219results about How to "Control molecular weight" patented technology

The invention discloses a bis (imino) pyridine iron olefin polymerization catalyst and a preparation method and application thereof. The catalyst is a novel bis(imino)pyridine iron complex with the asymmetric substitution of position 2 and 6 of an aromatic ring; and the structural formula of the catalyst is shown in formula (I), wherein X is halogen, R1 is alkyl, and R2 is the alkyl or oxyl. The catalyst can be obtained through a Friedel-Crafts reaction, a ketoamine condensation reaction and a coordination reaction. The preparation method is simple, and raw materials are cheap. The catalyst can catalyze the polymerization of ethylene under the activation of MAO to prepare polyethylene with high molecular weight and wide distribution.

The invention provides a derivate of low molecular weight fucosylated glycosaminoglycan (dLFG) and a medical composition containing the dLFG or pharmaceutically acceptable salt and application of the dLFG and the medical composition for preparing medicines for treating thrombotic diseases.

The invention discloses fluorosilicone modified acrylic resin as well as a preparation method and an application thereof. The fluorine-silicon modified acrylic resin is prepared from the following components: methacrylate monomers, fluorine-containing acrylate monomers, acrylate-based silicone oil, allyl silicone oil, a polymerized active silane coupling agent, methacrylic acid, hydroxyl-containing active crosslinking monomers, glycidyl methacrylate, trimethylolpropane trimethacrylate, an initiator, a chain transfer agent and a solvent. The fluorine-containing acrylate monomer is composed of aC2-C3 short-chain fluorine-containing alkyl acrylate monomer and a C10-C12 long-chain fluorine-containing alkyl acrylate monomer. The fluorine-silicon modified acrylic resin prepared by the inventionhas the characteristic of high low viscosity, is convenient to construct and use, and reduces the generation of VOC. The coating prepared from the modified acrylic resin has the characteristics of high impact-resistant self-repairing function, icing prevention, low surface energy, hydrophobicity, oleophobicity, stain resistance, high and low temperature resistance and the like.

The present invention provides a novel narrow distribution dendrimer-like star polymer having a controlled molecular structure, and a method capable of easily producing the star polymer.

Disclosed is a polymer comprising a core portion and an arm portion, wherein the arm portion includes a first generation composed of a polymer chain and a second generation composed of a polymer chain formed at the outer shell of the first generation, the number of arms of the second generation is larger than the number of arms of the first generation, the first generation composed of the polymer chain is a polymer chain derived from a monomer having a polymerizable double bond, and the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), (Mw/Mn), of the star polymer is within a range from 1.001 to 2.50. A compound containing a functional group capable of reacting with an anion, which serves as a core portion, is reacted with a polymer chain containing two or more functional groups and an anion end which serves as an arm portion.

The invention relates to a preparation method for a low-formaldehyde melamine resin retanning agent. The method comprises the following steps: preparation of a terminated modified monomer from a phenolic monomer with functionality of 1 to 6; synthesis of (hydroxymethyl)melamine; termination condensation of the terminated modified monomer and (hydroxymethyl)melamine; and preparation of the retanning agent. The retanning agent prepared in the invention has reasonable melamine resin molecular weight and extremely low free formaldehyde content and is applicable to leather production; and the content of free formaldehyde in produced leather reaches the standard, and the free formaldehyde content is lower than 75 ppm, reaching European standards Class B.

The invention discloses a restructuring animal yarn-RGD merged protein and its biosynthesis method, the amino acid sequence of restructuring animal yarn-RGD merged protein contains sequence which roots from nature animal yarn protein and sequence contains short peptide RGD, it also contains the biosynthesis method of this merged protein. The restructuring animal yarn-RGD merged protein of this invention has structure and function of nature animal yarn protein as well as cell adhesive activity, it also provides a method which uses gene recombination and fermentation technique to synthesize simulated nature animal yarn protein, the merged protein can be used to surface finish of medical material, it can be used as degradable medical biological material after processing and applied in organization project.

The invention discloses hyperbranched polyurethane containing epoxy groups as well as a preparation method and application thereof. According to the invention, by controlling the mole ratio of diisocyanate and trihydric alcohol, a reaction medium, adding amount of a matter containing epoxy groups, reaction temperature and reaction time, the hyperbranched polyurethane with the weight-average molecular weight of 25,000-10,0000 and 8-40 epoxy groups is obtained. The prepared hyperbranched polyurethane containing epoxy groups is wide in raw material source, and commercialized; a polymerization method is mature and the preparation process is simple; the hyperbranched polyurethane containing epoxy groups is easy to store. In addition, the hyperbranched polyurethane containing epoxy groups can be used as an active modifier for a thermosetting resin prepolymer.

