1214 results about "Chain transfer" patented technology

The invention provides a perfluoroether rubber sealing element and a preparation method thereof, and the preparation method comprises the following steps: taking tetrafluoroethylene and perfluoroalkyl vinyl ether as comonomers, and carrying out emulsion polymerization under the condition of a vulcanization point monomer and a chain transfer agent to obtain raw perfluoroether rubber; the preparation method comprises the following steps: mixing the raw perfluoroether rubber, the carboxyl fluorinated modified carbon nanotubes, a filler, a vulcanizing agent and an accelerant, and performing first-stage vulcanization and second-stage vulcanization to obtain the perfluoroether rubber sealing element. According to the perfluoroether rubber sealing element and the preparation method thereof provided by the invention, the compressive deformation resistance of the perfluoroether rubber sealing element is improved by adding the carboxyl fluorinated modified carbon nanotubes, so that the sealing element is ensured to meet the sealing requirement of semiconductor equipment.

The invention discloses a novel modified starch-based polycarboxylate superplasticizer and a preparation method thereof, and belongs to the technical field of concrete admixtures. The preparation process comprises the following steps: (1) performing acidolysis treatment on starch to obtain acidolysis starch; (2) modifying the acidolysis starch and a double-bond modifier under the action of auxiliaries such as a polymerization inhibitor to prepare novel double-bond-containing modified starch (AS); (3) mixing AS and a polyether macromonomer in water to form a base solution; (4) dropwise adding an acrylic monomer and a chain transfer agent into the base solution, and carrying out a copolymerization reaction through an initiation system; and (5) insulating and neutralizing to obtain a finished product. In order to solve the problems of non-renewable petroleum-based raw materials, high production cost and the like of the traditional polycarboxylate superplasticizer (PCA), active double bonds are introduced into modified starch by a solvent-free semi-dry process to replace part of polyether macromonomers, so that the polymerization activity and grafting ratio of the modified starch are effectively improved, the water-reducing dispersion effect of the modified starch is enhanced, and the water-reducing property of the modified starch is improved. The water reducer has the advantages of low mixing amount, high water reduction and the like, and has economic and environmental benefits.

The present invention belongs to the technical field of coating chemical industry, and specifically discloses a high-hardness self-cleaning antifouling resin, coating, and preparation method and application thereof. The raw material components of the resin include by weight: 2-10 parts of a first monomer, 25-40 parts of a second monomer, 3-20 parts of a third monomer, 0.5-1 parts of an initiator, 0.1-0.5 parts of a chain transfer agent, and 46-50 parts of a first solvent; wherein: the first monomer is an aminoacrylic acid monomer, the second monomer is a long-chain acrylate monomer, and the third monomer is an organosilicon monomer. The coating prepared by the present invention can achieve long-term and effective functions such as high hardness, weather-resistant self-cleaning and corrosion resistance.

The invention discloses deep eutectic gel polymer electrolyte as well as preparation and application thereof, belongs to the technical field of battery electrolyte, solves the problems of low thermal stability, low ionic conductivity and poor mechanical property in the prior art, and comprises a bimetallic salt-eutectic solvent and a polymer chain which are dynamically crosslinked and constructed, the bimetallic salt-eutectic solvent comprises lithium ions, heterogeneous metal salt and Lewis base, and the polymer chain is formed by free radical polymerization, atom transfer radical polymerization (ATRP) or reversible addition-fragmentation chain transfer radical polymerization (RAFT). According to the invention, the deep eutectic solvent is introduced as a reaction solution, so that the organic gel monomer is subjected to photopolymerization or thermal polymerization in the solution, the elongation at break can reach more than 500%, the organic gel has excellent mechanical stretchability, a polymer network is formed by utilizing a long-chain molecular formula of a polymer chain, the deep eutectic solution is wrapped in the polymer network, and the organic gel has excellent thermal stability; and the good ionic conductivity of the electrolyte is ensured.

