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A deep water plugging system suitable for high temperature and high salt fracture-cavity carbonate reservoir is developed. The system consisted of 2%～5% PAM+1.0%～1.4% phenolic resin+0.01%～0.014% AIBN+2%～5% modified rubber powder. Observed by SEM, the modified rubber particles are evenly embedded in the polymer cross-linked network, which greatly enhanced the stability of plugging agent. The results show that the temperature resistance of the plugging agent can reach 140 ℃, the salinity resistance can reach 2.5×105 mg/L, the breakthrough pressure gradient can reach 8.05 MPa/m, and the plugging rate is up to 90.33%. This system meets the requirements of water plugging operation in high temperature and high salt reservoir. [ABSTRACT FROM AUTHOR]

Hydrogels are a type of high-water content and crosslinked polymer networks, which can produce a volumetric expansion or contraction through a water absorption or loss process under external environmental stimulation. Due to their good biocompatibility and adjustable mechanical properties, hydrogels have attracted wide attentions and have been extensively applied in the fields of tissue engineering, biomimetic deformation and intelligent actuation. Light is a noncontact, fast switching and high spatiotemporal resolution stimulus, and therefore is used to regulate the macroscopic structure and properties of hydrogels through photothermal effects, photochemical reactions or photoisomerization. Among them, photoisomerization of molecular switches has a broader application potential because of its advantages of mild irradiation conditions and high reversibility. In this review, we summarize the state-of-the-art of photoresponsive hydrogels based on molecular photoisomerization, emphasizing the principle of molecular design as well as applications in biomimetic actuation, and eventually address their perspectives and challenges in the future development. [ABSTRACT FROM AUTHOR]

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective In view of the fact that the existing research had not simulated the high temperature ( _>--120 °C) and high pressure (_>-40 MPa) conditions of the foam flooding, and the foam performance was difficult to reflect the real situation on site, the adaptive performance evaluation of five foam systems was carried out at the conditions of fractured vuggy reservoir with constant foam concentration of 1 wt%, pressure of 40 MPa and salinity of 22 X 104 mg/L. Methods The viscosity of foam base solution under different high temperature conditions was studied by high temperature and high pressure rheometer. The foaming volume, defoaming half-life and foam composite index under different high temperature conditions were studied by high temperature and high pressure foaming instrument. The morphology of high temperature foam was observed in situ by stereomicroscope. Result The results showed that the order of foam with strong to weak temperature adaptability was determined as follows: double cross-linked polymer composite foam > differential dispersion gel reinforced foam > nanoblack card reinforced foam > conventional high-temperature foam > high temperature starch gel foam. Conclusions Except for differential dispersion gel reinforced foam, the average diameter of foam of the other four foams showed significant increase trend when the temperature increased from 110 r to 150 °C. The double cross-linked polymer composite foam and differential dispersion gel reinforced foam had better high-temperature resistance. Except for double cross-linked polymer composite foam, for the other four foams, the viscosity, foaming volume, half-life and foam comprehensive index all decreased with the increase of temperature. While the foaming volume of the double cross-linked polymer composite foam increased with the increase of temperature. [ABSTRACT FROM AUTHOR]

Copyright of Silicone Material is the property of Silicone Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to obtain the novel poly（ε-caprolactone）（PCL） cross-linked networks with good shape memory properties, the cross-linked networks of PCL with different molecular weights were prepared by thiol-ene click chemistry method, and its microstructure, thermal properties, mechanical properties and shape memory properties were characterized. The results show that the hydroxyl end of PCL was successfully converted to acrylate-terminated PCL, and almost all the samples show perfect cross-linked network, and the cross-linked polymer has a thermally induced shape memory effect; with the increase of the molecular weight of PCL diol, the melting temperature and crystallinity of the cross-linked network also show an upward trend; the molecular weight of PCL diol has a certain influence on its fixation ability, but regardless of the length of PCL diol, the shape recovery rate of all samples can reach more than 90%. The efficient thiol-ene click chemistry reaction ensures the uniform distribution of PCL chains between cross-linked nodes, the cross-linked network has good network structure, good mechanical and shape memory properties. The exploration of new PCL cross-linked network provides a feasible way for the end functionalization of polymers. [ABSTRACT FROM AUTHOR]

