beneficial effects and the gut microbiota remains unclear. Petunidin-3-O-[rhamnopyranosyl-(trans-p-coumaroyl)]-5-O-(β-D-glucopyranoside) (P3G) is the main anthocyanin monomer from the fruit of Lycium ruthenicum Murray. Therefore, in this study, we investigated the antiobesity and remodeling effects of P3G on gut microbiota through a high-fat diet (HFD)-induced obesity mouse model and a fecal microbiota transplantation experiment. P3G was found to reduce body weight gain, fat accumulation, and liver steatosis in HFD-induced obese mice. Moreover, supplementation with P3G alleviated the HFD-induced imbalance in gut microbiota composition, and transferring the P3G-regulated gut microbiota to recipient mice provided comparable protection against obesity. This is the first time evidence is provided that P3G has an antiobesity effect by changing the intestinal microbiota. Our present data highlight a link between P3G intervention and enhancement in gut barrier integrity. This may be a promising option for obesity prevention.

Cinnamic Aldehyde, the main monomer component of Cinnamon, exhibits anti-inflammatory property in OA synovial fibroblasts via TLR4/MyD88 pathway.

Cinnamon is a wildly used traditional Chinese herbal medicine for osteoarthritis (OA) treatment, but the underlying mechanism remains ambiguous. The purpose of this study is to explore the mechanism of cinnamic aldehyde (CA), a bioactive substance extracted from Cinnamon, on synovial inflammation in OA. A total of 144 CA‐OA co‐targeted genes were identified by detect databases (PubChem, HIT, TCMSP, TTD, DrugBank and GeneCards). The results of GO enrichment analysis indicated that these co‐targeted genes have participated in many biological processes including ‘inflammatory response’, ‘cellular response to lipopolysaccharide’, ‘response to drug’, ‘immune response’, ‘lipopolysaccharide‐mediated signalling pathway’, etc. KEGG pathway analysis showed these co‐targeted genes were mainly enriched in ‘Toll‐like receptor signalling pathway’, ‘TNF signalling pathway’, ‘NF‐kappa B signalling pathway’, etc. Molecular docking demonstrated that CA could successfully bind to TLR2 and TLR4. The results of in vitro experiments showed no potential toxicity of 10, 20 and 50 μM/L CA on human OA FLS, and CA can significantly inhibit the inflammation in LPS‐induced human FLS. Further experimental mechanism evidence confirmed CA can inhibited the inflammation in LPS‐induced human OA FLS via blocking the TLR4/MyD88 signalling pathway. Our results demonstrated that CA exhibited strong anti‐inflammation effect in OA FLS through blocking the activation of TLR4/MyD88 signalling pathway, suggesting its potential as a hopeful candidate for the development of novel agents for the treatment of OA.

Mechanism analysis of gas products from catalytic pyrolysis of tire rubber based on reaction thermodynamics and kinetics

In this paper, the gas products from pyrolysis of tire rubber was respectively studied by fixed bed pyrolysis experiments—gas chromatography analysis and molecular dynamics simulations. The results of experiments showed that the main gas products of pyrolysis were CH4, H2, and C2H4. The simulation results showed that the long rubber chain broke into four main rubber monomers at low temperature: isoprene, styrene, 1,3-butadiene and uncondensated C4H6·. And at higher temperature, the generated monomers were pyrolyzed into small molecule gases. Fe2O3 reduced the final pyrolysis temperature and increased the pyrolysis rate with a good catalytic reactively. And it changed the gas products distribution, in which the proportion of CH4 and H2 were promoted while the proportion of C2H4 was reduced. In order to obtain the thermodynamic and kinetic data of each reaction path, DFT calculation was carried out. The reaction paths of three major radicals H·, CH3·, and CH2 = CH· were further discussed. The results showed that Fe2O3(commercial) promoted the release of CH3· from isoprene monomer and CH3· attack on isoprene monomer and 1,3-butadiene to produce CH4. Moreover, Fe2O3 promoted H· attacking styrene monomer to generate H2.