The invention discloses a concrete polycarboxylic acid water reducing agent with high slump loss resistance and flocculation resistance and a preparation method of the concrete polycarboxylic acid water reducing agent, and belongs to the technical field of concrete admixtures. The water reducing agent is prepared from the following raw materials in parts by weight: 45 to 55 parts of isopentenyl polyoxyethylene ether, 3 to 8 parts of methacrylic acid phosphate, 8 to 12 parts of hydroxyethyl acrylate, 4 to 7 parts of N-isopropylacrylamide, 10 to 15 parts of auxiliary monomer, 8 to 12 parts of initiator and 0.3 to 0.6 part of chain transfer agent. And the technical problems that the fluidity of the concrete is reduced and the slump retaining effect is poor due to the fact that the temperature of the concrete is increased in the stirring process are solved.

The invention discloses a bionic lignin-based saline-alkali soil improvement material and a preparation method thereof, and belongs to the technical field of high polymer materials and soil improvement. According to the saline-alkali soil improving material, lignin or a derivative thereof serves as a framework, glutenin charge distribution and a dynamic disulfide bond sodium ion response function are simulated, and the sequence and the proportion of chain segments of sulfonic acid groups and quaternary ammonium salt groups are accurately regulated and controlled through step-by-step activation and alternate copolymerization in an aqueous solution polymerization reaction system; positive and negative charges form more uniform sequence distribution, so that the amphipathy of the lignin compound is realized; then, sulfydryl is introduced through click chemistry, linear regulation and control of material viscosity and water solubility are achieved through the chain transfer characteristic of multi-sulfydryl functional groups, and the requirements of different saline-alkali soil application scenes are met. The limitation that a traditional lignin product is single in function is broken through, efficient utilization of lignin is achieved, and the intelligent saline-alkali soil improvement material integrating high stability and pH and Na < + > multi-environment response is developed.

The invention discloses a special grinding aid for gold ore and a preparation method thereof, and belongs to the technical field of mineral processing, the special grinding aid for gold ore comprises the following raw materials: a monomer, an initiator, a chain transfer agent and a solvent; the monomers are an unsaturated polyether monomer A and an unsaturated carboxylic acid monomer B; or a monomer C containing an ethylenically unsaturated sulfonic acid group. The preparation method comprises the following steps: putting the raw materials into a water bath kettle, and polymerizing in a separate dropwise adding manner to prepare the special grinding aid for the gold ore. The prepared grinding aid can improve the problems of particle agglomeration, low fine grinding efficiency, low gold dissociation efficiency and the like in the gold ore grinding process, the concentrated utilization of the grinding aid limited in the fields of cement, ceramics and the like is improved, the grinding energy consumption can be reduced, and the material quality can be improved.

The invention relates to the technical field of concrete admixtures, in particular to a high-performance polycarboxylate superplasticizer and a preparation method thereof. The high-performance polycarboxylate superplasticizer comprises the following components: a polycarboxylate superplasticizer and modified cellulose ether, the polycarboxylate superplasticizer is prepared by polymerization reaction of vinyl polyether macromonomer, unsaturated carboxylic acid and functional monomer under the action of initiator and chain transfer agent. According to the high-performance polycarboxylic acid water reducing agent provided by the invention, the polycarboxylic acid water reducing agent and the modified cellulose ether are compounded and applied to concrete, the initial fluidity of the concrete is good, the slump retaining property is good, the water-retaining property, the wrapping property and the cohesiveness of the concrete are good, and the segregation and bleeding phenomena are avoided when the concrete is mixed with the high-performance polycarboxylic acid water reducing agent.

The invention provides a lubricant with a modified silicon carbide particle structure coated with a resin material for a drilling fluid as well as a preparation method and application of the lubricant, and belongs to the technical field of lubricants for oil field drilling fluids. The preparation method of the lubricant comprises the following steps: adding pretreated nano SiC particles, hydroxyethyl acrylate, dodecyl acrylate and a silane coupling agent into base oil, then adding a chain transfer agent, stirring, and then adding an initiator for reaction; after the reaction is finished, filtering, washing and drying to obtain modified nano SiC particles; and adding the modified nano SiC particles into the fluorocarbon resin solution, heating for reaction, drying and grinding to obtain the fluorocarbon resin. The invention develops a novel efficient lubricant material for the drilling fluid, and the lubricant material not only can greatly reduce the flow resistance of the drilling fluid and the friction resistance coefficient of a filter cake and slow down the wear of a drilling tool, but also has excellent wear resistance and corrosion resistance, and can effectively improve the drilling efficiency and prolong the service life of a drill bit.