Copyright of Silicone Material is the property of Silicone Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Surfactant Detergent & Cosmetics (1001-1803) is the property of China Surfactant Detergent & Cosmetics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Basic Sciences Journal of Textile Universities / Fangzhi Gaoxiao Jichu Kexue Xuebao is the property of Basic Sciences Journal of Textile Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Silicone Material is the property of Silicone Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Hydrogel can simulate the natural tissue environment, provide structural support for defects and repair bone defects. OBJECTIVE: To summarize and analyze the application progress of hydrogel in bone defect. METHODS: PubMed, CNKI, VIP, and Wanfang databases were searched by computer with the English and Chinese key words of “hydrogel, bone defect” to search the application of hydrogel in bone defect. RESULTS AND CONCLUSION: Hydrogel shows the homogeneity of water. It can simulate human tissue environment, encapsulate its contents with minimal invasion, manipulate and transfer it to surrounding tissues, provide structural support for defect sites, and repair bone defects through internal healing mechanism, which has unique advantages. Among the ion-mediated hydrogels, alginate is the most studied. Because of its polysaccharide structure, the zinc alginate crosslinked hydrogel system is larger, and the chemically crosslinked hydrogel, polymers with high affinity to each other and showing significant solubility in injectable media can be modified to form a covalently connected network at the delivery point. This type of hydrogel is characterized by the addition of protein-derived bioactive substances to form a stable network of chemically cross-linked polymers. Naturally extracted hydrogels such as gelatin, hyaluronic acid and silk fibroin, as well as synthetic polyethylene glycol are easy to obtain and relatively easy to produce. In this series of studies, naturally derived hydrogels show good biocompatibility and natural polymers as thermosensitive hydrogel carriers lack versatility and responsibility. Therefore, the synthesized derived polymers have been used as the basis for modification and binding with natural polymers. [ABSTRACT FROM AUTHOR]

In some extreme environments, polymers are easy to suffer from irreversible damage or degradation, which increases potential safety problems and reduces the service life of the materials. Regarding to the problem of low self-healing rate of the polymer at low temperature, the polymer network with cross-linked multiple hydrogen bonds was prepared by mixing up the polydimethylsiloxanes with amino-terminated flexible molecular chains and malonyl chloride, which were subjected to condensation polymerization at the temperature of −5 ℃ and in Ar atmosphere. The flexible molecular chain effectively reduces the glass transition temperature (Tg≈−120 ℃), indicating that the molecular chain's ability to move still exists under the low temperature conditions, and it is a prerequisite for polymers to self-heal under low temperature conditions. The results show that the self-healing efficiency of the tensile strength of the polydimethylsiloxane cross-linked polymer at −25 ℃ after 40 min is as high as 97%. Through the reversible fracture and formation of multiple hydrogen bonds between N— H and C=O, the rapid self-healing of polymers at room temperature and high-efficiency self-healing at low temperature can be achieved. This study will provide an insight for further preparation of the autonomous self-healing materials under the extreme environments in the future. [ABSTRACT FROM AUTHOR]

In order to achieve high efficiency in the cycloaddition reaction of CO2 under the conditions of mild environment and absence of cocatalyst, two kinds of porphyrin-based porous organic polymers (PPOP-COOH and PPOP-I) were designed and synthesized in this paper. The nucleophilic groups and metal active centers of quaternary ammonium salts were introduced into the polymers by means of pre-modification and post-modification. The two crosslinked polymers showed excellent chemical and thermal stability. The chemical structures and pore structures of the two polymers were characterized, and both of them had hierarchical porous structure with specific surface areas of 302—514 m²/g. Under the condition of 298 K, CO2 adsorption and desorption tests were carried out, and the results showed that CO2 adsorption capacity of carboxylcontaining polymer was greater than that of quaternary ammonium salt containing polymer. The effect of the catalyst on the cycloaddition reaction of CO2 was studied. The results showed that the synergistic effect of Lewis acid metal ions, nucleophiles and multi-pore structure greatly promoted the CO2 cycloaddition reaction. Under moderate conditions (80 ℃, 0.3 MPa, 24 h), the reaction selectivity and conversion were more than 99%, and the polymers still presented good catalytic performances after being reused for many times. [ABSTRACT FROM AUTHOR]