Comparison of the nutritional and phytochemical composition and antioxidant activities of Aralia elata (Miq.) Seem fruits in Northeast China

Aralia elata ( Miq.) Seem is a wild medicinal and culinary plant. The newly grown shoots are edible, and the stem and root bark are traditional materials used for medicinal extraction. However, few studies have examined the quality and biological activity of the fruit. In this study, we compared the nutritional and phytochemical composition and antioxidant activity of A. elata fruit (AF) picked from five regions (Harbin, Benxi, Raohe, Jiaohe, and Mudanjiang) in Northeast China. AF picked from Harbin had the highest saponin, anthocyanin, and flavonoid contents. UHPLC-MS/MS analyses showed that araloside A was one of the main saponin monomers in AF. The highest arloside A concentration was detected in fruits picked from Harbin and the lowest concentration was detected in fruits picked from Benxi. The relative reactive oxygen species production in cells after pretreatment with AFs from Harbin (50 μg/mL) was 0.78 ± 0.01, second only to those from Raohe. AFs (50 μg/mL) from Harbin had the highest catalase activity (43.61 ± 0.44 U/mg protein), followed by that of the AF collected from Jiaohe, Benxi, Mudanjiang and Raohe. The malondialdehyde levels of the AFs (50 μg/mL) obtained from Benxi, Raohe, Jiaohe, and Mudanjiang were significantly higher than those of the AF obtained from Harbin (2.67 ± 0.15 nmol/mg protein). Compared with AFs from Benxi, Raohe, Jiaohe, and Mudanjiang, the strongest H 2 O 2 scavenging ability (144.95 ± 2.89 mmol TE/100 g dm) was observed for AF from Harbin. The ferric reducing antioxidant power of AFs ranged from 7.70 to 4.52 mmol TE/100 g dm in the order of Harbin > Mudanjiang > Raohe > Jiaohe > Benxi. The results provided support for the selection of the best quality AF and the expanded cultivation of A. elata .

Novel water soluble polymeric sensors for the sensitive and selective recognition of Fe3+/Fe2+ in aqueous media

Fe3+ and Fe2+ are common metal ions in natural water environments and creatures. The development of water-soluble fluorescent sensors for detecting Fe2+/Fe3+ ions was of great significance. In this work, two kinds of boron fluoride dipyrrole (BODIPY) fluorescent small-molecules were synthesized firstly. One of the small molecules contains a thioester bond that can be used as a chain transfer agent to participate in the polymerization process, and the other contains an unsaturated C = C double bond at the meso position. Through the reversible addition-fragmentation chain transfer polymerization (RAFT) polymerization method, methacrylic acid (MAA) and methacrylamide (MAM) were used as the main monomers, and small molecular fluorescent monomers were introduced to the end of the main chain. In this way, fluorescent macromolecules were obtained. The polymers were water soluble owing to the presence of long enough hydrophilic carboxyl and amide chains. These fluorescent probes exhibit high sensitivity to Fe2+/Fe3+, good selectivity, and anti-interference of other ions. The detection limit for Fe2+ was as low as 2.3 × 10−7 M, and the detection limit for Fe3+ can reach up to 4.5 × 10−7 M. The results show that these probes can be used as good sensors to identify Fe2+ and Fe3+. Moreover, the fluorophores could be incorporated into polymer chains as the RAFT reagents and/or functional monomers.

Study on the dispersion mechanism of the polycarboxylic acid dispersant for disperse dyes

Taking C.I. Disperse Blue 79 as the simulation object, the dispersion mechanism of polycarboxylic acid dispersant (poly(SMA-g-IP-MPEG)) for disperse dyes was studied by molecular dynamics simulations. The results show that the hydrophilicity of the dispersant mainly depends on the maleic acid residues; the ionized carboxylate groups of the maleic acid residues provide negative charges that make the dyes repel each other; the hydrophobicity of the styrene residues is the driving force that makes the dispersants adsorb to the dye surfaces; the branched chains grasp the dye crystals like claws, which make the dispersants combine with the dye crystals better. When the ratio of main chain monomer is 3:1 and the branched chain length is larger than 12, the branched chain tends to wrap around the main chain. The repulsion between dyes decreases, thus the dispersion performance becomes worse. When the ratio of main chain monomer is 1:1, the dispersion effect increases with the increase of branched chain length. But when the branched chain length increases to 16, the longer branched chain can adsorb with two dye crystals at the same time, which leads to the decrease of dispersion effect. In general, the main chain monomer ratio had little influence on the dispersion effect. The dispersant with the main chain monomer ratio of 1:1 and the branch chain length of 12 had the best dispersion effect on the dye. The experimental results verified the correctness of the simulation results. The design of polymeric dispersants for disperse dyes should consider not only the improvement of hydrophilicity and charge repulsion to maintain the dispersion stability of disperse dyes in water, but also the binding force between dispersants and disperse dyes. The two interactions determine the dispersion performance of the dispersant for disperse dyes.