The invention relates to a heterochain polymer chiral stationary phase and process for preparing same, wherein the heterochain polymer chiral stationary phase is formed by carriers and chiral macromolecules through the connection of polyamide bonds or carbamide bonds, the carrier being 3-amino propyl silica gel. The obtained chiral stationary phase has good chiral identification capability.

The invention discloses an ester-ether mixed structure mud-resistant polycarboxylate superplasticizer and a preparation method thereof. The superplasticizer is prepared from the following components in parts by weight: 180-220 parts of a polyether macromonomer, 140-180 parts of an esterification macromonomer, 30-40 parts of an unsaturated acid, 1-5 parts of an anionic monomer, 2-4 parts of an oxidant, 0.5-2.5 parts of tartaric acid, 0.5-1.5 parts of a chain transferring agent, 400-500 parts of deionized water and 140-160 parts of 32% sodium hydroxide. The ester-ether mixed structure mud-resistant polycarboxylate superplasticizer has the advantages of being low in admixture amount, high in water reduction rate and good in mud resistance, and even in case of a relatively high mud content ofaggregate, a relatively high water reduction rate can be maintained for the superplasticizer. Meanwhile, the superplasticizer is simple in process, can be prepared under a normal-temperature condition, and is easy in reaction condition control, low in energy consumption and free of pollution.

The invention provides terminal alkenyl nonsaturated polyether shown in a formula (1), and the invention also provides a purpose of the terminal alkenyl nonsaturated polyether. According to the provided terminal alkenyl nonsaturated polyether, a polyether chain segment can be adjusted through different structural units, so that dispersion effect of a prepared water reducer on concrete is increased, and water-reducing rate of a polycarboxylic acid water reducer and slump constant are obviously increased. The preparation method has the advantages of simple operation, mild condition and easy industrial application.

The invention discloses a method for synthesizing high molecular weight instant anionic polyacrylamide, which is characterized in that: an alkaline hydrolysis method is adopted, and comprises the following steps of: preparing aqueous solution of acrylamide monomer from the acrylamide monomer by using deionized water, adding a hydrolytic agent, a composite initiator and an auxiliary agent, regulating the pH value to be between 8.5 and 12, introducing nitrogen, expelling oxygen and sealing a system at the temperature of between 10 and 25 DEG C, polymerizing under the heat insulation condition, and hydrolyzing, crushing, drying and grinding to obtain instant anionic polyacrylamide solid powder with the viscosity-average molecular weight of 15,000,000 to 21,000,000 and the dissolution time of shorter than 0.5 hour. A novel coordination agent and a novel pH value regulator are adopted, the method is easy and convenient to operate, the initiation speed of the monomer is high, the dissolution speed of a product is high, the reaction rate and the molecular weight of the product are controllable, the method is suitable for production on different scales, and the product is suitable for industries such as papermaking dispersants, tertiary oil recovery, beneficiation, sewage treatment and the like.

The invention relates to a method for synthesizing polyaspartic acid by maleic anhydride and ammonia gas. The method comprises the following steps: performing substitution reaction of molten maleic anhydride and ammonia gas in a closed reactor and absorbing the residual gas after the completion of the substitution reaction; adding sodium hydrate solution into the reacted maleic anhydride and ammonia gas to perform neutrallzation reaction, so as to obtain a mixture of maleamic acid sodium and maleamic acid ammonium; directly heating the product in the closed reactor and performing condensation polymerization by stirring; steaming and drying the moisture after the completion of the condensation polymerization, so as to obtain the polysuccinimide solid; adding water in another reaction kettle and starting stirring; then adding the polysuccinimide solid into the reaction kettle and slowly adding sodium hydrate solution and heating to perform hydrolysis reaction, so as to obtain the polyaspartic acid solution. According to the method for synthesizing polyaspartic acid by maleic anhydride and ammonia gas, the production process is simplified and the polyaspartic acid prepared according to the method has a weight-average molecular weight of 2000-15000 and a molecular weight distribution index of 1.5-1.65, so that molecular weight requirements of various application domains are met and environment-friendly production process is realized.

The invention belongs to the technical field of preparation of building material admixtures, and particularly relates to an anti-flocculating agent, a preparation method and application thereof. According to the invention, when the anti-flocculating agentis used in concrete, the problems that the viscosity of the concrete becomes large and the fluidity becomes poor after a flocculating agent is added into the concrete can be solved, the addition of the anti-flocculating agenthas no influence on the performance of the concrete, and in the use process, crystals cannot be separated out in the using process, the water solubility is good, and the structure is stable; and when silt in concrete is settled by a flocculating agent, the flocculating agent in the water phase of the concrete can be removed by the anti-flocculating agent, so that the problem that the flocculating agent is unfavorable for the performance of the concrete is fundamentally solved.