An ortho-diamine monomer, 4-phenoxy-1,2-phenylenediamine (POPDA), was synthesized via two-step reactions. It was randomly copolymerized with 4,4 ’-dicarboxydiphenyl ether (DCDPE), 5-aminoisophthalic acid (APA) and 3,3 ’- diaminobenzidine (DAB) in polyphosphoric acid to yield a new kind of high molecular weight poly(ether ketone benzimidazole) copolymers (PEKBI-x, ‘x’ refers to the molar fraction of POPDA in aromatic diamines (POPDA and DAB). The resultant PEKBI-x was sulfonated using fuming sulfuric acid as the sulfonating reagent to give the corresponding sulfonated poly(ether ketone benzimidazole)s (SPEKBI-x). No significant polymer degradation was observed during the process of sulfonation reaction indicating excellent chemical stability of the copolymers PEKBI-x. A series of covalently crosslinked membranes (SPEKBI-x-CL) were prepared via the solution cast method, and the cross-linking reaction occurred between the amino groups of the APA moiety of the SPEKBI-x and the epoxy groups of the cross-linker 1,2,7,8- diepoxyoctane during the process of solvent evaporation. The thermal stability, mechanical properties, water uptake, swelling ratio, proton conductivity, ion exchange capacity, radical stability, and single cell performance of the exchange proton membranes were investigated. Results showed that these cross-linked membranes exhibited very high ion exchange capacities (2.88～3.28 meq/g) and good mechanical and thermal properties. With the increase of POPDA content in the copolymers, the proton conductivity of the proton exchange membrane increased. A preliminary test of H2-O2 single cell revealed that the maximum output power density of the single cell assembled with the SPEKBI-0.50-CL membrane reached 662 mW/cm2 at 80 ℃, 80% relative humidity and 100 kPa back pressure, which was slightly higher than that of the one assembled with Nafion212 (631 mW/cm2) under the same test conditions. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Crosslinked polymer chains have a remarkable effect on the fundamental properties and cytocompatibility of hydrogels, and crosslinking density can significantly change the formation of polymer chains. There are few studies on the effect of the properties of hydrogels caused by crosslinking density. OBJECTIVE: To prepare a composite hydrogel with a favorable cytocompatibility and to explore the effect of crosslinking density on the properties of the hydrogel. METHODS: Gelatin methacrylate solution was prepared, and decellularized meniscus extracellular matrix and LAP solution were added to prepare the pre-gel solution, which was crosslinked by blue ray. The crosslinking time was 10, 30 and 60 seconds. The compression elastic modulus, swelling ratio and degradability of hydrogels were detected. Meniscus fibrochondrocytes were added into the pre-gel solution, and crosslinked by blue ray. The cell viability, morphology and gathering were detected at 10, 30 and 60 seconds of crosslinking. RESULTS AND CONCLUSION: (1) The hydrogel with 60 seconds of cross-linking time had higher compression elastic modulus than that of the hydrogel with 10 and 30 seconds of cross-linking time (P < 0.05). (2) The swelling ratio of the hydrogel with 10 seconds of cross-linking time was significantly higher than that of the hydrogel with 30 and 60 seconds of cross-linking time (P < 0.05). The swelling ratio of the hydrogels with 30 versus 60 seconds of cross-linking time had no significant difference (P > 0.05). (3) With the crosslinking time increasing, the degradation time of hydrogels increased. The hydrogels with 60 seconds of cross-linking time degraded completely at 80 minutes, and hydrogels with 10 seconds of cross-linking time degraded completely at 50 minutes. (4) After 24 hours of culture, the cell viability in all groups was over 95% (P > 0.05). (5) At 1 day after culture, the cells were in sphere-shape and distributed evenly in all groups. On day 4, the cells in all groups began to extend, and there were small cell masses in the hydrogels with 10 seconds of cross-linking time. On day 7, the dendritic extension in all groups was obvious, and there were dominant cell masses in the hydrogels with 10 seconds of cross-linking time. (6) After 1, 7 and 14 days of culture, cell viability in all groups was over 85%. At 1 day after culture, the cells in the hydrogels with 10 seconds of cross-linking time were in sphere-shape and distributed evenly. On day 28, the cells extended in dendritic shape, and gathered in reticular formation. (7) In summary, the property of gelatin methacrylate/decellularized meniscus extracellular matrix composite hydrogel can be optimized by adjusting crosslinking density. [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the development of polymer flooding, polymer contained blockage was appeared and the oil well production was decreased in SZ36-1 oilfield. In this paper, the components of blockage in polymer flooding injection well (PFIW) and response well (PFRW) were compared by several characterization methods firstly. The inorganic scale was the main substance in collected samples, the mass ratio of inorganic scale and organic scale in PFRW blockage was 4.0-5.5, which was much larger than that of PFIW (0.25-0.75). The inorganic scale mainly was Fe2O3 in PFIW and and CaCO3 in PFIW, and the organic scale was partially hydrolyzed polyacrylamide. Then, the formation mechanisms of inorganic scale and organic scale in PFRW and PRIW were investigated, especially the formation mechanism of blockage in PFRW was studied. In the area which was close to the response oil well, there was a lot of Fe3+ in residual acid solution after the acidification operation, and when it was mixed with polymer flooding solution, Fe(OH)3 was formed as the pH increased and Fe2O3 blockage was formed after the oxidation. In addition, the cross-linked polymer blockage which was organic scale, was formed by the selective coordination between polymer and Fe3+ when the degraded polymer was mixed with Fe3+ solution in acid condition. The results in this paper are helpful for the targeted removal of plugging in PFRW or PRIW and preventive blockage in PRIW. [ABSTRACT FROM AUTHOR]