Formation and Characterization of Irreversible Sediment of Ginseng Extract.

Sediment is a key issue in the beverage industry. This study confirmed that reversible and irreversible sediments were formed during low-temperature storage of ginseng extract. The first 30 days of storage are the critical period for sediment formation. As the time of storage extends, the chemical composition changes. The composition interaction model verified that the cross-linking of protein–pectin, protein–oxalic acid and Ca2+–pectin was the main cause of the turbidity of ginseng extract. Based on the characterization of irreversible sediment (IRS), there are typical structures of proteins, polysaccharides and calcium oxalate dihydrate (COD) crystals. Glucose, galacturonic acid, aspartate, glutamic acid, leucine, Ca, K, Al, Mg, Na and Fe are the main monomer components. Effective regulation of these ingredients will greatly help the quality of ginseng beverages.

One‐step synthesis of polymer dispersions with large narrow‐size‐distribution particles via heterophase polymerization in the presence of surface‐active water‐insoluble organosilicon macromers

AbstractPolymerizable water‐insoluble surface‐active macromers (SAMs), namely α,ω‐divinylpolydimethylsiloxane (DVPDMS), α,ω‐dipropylmethacrylatepolydimethylsiloxane (DPMPDMS) and α,ω‐pair(vinylbenzyl)polydimethylsiloxane (PVBPDMS), were synthesized and characterized using NMR. The colloidal‐chemical properties of the synthesized compounds were studied in comparison with non‐polymerizable polydimethylsiloxane. Using DVPDMS, DPMPDMS and PVBPDMS as copolymerizable emulsifiers, polystyrene and poly(methyl methacrylate) suspensions with large particles, narrow particle size distribution and with the absence of the residual surfactant in the waste water were obtained. It is shown that in the presence of DPMPDMS it is possible to obtain polymer suspensions with an average particle diameter of 1.6 μm. The proposed mechanism of the effects of the SAMs on the polymerization is based on the copolymerization with the main monomers in the monomer–polymer particle interphases which results in stabilization of the particle protective layers from early stages of the reaction. © 2021 Society of Chemical Industry

Screening and functional evaluation of the glucose-lowering active compounds of total saponins of Baibiandou (Lablab Semen Album)

ObjectiveTo screen for α-glucosidase inhibitor active compounds in the total saponins of Baibiandou (Lablab Semen Album) based on UHPLC-Q-Exactive Orbitrap MS technology and to evaluate its hypoglycemic activity in vivo. MethodsAcarbose was used as the positive control, and the median inhibitory concentration (IC50) was used as the evaluation index of α-glucosidase inhibitory activity to establish an in vitro α-glucosidase inhibition model. Further, UHPLC-Q-Exactive Orbitrap MS technology was used to screen and identify the active compounds of α-glucosidase inhibitors in the total saponins of Baibiandou (Lablab Semen Album) in order to further verify the activity of the main active monomer and to perform homologous modeling and molecular docking of yeast-derived α-glucosidase and human-derived α-glucosidase, while the hypoglycemic activity was evaluated in diabetic mice. ResultsThis study successfully identified 15 compounds with potential α-glucosidase inhibitory activity, including Chikusetsusaponin IVa, from the total saponins of Baibiandou (Lablab Semen Album). Simultaneously, we verified the activity of the main active monomer Chikusetsusaponin IVa, and showed that it has strong α-glucosidase inhibitory activity. The α-glucosidase inhibitory concentration IC50 was (565.2 ± 1.026) μg/mL, and the IC50 of acarbose, which was lower than the positive control, was (706.6 ± 1.058) μg/mL. The docking energies of Chikusetsusaponin IVa were – 6.1 and – 7.7 kcal/mol with yeast-derived α-glucosidase and human-derived α-glucosidase molecules, respectively. Both showed strong binding activity, and the levels of alanine aminotransaminase (ALT), aspartate aminotransaminase (AST), UREA, Creatinine (CREA), and cholesterol (CHO) were significantly decreased by Chikusetsusaponin IVa (P < 0.05). In addition, it could repair damaged liver and pancreas cells of diabetic mice to some extent. ConclusionThis study provides a basis for screening α-glucosidase inhibitors and structural modifications of the total saponins of Baibiandou (Lablab Semen Album).