The invention discloses polymer graft modified graphene oxide as well as a preparation method and application thereof, and belongs to the field of building materials. The polymer grafted modified graphene oxide comprises graphene oxide and a polymer grafted on the surface of the graphene oxide through an ester bond, and the grafting mass ratio of the graphene oxide to the polymer is 1: (0.15-0.75). The preparation method of the polymer grafted modified graphene oxide comprises the following steps: firstly, carrying out esterification reaction on hydroxyl on the surface of graphene oxide and a reversible addition-fragmentation chain transfer polymerization (RAFT) chain transfer agent to generate GO of which the surface is grafted with the RAFT chain transfer agent; and adding a methacrylic acid monomer and an initiator, and carrying out RAFT polymerization on the surface of the GO to obtain a target product. The polymer grafting modified graphene oxide provided by the invention can achieve the effects of high polymer grafting ratio and capability of improving the fluidity of cement paste.

The invention relates to the technical field of optical cement, in particular to high-temperature-resistant and high-humidity-resistant OCA (Optical Clear Adhesive) as well as a preparation method and application thereof. The high-temperature-resistant and high-humidity-resistant OCA optical adhesive is prepared from 40 to 55 parts of a soft monomer, 10 to 25 parts of a hard monomer, 5 to 20 parts of a functional monomer, 5 to 15 parts of a thiourea monomer, 3 to 15 parts of a polyurethane acrylate prepolymer, 0.2 to 2 parts of a photoinitiator, 0.05 to 2 parts of a chain transfer agent, 0.1 to 1 part of a tackifying coupling agent, 0.1 to 1.5 parts of an antioxidant, 0.05 to 1 part of a flatting agent and 0.05 to 1.5 parts of a cross-linking agent, the polyurethane acrylate prepolymer is mainly prepared from polyol, polyisocyanate and hydroxyl-containing acrylate through a reaction. The OCA optical cement disclosed by the invention not only has the characteristic of high light transmittance, but also can keep good adhesion, stability and durability in a high-temperature and high-humidity extreme environment.

The invention discloses a C6 monomer polycarboxylate superplasticizer and a preparation method thereof. The C6 monomer polycarboxylate superplasticizer is prepared from the following raw materials in parts by mass: 300-380 parts of C6 ethylene glycol monovinyl polyglycol ether polyether macromonomer, 7.5-11.0 parts of acrylic acid, 0.3-1 part of chain transfer agent, 0.15-1.0 part of reducing agent and 0.6-1.2 parts of oxidizing agent. The water reducing agent prepared by the invention has the advantages of simple process, energy conservation, environmental protection, shortened synthesis time, improved production efficiency, high adaptability and better water reducing property.

The invention discloses a single-chain nanoparticle composite reinforced and toughened plastic material and a preparation method thereof, and belongs to the technical field of polymer plastics. The reinforced and toughened plastic material is prepared from the following raw materials in parts by weight: 10 to 20 parts of polymer monomer, 0.004 to 0.005 part of initiator, 0.05 to 0.06 part of chain transfer agent, 8 to 12 parts of solvent and 0.1 to 0.2 part of functional filler, the preparation method specifically comprises the following steps: (1) weighing the raw materials; (2) uniformly mixing the raw materials, and performing nitrogen atmosphere replacement and polymerization reaction; and (3) re-precipitating, and drying in vacuum to obtain the product. The reinforced and toughened plastic material disclosed by the invention not only has excellent performance in the aspect of tensile property, but also shows excellent mechanical response under a bending-resistant load, and is suitable for engineering plastic application scenes with relatively high requirements on structural stability and use safety.