A series of thermo-responsive core cross-linked star polymers (CCSP), in which poly(methoxypolyethylene glycol-co-di(ethylene glycol) ethyl ether acrylate) (P(PEGA-co-DEGA)) served as the thermo-responsive arm, have been successfully prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization using the “arm-first ” approach. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H-NMR) have been applied to characterize the structure and composition of the resultant polymers. The molecular weight of the P(PEGAco- DEGA) arm and the corresponding CCSP were obtained by gel permeation chromatography (GPC) analysis, which showed that the efflux time of CCSP was significantly shortened compared with its corresponding arm, indicating that the CCSP was successfully prepared. The phase transition behavior of the resultant CCSP was evaluated by UV-Vis spectroscopy. Results showed that the low critical solution temperature (LCST) of CCSP displayed a downward trend with increasing the content of DEGA in the P(PEGA-co-DEGA) arm. The LCST of CCSP was also influenced by the pH value of the solution due to the ionization of the carboxylic acid groups at the end of the polymer chains, leading to an upward trend with the increase of pH value. The experimental results indicated that the LCST of CCSP could be controlled in the range of 49-82 ℃ by adjusting the molar ratios of PEGA to DEGA in the arm and the pH value of the solution. Furthermore, the prepared CCSP demonstrated a narrower temperature range of phase transition, thereby resulting in a faster phase separation process in comparison to the corresponding linear arm. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We developed an adsorbent utilizing the inclusion ability of cyclodextrin (CD). CD polymers were prepared by using glycerin (Gly) and epichlorohydrin (EPC) as crosslinking agents. The synthesized CD-Gly-EPC copolymers were insoluble in water and organic solvents. When the amount of CD was increased, structural analysis of the copolymer suggested that CD was widely dispersed in a branched structure produced by the addition of Gly. The amount of CD introduced into the copolymer was increased with increasing amount of Gly, which was effective to improve the copolymerization efficiency. Bisphenol A and 4-nonylphenol were adsorbed to copolymer prepared with waste glycerin, which is an unwanted byproduct of bio diesel fuel production. The obtained copolymer may be useful as an adsorbent, and we propose a new recycling method for waste Gly. [ABSTRACT FROM AUTHOR]

Due to the short gelation time of the present cross-linked polymer gel system, conformance control agent cannot enter into deep reservoir, resulting in poor water flooding effect. By the crosslinking reaction between the retarding organic composite crosslinking agent NQJ and salt-resistance polymer under thermal stabilizers and specific temperature, the weak gel with space network structure is formed. The weak gel conformance control agent has low surface viscosity, easy injection on-site, and good delayed cross-linking effect, so it can achieve the high-dose injection. The research shows that the mass fraction of salt-resistance polymer, cross-linking agent, and the heat stabilizer are 0.15%-0.25%, 0.15%-0.2%, and 0.015%-0.025% respectively. The viscosity of gel is greater than 5000 mPa·s, and the gelation time is 3~6 days. The weak gel can meet the need of deep reservoir conformance control and oil displacement, and improve the water flooding effect of high water cut oil field. [ABSTRACT FROM AUTHOR]

The thermal behavior of coal-tar pitch with different lignin/silica hybrid (LSH) contents was studied by thermogravimetric analysis (TGA). The optical texture and micro-crystal structure of resultant cokes from carbonization of the coal-tar pitch with different LSH contents were characterized by reflected polarized light microscopy and X-ray diffraction ( XRD), respectively. In addition, the microstructure of resultant cokes was investigated using scanning electron microscopy (SEM) and energy dispersive spectroscopy(EDS). The results show that the thermal stability of coaltar pitch increases with the addition of LSH. Moreover, the addition of LSH markedly changes the optical texture and microstructure of resultant cokes. [ABSTRACT FROM AUTHOR]

Influence of microsphere--crosslinked ratio on the performance of crosslinked polymer microsphere was studied by dynamic light scattering experiments, scanning e-electron microscopy experiments, nuclear pore membrane filtrating experiments and core flooding experiments. The experimental results show that swelling microspheres sizes are different because of different hydration crosslinked ratio; the smaller the crosslinked ratio becomes, the looser microspheres structure is, the larger swelling multiple is. With he decrease of crosslinked ratio, the soft degree of microsphere increased, and the deformability of microsphere enhanced. The nuclear pore membrane filtrating experimental results show that the microspheres with moderate size and better deformability have better blocking ability. The core flooding experiments results further show that the microsphere with better deformability can easier access to the deep reservoir and occur closure. The field application test shows hat the polymer microsphere system can increase oil production and reduce water. [ABSTRACT FROM AUTHOR]

In this paper, the staining mechanism and the influencing factors of wet rubbing fastness of fabrics dyed with reactive dye were analyzed. Then two measures to improve the fastness were put forward, including the method of adequately removing loose color on fabrics and that of introducing cross-linker in dyeing. [ABSTRACT FROM AUTHOR]