Rosin-Based Epoxy Vitrimers with Dynamic Boronic Ester Bonds.

Rosin is an abundantly available natural product. In this paper, for the first time, a rosin derivative is employed as the main monomer for preparation of epoxy vitrimers to improve the mechanical properties of vitrimers. Novel epoxy vitrimer networks with dynamic reversible covalent boronic ester bonds are constructed by a reaction between thiols in 2,2′–(1,4–phenylene)–bis (4–mercaptan–1,3,2–dioxaborolane) (BDB) as a curing agent and epoxy groups in the rosin derivative. The rosin-based epoxy vitrimer networks are fully characterized by Fourier transform infrared spectroscopy (FTIR), an equilibrium swelling experiment, and dynamic mechanical analysis (DMA). The obtained rosin-based epoxy vitrimers possess superior thermostability and good mechanical properties. Due to transesterification of boronic ester bonds, rosin epoxy vitrimer network topologies can be altered, giving welding, recycle, self-healing, and shape memory abilities to the fabricated polymer. Besides, the effects of treating time and temperature on welding capability is investigated, and it is found that the welding efficiency of the 20% C-FPAE sample is >93% after treatment for 12 h at 160 °C. Moreover, through a hot press, the pulverized samples of 20% C-FPAE can be reshaped several times and most mechanical properties are restored after reprocessing at 200 °C for 60 min. Finally, chemical degradation is researched for the rosin-based epoxy vitrimers.

Effect of Brucine on Three Chondrocyte Apoptosis Models

With the development of people’s application technology of Strychnine, Strychnine is a relatively common type of medicine in the current clinical treatment of arthritis patients. And in the actual treatment, because strychnine has an important effect on the apoptosis of three kinds of chondrocytes. Better results can often be achieved through the use of horse money, which is of great significance to patients. The analysis of the influence of strychnose on the apoptosis of the three types of chondrocytes has become the focus of research in the academic and industry circles. The purpose of this article is to analyze the impact of Strychnoma chinensis on three chondrocyte apoptosis models. In this paper, by establishing a system for culturing rat chondrocytes in vitro, using nitric oxide in vitro cultured rat chondrocytes to induce their apoptosis, and observing the effect of Strychnine, the main monomer component of Chinese medicine Strychnine, on the cellular and molecular levels. The mechanism of SD rat chondrocyte apoptosis is to explore the establishment of a system for culturing rat chondrocytes in vitro. In this paper, rat chondrocytes cultured in vitro were induced by nitric oxide to induce their apoptosis, and the mechanism of strychnine, the main monomer component of Strychnine, was observed in order to explore the mechanism of strychnine on the apoptosis of SD rat chondrocytes in vitro. The experimental results showed that strychnine induced apoptosis of chondrocytes, and the survival rate of cells during 36h and 48h after administration was 99% and 97%, respectively. Its apoptotic rate decreases with the increase of the dose and time of strychnine.

Preparation and characterization of self-crosslinking acrylic emulsion with different fluorocarbon chain lengths

