10 results about "Chain walking" patented technology

The application provides a double-stranded walking type DNA nanomachine and a preparation method and application thereof, and relates to the technical field of fluorescent analysis and detection.The double-stranded walking type DNA nanomachine for ctDNA fluorescent detection comprises a gold nanoparticle carrier, an anchor probe, a FAM fluorescent reporter probe, a double-stranded walking arm, a Cas12a protein and a crRNA to form a ribonucleoprotein complex.The walking arm of a conventional CRISPR / Cas12a nanomachine is a DNA single-stranded structure, which is easily cut in trans by activated Cas12a, thereby reducing the stability and sensitivity of the nanomachine.The application introduces a double-stranded DNA structure into the walking arm design to replace the conventional DNA single-stranded walking arm, constructs a double-stranded walking type three-dimensional DNA CRISPR / Cas12a nanomachine, effectively resists the reverse cutting of Cas12a on the walking arm, maintains the structural integrity and functional stability of the nanomachine, and greatly improves the detection sensitivity and specificity of lung cancer ctDNA, thereby having a good clinical application prospect.

The application discloses a graphene composite fiber medical elastic fabric glove, and belongs to the technical field of medical polymer materials. Raw materials thereof include medical grade ethylene-alpha-olefin polyolefin elastomer, branched polyethylene, graphene modified branched polyolefin and the like; wherein the graphene modified branched polyolefin is prepared through catalyst covalent anchoring-in-situ chain walking polymerization, realizing good dispersion of graphene in the matrix. The glove solves the pain points in the prior art, such as easy agglomeration of graphene, decline of barrier performance after stretching, insufficient biological safety and the like, and through synergistic effect of raw materials and structure optimization, mechanical strength, elastic recovery, dynamic barrier, antibacterial and antistatic performances are simultaneously improved. The product has no latex allergy risk, low heavy metal residue and excellent biocompatibility, and can meet the needs of high-end medical scenes such as operating rooms and clinical laboratories, and has industrialization adaptability and environmental protection value.

This invention provides a highly thermally stable, photoresponsive α-diimine nickel complex, its synthesis method, and its applications, aiming to develop novel olefin polymerization catalysts with both excellent thermal stability and photoresponsive properties. The core photoresponsive switch of this type of nickel complex is a rigid diphenylethylene derivative, which can achieve reversible photoisomerization of the E / Z configuration under 365 nm and 405 nm ultraviolet light irradiation: the E configuration has a relatively open coordination environment; after light irradiation, the Z configuration has a more compact spatial structure, which can form a dual regulatory mechanism: steric hindrance and potential metal-aryl π interactions. Due to this dual regulatory mechanism, the complex exhibits excellent thermal stability at 150 °C. o Even at high temperatures, it still maintains a high value of 0.8 × 10⁻⁶. 6 g·mol ‑1 ·h ‑1 The nickel complex of this invention exhibits enhanced catalytic activity and effectively inhibits chain transfer and chain walking reactions during high-temperature polymerization. By synergistically enhancing thermal stability through configurational tautomerism, and possessing both photoresponsive properties and high catalytic activity, it holds significant research value and broad application prospects in the precise synthesis of functionalized polyolefin materials.

The present invention discloses a hyperbranched multi-arm reversible cross-linked resin, its preparation, and application as an adhesive. The preparation method of the hyperbranched multi-arm reversible cross-linked resin comprises: step 1, using an α-diimine palladium catalyst to catalyze the copolymerization of ethylene and a reversible cross-linking functional monomer A shown in formula I based on a "chain walking" mechanism to obtain a hyperbranched polyethylene reversible cross-linking agent; step 2, using 2-bromoisobutyryl bromide as an initiator, and using ordinary monomers and a reversible cross-linking functional monomer B shown in formula IV as comonomers, and synthesizing a linear reversible cross-linked polymer by atom transfer radical polymerization; step 3, cross-linking the hyperbranched polyethylene reversible cross-linking agent and the linear reversible cross-linked polymer in a solvent to obtain a hyperbranched multi-arm reversible cross-linked resin. The present invention provides the application of the hyperbranched multi-arm reversible cross-linked resin as an adhesive, which has excellent bonding properties and recyclability and is suitable for large-scale application. #imgabs0##imgabs1#

The present disclosure relates to an α-diimine ligand compound, its metal complex, an α-diimine metal-supported catalyst and its application, belonging to the fields of catalytic olefin polymerization and synthesis of high molecular polyolefin materials. The ligand compound has the structural formula shown in formula (I), wherein R1, R2, R3, and R4 are each independently selected from any one of C1-C 11 alkyl, substituted or unsubstituted diphenylmethyl, and hydrogen; R5 is selected from any one of methoxy, hydroxy, and sodium oxy substituents. When there is a substituent on the diphenylmethyl, the substituent is selected from C1-C 11 alkyl, C1-C 11 alkoxy, and C2-C 11 alkenyl. The ligand compound of the present disclosure regulates the steric hindrance by the selection of the backbone of the diimine and the R5 group, and inhibits the chain walking of the subsequently formed metal complex.