The invention relates to the technical field of aqueous polyurethane dispersions, in particular to an aqueous dispersion of polyurethane or polyurethane urea as well as a preparation method and an application thereof. The polyurethane or polyurethane urea is a reaction product prepared from raw materials comprising the following components: a) a polyol having Mn being greater than or equal to 1000and a functionality of 2-4; b) isocyanate having at least two isocyanate groups, optionally, c) a monofunctional nonionic hydrophilic compound containing at least one NCO reactive functional group, d) a hydrophilic compound containing one or more of an ionic group, a latent ionic group and a nonionic group and containing 2-3 NCO reactive functional groups, e) a hydroxyl fatty acid with a long carbon chain, f) a small molecular end-capping agent containing a single amino group, and optionally g) a low molecular compound containing 2 or more NCO reactive amino groups. The aqueous dispersion disclosed by the invention not only can ensure the softness of the resin, but also can improve the adhesive force of the aqueous slurry on the nylon fabric.

The invention relates to an environmentally-friendly cross-linked acrylate polymer emulsion and a preparation method thereof. The emulsion consists of six main components through semicontinuous seeded emulsion polymerization, is fine and smooth in appearance and is a blue-fluorescent semitransparent emulsion, a pH value is 7.5+/-0.5, the solid content is 30-50%, the emulsion particle diameter is 50-100 nanometers, and the polymer emulsion has good film-forming property and adhesion after film forming at the 80 DEG C temperature. The environmentally-friendly cross-linked acrylate polymer emulsion has the advantages that due to the fact that an amino acid based anionic surface active agent and an alkyl polyglucoside non-ionic surface active agent both have excellent biodegradability and environmental protection effect and are used for replacing commonly-used alkylphenol polyoxyethylene ether and an alkylbenzene sulfonate surface active agent having poor biodegradability, the environmentally-friendly cross-linked acrylate polymer emulsion is more environmentally-friendly, and the demand for the performances of the emulsion is met.

The invention discloses a modified urethane acrylate copolymer. The modified urethane acrylate copolymer is prepared from 16.1 to 50.9 parts by mass of polyisocyanate, 15.4 to 40.2 parts by weight of polyether polyol, 0. 01 to 0.09 parts by weight of a catalyst, 3.1 to 11.6 parts by weight of carboxylated diol, 5.3 to 20.8 parts by weight of epoxy resin, 0.1 to 0.5 parts by weight of a polymerization inhibitor, 10.7 to 35.5 parts by weight of hydroxyl group-containing acrylate, and 10 to 80 parts by weight of a solvent. The polyisocyanate is a mixture of one or more of hexamethylene diisocyanate, tolylene diisocyanate, 1, 6-hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and polymethylene polyphenyl polyisocyanate. The modified urethane acrylate copolymer has the advantages of simple operation and short production period. The modified urethane acrylate copolymer has the advantages of adjustable acid value, good heat resistance, strong corrosion resistance, good adhesion to the substrate and stable performance. The prepared photoresist has good comprehensive performances and is easy to promote and use.

The present invention relates to hydroxy terminated polypropylene in the structure as shown and its preparation process. The catalyst system comprising metallocene and alkyl aluminoxane catalyzes propylene polymerization reaction, dry air or oxygen is then introduced into the reacted system, and hydrogen perosxide and alkali hydroxide aqua are finally added for treating to obtain polypropylene with one hydroxy radical in one end of the macro molecular chain. The polymer of the present invention has high terminated hydroxy function degree not lower than 0.8, high isotactic configuration, high adjustable molecular weight, narrow molecular weight distribution, simple preparation process, and other advantages.

The invention relates to a weather-resistant pearlescent pigment, and a preparation method thereof. The method comprises: firstly, depositing a liquid phase on the surface of a pearlescent pigment to form an inorganic coating layer through hydrolyzing a metal salt (such as aluminum salt, cerium salt); then, further performing grafting on the surface of the obtained pearlescent material by adopting a silane coupling agent containing an amino functional group and bromo-acylhalide (such as bromo-carboxylic acid) to prepare the pearlescent pigment containing an initiating group for atom transfer radical polymerization; and finally, forming a three-dimensional organic coating layer on the surface of the pearlescent pigment by initiating an unsaturated monomer containing an epoxy group. According to the method, a requirement of weather resistance for the pearlescent pigment is met, and powder comprising a polymer with the proper molecular weight is obtained by effectively adjusting the degree of polymerization of the monomer. The pearlescent pigment has excellent dispersibility and stability in application to paint, and the modified powder can reach an effect of act according to actual circumstances during application to paint.