The invention relates to a method for preparing a degradable polyacrylamide fracturing fluid through an RAFT (Reversible Addition-Fragmentation Chain Transfer) polymerization method. According to the method, a chain transfer reagent-RAFT reagent is used during synthesis of a macromolecular chain, and after the chain transfer reagent is added, the reaction rate can be effectively reduced, and gelation is avoided; the control on the molecular weight can be ensured; after the primary amine is added, a C-S bond in the RAFT reagent is converted into sulfydryl which is further oxidized into a dynamic disulfide bond in air, the molecular weight of the fracturing fluid is doubled, and the drag reduction performance of the fracturing fluid is effectively improved; after the reducing agent is added, the disulfide bond is broken, the molecular weight is rapidly reduced, and after the oxidizing agent is added, the molecular weight can be rapidly increased. The obtained linear drag reducer can reach the degradation rate of 87% or above, and has important significance on exploration and development of oil and gas resources.

The invention belongs to the technical field of polycarboxylate superplasticizers for concrete, and particularly relates to a sodium glutamate modified polycarboxylate superplasticizer and a preparation method thereof. The sodium glutamate modified polycarboxylate superplasticizer is prepared from a polyether monomer, acrylic acid, an initiator, a chain transfer agent, a reducing agent, sodium glutamate and water. By adding sodium glutamate, the molecular structure of the polycarboxylate superplasticizer is influenced, the water-reducing rate, slump holding time and neat paste fluidity of the polycarboxylate superplasticizer are improved, and the solubility of the polycarboxylate superplasticizer in water is improved, so that the dispersity, plasticity retaining property and the like of the polycarboxylate superplasticizer in concrete are improved; the working performance of the concrete is obviously improved.

The invention relates to the field of oilfield chemical fracturing, in particular to shape complementary type salt-resistant hydrophobic association polyacrylamide for fracturing oil extraction and a preparation method thereof, and the shape complementary type salt-resistant hydrophobic association polyacrylamide is prepared from pure water, acrylamide, acrylic acid, sodium hydroxide, urea, a first hydrophobic monomer, a second hydrophobic monomer, a salt-resistant monomer, a complexing agent, a chain transfer agent, an initiator, an oxidizing agent and a reducing agent. The preparation method comprises the following steps: firstly synthesizing a first hydrophobic monomer and a second hydrophobic monomer, then uniformly mixing and stirring pure water, acrylamide, acrylic acid, sodium hydroxide, urea, the first hydrophobic monomer, the second hydrophobic monomer and a salt-resistant monomer according to certain parts by mass, cooling, sequentially adding a complexing agent, a chain transfer agent, an initiator, an oxidant and a reducing agent, and uniformly stirring to obtain a finished product. After the reaction is finished, a rubber block is granulated, dried and ground, the shape complementary type salt-resistant hydrophobic association polyacrylamide for fracturing oil extraction is obtained, two hydrophobic monomers of the polyacrylamide have a shape complementary effect, and the viscosity of the polyacrylamide in saline water is effectively improved.

The invention discloses a super-retarding type polycarboxylic acid water reducing agent and a preparation method and application thereof, and belongs to the field of concrete water reducing agents. The preparation method comprises the following steps: taking acrylic acid AA, isobutenol polyoxyethylene ether HPEG and hydroxyethyl acrylate HEA as monomers, taking mercaptopropionic acid MPA as a chain transfer agent, taking hydrogen peroxide H2O2 and L-ascorbic acid Vc, and mixing in proportion to serve as an initiator; preparing a first and second monomer mixed solution; adding bottom water into the reaction kettle, and carrying out stepwise polymerization reaction; and cooling the reaction liquid, adjusting the pH value, filtering, and discharging to obtain the product. According to the invention, an ester functional monomer hydroxyethyl acrylate HEA is introduced, and a step-by-step polymerization technology is adopted to control the dispersion process of water reducing agent molecules on cement particles, so that the water reducing agent molecules continuously disperse the cement particles within a certain period of time; the problem that the slump loss is too fast due to long-time and long-distance transportation of concrete or transportation in high-temperature weather is effectively relieved.

The invention discloses a polypropylene composite material as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials, the polypropylene composite material comprises the following components in parts by weight: 100 parts of polypropylene resin, 14-32 parts of acrylate monomer, 0.14-0.32 part of chain transfer agent, 0.14-0.32 part of initiator, 0.9-11 parts of 3-methacryloyldopamine-maleic anhydride copolymer and 0.04-0.32 part of nucleating agent; the mass percentage content of 3-methacryloyl dopamine in the 3-methacryloyl dopamine-maleic anhydride copolymer is 5 to 25 percent. The polypropylene composite material has excellent coating adhesive force and aging resistance, is very suitable for preparing automobile parts, and is especially suitable for preparing automobile bumpers.