PurposeFluorine materials have received the keen attention of many researchers because of their water repellency and low surface free energy. The purpose of this paper is to prepare self-crosslinking fluorocarbon polyacrylate latexes containing different fluorocarbon chain lengths by semi-continuous seeded emulsion polymerization technology.Design/methodology/approachMethyl methacrylate (MMA), butyl acrylate (BA), hydroxypropyl methacrylate (HPMA) and fluorine-containing monomers were used as main monomers. The fluorine-containing monomers included hexafluorobutyl methacrylate (HFMA), dodecafluoroheptyl methacrylate (DFMA) and trifluorooctyl methacrylate (TFMA). Potassium persulfate (KPS) was used as thermal decomposition initiator, non-ionic surfactant alkyl alcohol polyoxyethylene (25) ether (DNS-2500) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS) as mixed emulsifier.FindingsThrough optimizing the reaction conditions, the uniform and stable latex is gained. The polymer of structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA) were tested on latex films. The particle size and distribution range of emulsion were tested with nano particle size analyzer. After comprehensively comparing the latexes and films prepared by HFMA, DFMA and TFMA, the performance of DFMA monomer modified is better.Originality/valueThe self-crosslinking acrylic emulsion is prepared via semi-continuous seeded emulsion polymerization, which methyl methacrylate (MMA), butyl acrylate (BA), hydroxypropyl methacrylate (HPMA) and fluorine-containing monomers were used as main monomers. The fluorine-containing monomers were composed of hexafluorobutyl methacrylate (HFMA), dodecafluoroheptyl methacrylate (DFMA) and trifluorooctyl methacrylate (TFMA). Potassium persulfate (KPS) was used as thermal decomposition initiator, non-ionic surfactant alkyl alcohol polyoxyethylene (25) ether (DNS-2500) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS) as mixed emulsifier. There are two main innovations. One is that the self-crosslinking acrylic emulsion is prepared successfully. The other is that the effects of monomers containing different fluorocarbon chain lengths on polyacrylate, such as monomer conversion rate, coagulation rate, mechanical stability, chemical stability, emulsion particle size and storage stability, are studied in detail.

Fabrication of a state of the art mesh lock polymer for water based solid free drilling fluid

Polymers are used widely in various kinds of drilling fluid to maintain the proper rheological properties. However, most of them are not available for high-temperature or salt solutions due to poor temperature and salt resistance. To ameliorate the temperature and salt resistance of polymer used in the solid-free water-based drilling fluid, a novel polymer with a kind of "Mesh-Lock" reinforced network cross structure, named PLY-F [main monomer acrylic acid (AA), acrylamide (AM), functional monomers 2-acrylamide-2-methylpropanesulfonic acid (AMPS) N-vinylpyrrolidone (NVP) and C16DMAAC] were prepared through free radical polymerization of an aqueous solution of organic cross-linking agent pentaerythritol triallyl ether (PTE) as a cross-linking system, Potassium persulfate (KPS) and sodium bisulfite as the initiator for the first time. The surface morphology, crosslinking architecture and temperature and salt resistance of the PLY-F were fully characterized with several means including SEM, FT-IR, 13CNMR, dynamic rheology, and long-term thermal stability. The SEM observation indicated that the PLY-F exhibits a regular “Mesh-Lock” reinforced network cross structure. FT-IR, 13CNMR analysis indicated that the characteristic functional groups of each monomer such as AM, AA, AMPS and NVP were all together in the polymer. The results show that the apparent viscosity retention rate of the PLY-F in the potassium formate solution (with a density of 1.3 g/cm3) was more than 80% after heat rolling for 72 h at 200 °C and the plastic viscosity retention rate reached 90.3%. Moreover, the salt resistance of the polymer can reach the density of 1.4 g/cm3 (potassium formate solution) under 200 °C and the temperature resistance can reach 220 °C under the density of 1.3 g/cm3 (potassium formate solution). Besides, the PLY-F still has good rheological properties in other saturated solutions (NaCl, HCOONa) under 210 °C.

Modulation of the volume phase transition temperature for multi-stimuli-responsive copolymer hydrogels

Thermo-responsive (TR) hydrogels of the LCST (low critical solution temperature) type swell noticeably below their volume phase transition temperature Tc and collapse above Tc. Biomedical applications of these gels (in particular, for controlled delivery of nuclear acids and genes) require fine tuning of the critical temperature. Modulation of Tc is conventionally performed by copolymerization of TR monomers with monomers whose hydrophilicity is higher or lower than that of the main monomers. The most pronounced changes in Tc are observed when TR monomers are copolymerized with anionic or cationic monomers. Introduction of polyelectrolyte monomers into the polymer network induces a strong dependence of its properties on pH and ionic strength of an aqueous solution. A constitutive model is developed to describe the effects of pH and molar fraction of salt in a solution on the critical temperature of TR polyelectrolyte hydrogels. Adjustable parameters are found by fitting equilibrium swelling diagrams on copolymer gels with strongly and weakly dissociating cationic functional groups. The ability of the model to predict Tc is confirmed by comparison of experimental data with results of simulation.