The invention relates to the technical field of polyolefin materials and coordination catalysis, and discloses a preparation method of a biphenyl-based binuclear alpha-diimine nickel catalyst and application of the biphenyl-based binuclear alpha-diimine nickel catalyst in ethylene chain walking polymerization. The catalyst disclosed by the invention is excellent in thermal stability, and has higher catalytic activity compared with a traditional diimine nickel catalyst; the polyolefin obtained through catalysis is narrow in molecular weight distribution, and the branching degree and the melting point can be accurately regulated and controlled through ligand substituent groups; the preparation process is simple and convenient, the catalyst can be used for homopolymerization and copolymerization of ethylene, propylene and alpha-olefin, products contain functional polyolefins such as high-melting-point polyethylene and high-branching-degree polyolefins, and the catalyst has important application value in the field of synthesis of high-performance polyolefin materials.

The application discloses a method for preparing semi-crystalline polar polyolefin materials by using a nickel catalyst to catalyze long-chain alpha-olefin chain extension polymerization. The semi-crystalline polyolefin material provided by the application uses an alpha-diimine nickel complex as a main catalyst, adds a cocatalyst to form a catalytic system, and can catalyze long-chain alpha-olefin and various polar monomers to copolymerize. Based on the chain extension polymerization mechanism of the catalyst, the semi-crystalline polar polyolefin material with a polyethylene-like structure can be obtained. The alpha-diimine nickel catalyst used in the method is cheap and easy to obtain. By regulating the steric hindrance of the nickel catalyst ligand, the type of long-chain alpha-olefin and the reaction condition, the melting point, the crystallinity and the polar monomer insertion rate of the obtained semi-crystalline polar polyolefin material can be regulated. By changing the type of copolymerization polar monomer, different polar functional groups can be introduced into the semi-crystalline polar polyolefin material, so that the diversified requirements for the structure and performance of the polymer can be met, and the method has a good application prospect.

The application discloses a long-chain star-shaped hyperbranched terpolymer, a thermoreversible dynamic crosslinking thermoplastic elastomer and a preparation method of the thermoplastic elastomer. The long-chain star-shaped hyperbranched terpolymer is prepared by the following method: a macromolecular initiator containing a terminal bromine is obtained by catalyzing copolymerization of ethylene and BIEA monomers by a Pd-diimine catalyst through a chain walking mechanism; and the long-chain star-shaped hyperbranched terpolymer is synthesized by using the macromolecular initiator as an initiator, furfuryl methacrylate and styrene as comonomers, PMDETA as a ligand and CuBr as a catalyst through atom transfer radical polymerization. The application provides a thermoplastic elastomer which is obtained by crosslinking and curing of the long-chain star-shaped hyperbranched terpolymer and a curing agent. The application introduces furan groups into hyperbranched polyethylene, realizes dynamic reversible covalent bond modification, and makes the thermoplastic elastomer have a thermoreversible property, thereby promoting recycling and secondary use of the material.

The application provides a quinoline pyridine nickel pre-catalyst and a preparation method and application thereof. The nickel pre-catalyst is 8-(2,6-di(aryl)-3,4,5-trifluorophenyl) imino-5,6,7-trihydroquinoline pyridine. Under the protection of inert gas, a ligand L is prepared by using 5,6,7-trihydroquinoline-8-ketone and synthetic aniline A, and the ligand L is reacted with (DME)NiBr2 to prepare a series of nickel pre-catalysts Ni R ; the nickel pre-catalyst is activated by methylaluminoxane (MAO) and used for ethylene polymerization catalytic performance experiment, the nickel pre-catalyst shows high catalytic activity (3.1×10 6 g mol ‑1 h ‑1 ), and produces controllable polyethylene with chain walking (branching degree = 58-90 / 1000C), chain transfer (polymer M w = 0.7-2.8 kg mol ‑1 ) and chain termination reaction (vinylidene / ethylene = 83.4-93.6%) and the like. It is worth noting that the beta-elimination reaction is the main chain termination mode in the system, so that the obtained polyethylene can change from polyethylene wax to viscous oil with the change of polymerization temperature, and further produce polyethylene with a higher internal double bond ratio.

The application relates to the technical field of olefin polymerization, and discloses a catalyst and a preparation method and application thereof. The catalyst comprises component A, an organic aluminum compound and a post-transition metal complex; wherein the component A is MXene and / or modified MXene; the modified MXene contains a structure shown in formula (I); in the formula (I), M is selected from carbon, silicon, aluminum and boron; R is an alkyl group; X is halogen; n and m are integers from 0 to k, n and m are not 0 at the same time, and k-n-m>=1; and k is the valence state of M. The catalyst is prepared by matching MXene and / or modified MXene and an organic aluminum compound, the chain walking ability of the catalyst is improved, and complex ligand design and synthesis are not needed. When the catalyst is used for catalyzing olefin polymerization, the branching degree of the obtained product is improved, the proportion of branched chains can be adjusted, and the content of long branched chains with a length of more than C6 is improved.