The invention belongs to the technical field of concrete, and particularly relates to a polycarboxylate superplasticizer and a preparation method thereof. The polycarboxylate superplasticizer is prepared from an unsaturated polyether macromonomer, an unsaturated acid monomer, an unsaturated carbonate monomer, an unsaturated amino monomer, an initiator, a reducing agent, a chain transfer agent, deionized water, a solubilizer and organic alcohol amine. Wherein the unsaturated carbonate monomer is allyl methyl carbonate, and the unsaturated amino monomer is 2-aminoethyl methacrylate hydrochloride. According to the invention, excellent water reducing effect and stable control capability on concrete slump are maintained, and micro-cracks can be effectively made up through a dual mechanism formed by carbonate release and CaCO3 precipitation in the early and later stages of concrete hardening.

The invention relates to a synthesis method of a polymer, in particular to a living polymerization method based on pulse type chain transfer. The polymerization method comprises chain transfer reaction stages and chain propagation reaction stages which are alternately carried out, and one chain propagation reaction stage and one chain transfer reaction stage which are adjacent form a reaction period; in the chain transfer reaction stage, the whole reaction system is dominated by the chain transfer reaction; in the chain growth reaction stage, the whole reaction system is dominated by the chain growth reaction of living polymerization; the living polymerization method further comprises a triggering condition which enables the whole reaction system to be switched between a chain propagation reaction stage and a chain transfer reaction stage. The triggering condition is a reaction condition capable of being accurately regulated and controlled or a chemical substance condition capable of being cleared or changed. The method provided by the invention can reduce the dosage of the active polymerization initiator and improve the controllability of the reaction system, and is especially suitable for preparing polymers with expected molecular weight distribution range or block polymers with expected sequence structures.

The invention relates to a dry-jet wet-spinning ultra-high-performance polyacrylonitrile-based carbon fiber and a preparation method thereof, and belongs to the technical field of carbon fibers. A preparation method of dry-jet wet-spinning ultra-high-performance polyacrylonitrile-based carbon fiber comprises the following steps: S1, mixing acrylonitrile, a comonomer, a chain transfer agent, an initiator and a solvent, carrying out polymerization reaction through a solvent dropwise addition method, and preparing a spinning solution; wherein the comonomers comprise a first comonomer, a second comonomer and a third comonomer; s2, the spinning solution is subjected to solidification, water washing, water drawing, oiling, drying and steam drawing, and precursor fibers are obtained; s3, the precursor fiber is sequentially subjected to pre-oxidation, low-temperature carbonization, high-temperature carbonization, graphitization, surface treatment, sizing and drying, and the ultra-high-performance polyacrylonitrile-based carbon fiber is prepared. Wherein the pre-oxidation adopts four-stage pre-oxidation treatment. The strength and modulus of the carbon fiber can be effectively and synergistically optimized, and the carbon fiber with high strength and high modulus is prepared.

A RAFT agent for photo-controlled (iniferter) polymerization, preparation method therefor, and applications thereof. The RAFT agent has a structure represented by the general formula:wherein R2 and R3 are each hydrogen, and R1 is methyl. The RAFT agent is structurally and chemically stable, simple to synthesize, and enables rapid photo-controlled polymerization under blue light. It has been demonstrated that when using this RAFT agent for polymerization, the reaction time is reduced to just a few minutes, achieving a high conversion rate for acrylate and acrylamide monomers. Additionally, polymerization with the RAFT agent does not require the introduction of additional initiators or photocatalysts, as the RAFT agent itself can facilitate chain initiation and chain transfer under blue light. Compared to other photo-controlled polymerization methods, the apparent propagation rate is faster, and no additional impurities are introduced into the final product, thereby not affecting the color and performance of the polymer.

The invention belongs to the technical field of polyurethane, and particularly relates to multi-element synergistic flame-retardant polymer polyol and a preparation method thereof. The flame-retardant polyether polyol is prepared from phosphorus-halogen mixed flame-retardant basic polyether polyol, a halogen-containing flame-retardant vinyl unsaturated monomer, a silicon-containing flame-retardant vinyl unsaturated monomer, a nitrogen-containing modified polyether dispersant, styrene, acrylonitrile, an initiator and a chain transfer agent through reaction. The halogen-containing monomer introduced into the POP polymerization monomer directly participates in free polymerization, and cooperates with the flame-retardant elements in the basic polyether, so that the content of the flame-retardant elements in the POP can be effectively increased, and the flame retardance is improved. A vinyl silicon structure is added in a POP polymeric monomer, and a silicon element is introduced into a molecular chain, so that the flame retardance is improved, the hydrophobicity of POP can be improved, and the viscosity of the composite material is reduced. The macromolecular nitrogen-containing dispersing agent forms a nitrogen-phosphorus-bromine ternary synergistic flame-retardant system by adopting a DMC catalytic process and a polyurethane synthesis technology, so that the flame retardance of POP is further improved.

The invention relates to the technical field of concrete admixtures in building materials, in particular to a viscosity reduction type polycarboxylic acid water reducer suitable for high-strength concrete and a preparation method of the viscosity reduction type polycarboxylic acid water reducer. The hydrophobic modified unsaturated double-chain polyether macromonomer is prepared from the following components in parts by mass: 20 to 30 parts of unsaturated acid, 200 to 300 parts of hydrophobic modified unsaturated double-chain polyether macromonomer, 10 to 15 parts of phosphate monomer, 2 to 4 parts of oxidizing agent, 1 to 2 parts of reducing agent, 1 to 2 parts of chain transfer agent, 5 to 10 parts of neutralizing agent and 120 to 180 parts of water. According to the invention, the polyether chain can unfold in a pore solution, the steric hindrance effect is further enhanced, cement particles are ensured to be effectively dispersed in a compact space, and meanwhile, the hydrophobic part of the side chain can effectively reduce the surface tension of the pore solution, so that the condition of overhigh viscosity is avoided, and the flowability and constructability of the concrete are improved.

The invention belongs to the field of membrane materials, and particularly relates to a polyether-based block copolymer and a preparation method and carbon capture application thereof. According to the invention, dichloromethane is taken as a solvent, trifluoromethanesulfonic acid is taken as an initiator, and in the presence of a chain transfer agent ethylene glycol, 1, 3-dioxolane is subjected to cationic ring-opening polymerization to generate PDXL (HO-PDXL-OH) of which two terminal groups are hydroxyl groups. Further, N, N-dimethylformamide is used as a solvent, dibutyltin dilaurate is used as a catalyst, and HO-PDXL-OH and diphenylmethane diisocyanate are subjected to polycondensation to synthesize block copolymer polyurethane (PU). The polyether-based segmented copolymer prepared by the preparation method disclosed by the invention is used as a gas separation membrane material and has relatively high CO2 capture performance, and the CO2 separation performance of the polyether-based segmented copolymer is superior to that of other polyether-based membrane materials and is close to the Robeson upper limit.

The invention relates to a catalytic system for preparing a cycloolefin copolymer and application. The catalytic system comprises a main catalyst, a catalyst promoter and a chain transfer agent, the main catalyst is a silane-bridged fluorenyl amino dimethyl titanium complex, a silane-bridged fluorenyl amino dimethyl zirconium complex, a silane-bridged fluorenyl amino dimethyl hafnium complex or a silane-bridged fluorenyl amino hafnium dichloride complex; the auxiliary catalyst is a silane-bridged fluorenyl amino dimethyl titanium complex, a silane-bridged fluorenyl amino dimethyl zirconium complex, a silane-bridged fluorenyl amino dimethyl hafnium complex or a silane-bridged fluorenyl amino dimethyl hafnium complex; the cocatalyst is an aluminum compound or a boron compound; the chain transfer agent is more than one of second main / subgroup metal complexes; during application, the catalytic system is adopted, and cycloolefin and non-cyclic olefin are subjected to a copolymerization reaction under the catalytic action of the catalytic system to prepare the cycloolefin copolymer. According to the catalytic system disclosed by the invention, the consumption of expensive silane-bridged metal complexes is remarkably reduced, and powerful regulation and control on the molecular weight of a polymer are realized while high polymerization activity is maintained; the prepared cycloolefin copolymer has the advantages of adjustable molecular weight wide range, narrow molecular weight distribution, and controllable cycloolefin insertion rate and glass transition temperature.

The invention relates to the technical field of concrete admixtures, in particular to a sulfate-resistant polycarboxylate superplasticizer and a preparation method thereof. The sulfate-resistant polycarboxylate superplasticizer is prepared by copolymerization reaction of ethylene glycol monovinyl polyglycol ether, first unsaturated carboxylic acid, unsaturated phosphate and a functional monomer XS under the action of an initiator and a chain transfer agent. The sulfate-resistant polycarboxylate superplasticizer provided by the invention has excellent sulfate resistance and good working performance. A normal-temperature free radical solution copolymerization synthesis technology is adopted for synthesis, heating is not needed in the preparation process, preparation steps are simple and convenient, raw materials are easy to obtain, equipment is conventional, and actual industrial application requirements can be met.

The invention relates to a mud-resistant polycarboxylic acid water reducing agent and a preparation method thereof, and the mud-resistant polycarboxylic acid water reducing agent is prepared from the following raw materials in parts by weight: 90-260 parts of allyl-terminated polyether monomer; 20 to 32 parts of unsaturated acid monomer; 8-15 parts of an unsaturated ester monomer; 4-8 parts of a quaternary ammonium salt compound; 1.5 to 3.0 parts of an oxidizing agent; 0.2 to 0.4 part of a reducing agent; 0.8 to 1.5 parts of a chain transfer agent; and water; wherein the allyl-terminated polyether monomer is prepared from the following raw materials: unsaturated alcohol, an allyl compound and a basic catalyst. The polycarboxylate superplasticizer prepared by the method disclosed by the invention has the advantages of low mixing amount, high water reduction, good workability, low mixing amount sensitivity, excellent mud resistance, capability of remarkably improving the dispersion and adsorption performance of concrete, wide application range of mud content in sand and gravel materials and the like.

Disclosed in the present invention is a composition for preparing a vinyl block copolymer, the composition comprising: a first monomer ethylene, a second monomer a C3-C20 α-olefin and at least one regulation monomer, the regulation monomer being an olefin or a substituted olefin with the C atom number greater than 3, or styrene / a styrene derivative, and in the same composition, the second monomer being different from the regulation monomer. The composition is catalyzed by a main catalyst and a co-catalyst to obtain the vinyl block copolymer, wherein the main catalyst is a complex L-MR1R2R3 that contains three substituents and that is formed by an IVB-group metal and a monoanionic ligand, and the co-catalyst includes alkyl aluminum, polymerized or oligomerized aluminoxane, a neutral Lewis acid, a non-polymer, a non-coordinated ionic compound, or a mixture of two or more described above. Provided in the present invention is a composition capable of obtaining a lower-olefin block copolymer, the composition can obtain a lower-olefin block copolymer without the need of replenishing monomers or adding a chain transfer reagent for polymerization during polymerization processes, so that a production process is simple and involves low cost.

The invention discloses a viscosity reduction type concrete admixture and a preparation method thereof, and belongs to the technical field of concrete admixtures. The admixture comprises a viscosity reduction type polycarboxylic acid water reducing agent, a hydrophobic surfactant, an air entraining agent, a defoaming agent, a retarder and water, wherein the viscosity reduction type polycarboxylic acid water reducing agent is prepared from a polyether monomer, unsaturated acid, a viscosity reduction functional monomer, an oxidizing agent, a reducing agent, a chain transfer agent, a neutralizing agent, a catalyst and deionized water. The viscosity reduction type polycarboxylic acid water reducer added in the admixture effectively reduces the HLB (hydrophile-lipophile balance) value of the surface of cement paste through the polymerization of phosphate groups in the viscosity reduction functional monomer, improves the flowability of concrete, and realizes the viscosity reduction effect. The mixing amount level of the admixture is 1.0-1.8%, and the admixture has the characteristics of low mixing amount, environment-friendly preparation process and excellent viscosity reduction effect, and has no negative influence on indexes such as concrete strength and the like.