33results about How to "Molecular weight distribution index is small" patented technology

Biocompatible monodisperse nanopolymer carrier and methods for its preparation and drug loading. First, an amphiphilic block copolymer with a small molecular weight distribution index was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization, in which the hydrophilic segment was methacryloyloxyethylphosphorylcholine (MPC ), and the hydrophobic segment is n-butyl methacrylate (BMA). Then, the above-mentioned amphiphilic block copolymer is used to prepare nanometer polymer micelles by a solvent evaporation method, and drugs are encapsulated in the micelles by physical action to obtain a monodisperse nanometer polymer drug-carrying system with good biocompatibility.

The invention provides a double-metal cyanide catalyst for copolymerization of carbon dioxide and epoxide. The structural formula is M1a [M2 (CN) bLc] dXi, and the catalyst is obtained by mixing a complex M1LX of metal M1, cyanide of metal M2 and metal salt M1eXf and performing reaction under mechanical ball milling, wherein M1LX is a compound with a structure as shown in the following formula (II) which is described in the specification, M2 is selected from one of Co<2+>, Co<3+>, Fe<2+>, Fe<3+>, Cd<2+> and Mn<3+>, and X is selected from one or more of F<->, Cl<->, Br<->, I<->, NO3<->, SO4<2->or organic carboxylate anions. The preparation method of the catalyst is simple, convenient and green, the catalyst is high in catalytic efficiency, good in activity and good in stability, and in a carbon dioxide / epoxide copolymerization reaction, higher catalytic activity and higher selectivity of a polymer product and polycarbonate chain links on a polymer main chain can be embodied in a polymerization reaction under the conditions of relatively lower catalyst concentration and higher initiator concentration.

The invention relates to a method for preparing micromolecule pectin, belonging to the production technology of macromolecule pectin. The invention provides a method for preparing micromolecule pectin of which the weight-average molecular weight is 10000-30000, the micromolecule pectin is obtained by degrading natural pectin in an acid solution system at the temperature of 55-110DEG C, and the acid solution system is methanoic acid, acetic acid, sulfuric acid or hydrochloric acid aqueous solution. The reaction yield can be 5-30%, the pectin esterification degree is not lowered, and the structure of branched chain heteropolysaccharide is not changed; and the obtained pectin degree of index (PDI) is controlled to 1.6-2.5, i.e. the molecular weight distribution index is lower. The pectin of which the molecular weight is 10000-30000 can serve as a carrier for the in-vivo kidney to excrete and can serve as a polymer drug carrier for intravenous injection.

The invention provides a preparation method of medical biodegradable polymer material polylactate geycollic acid (PLGA). A mass polymerization method is adopted for manufacturing the polylactate geycollic acid (PLGA), the production technology is simple, conditions needed by the reaction are low, the reaction speed is high, and the reaction time is short; a catalytic system adopting an organic metal compound as a main catalyst and adopting a substance containing reactive hydrogen as an initiator is adopted as an efficient catalytic system, the reaction time is shorter compared with a single catalyst, the weight-average molecular weight of the product is adjustable, the lowest molecular weight distribution index can reach 1.40, the catalytic activity is high, and the PLGA is non-toxic basically; the reaction product is precipitated three times, unreacted monomers and low-molecular-weight by-products can be removed, the molecular weight distribution index is lowered, and the product purity is improved.

The invention discloses an aluminum trichloride catalyst system and a method for producing low-molecular-weight polyisobutene with the same and relates to a catalyst system and a method for producing polyisobutene with the same. The aluminum trichloride catalyst system is prepared from raw materials in parts by weight as follows: 5-50 parts of anhydrous aluminium trichloride powder and 50-95 parts of an isobutylene oligomer. The aluminum trichloride catalyst system is free of foreign organic matters and environmental pollution; the aluminum trichloride catalyst system has high adaptability to the raw materials and is used for polymerization production of the low-molecular-weight polyisobutene from an isobutylene-containing mixed C4 raw material, the required low-molecular-weight polyisobutene can be obtained, the low-molecular-weight polyisobutene product is high in purity and free of other organic matter residues, and an isobutylene oligomer byproduct can also be obtained.

A fractionators narrowing polyester polyol molecular weight distribution is disclosed. A wastewater collection tank (7) is installed adjacent to a polyester reaction vessel (2), also a reflux pipe is connected between the upper end of the polyester reaction vessel (2) and the lower end of a dephlegmator (4), the reflux-pipe segment is provided with a U-shaped pipe (5), the communication bottom end of the U-shaped pipe (5) is connected with the wastewater collection tank (7), and the bottom of a condenser is connected with the wastewater collection tank (7); the dephlegmator (4) is connected with the condenser (6), the polyester reaction vessel (2) is connected with the dephlegmator (4), a return valve is arranged at the pipeline connecting the U-shaped pipe (5) with the polyester reaction vessel (2). The product quality is improved, alcohol removal labor hour is saved, the processing time of 6 KL of the raw material is shortened within 1 h from original 3-5 h, micromolecule alcohols are rapidly efficiently removed, polyester polyol molecular weight distribution is properly narrowed, and the molecular weight distribution index is relatively small. The cobalt-platinum colour is relatively low, and the acid value is relatively low and is within 0.1 mg KOH / g.

The invention relates to the field of olefin polymerization, and particularly provides polypropylene, a preparation method and applications thereof, wherein the polypropylene has a melt flow index MFRof more than 30 g / 10 min, has an isotactic index of 96-99.5 wt%, and has a molecular weight distribution index MW / Mn of 3-5.5. The preparation method comprises: polymerizing propylene in the presenceof a catalyst under an olefin polymerization condition to obtain a polypropylene product, wherein the catalyst contains a catalyst component, an alkyl aluminum compound, and optionally an external electron donor, the catalyst component contains the product obtained by carrying out a reaction on a magnesium source, a titanium source and an internal electron donor, the internal electron donor contains a phosphate compound and a diether compound, and the phosphorus content (calculated as the phosphorus element) in the catalyst component is not more than 0.06 wt%. According to the present invention, the polypropylene integrates characteristics of high isotactic index, high melt flow index and narrow molecular weight distribution.

The invention relates to an imitated nylon differential fiber of dyeable polypropylene fiber for dyeing, which comprises: 80 to 90 percent of polypropylene, 9 to 11 percent of dyeable master batch, 0.3 to 0.7 percent of cooling auxiliary agent and 4.0 to 5.0 percent of polyethylene. The fiber has the advantages that: firstly, the polypropylene fiber has the flexibility, tensile property and elasticity as nylon through modifying the polypropylene fiber; and secondly, the dyeability of the modified polypropylene fiber is realized.

The invention belongs to the field of chemical engineering, and particularly provides a method for preparing a double metal cyanide catalyst. The method comprises the following steps of: mixing water soluble metal salt and water soluble metal cyanide, and then carrying out mechanical ball milling to ensure that the water soluble metal salt and the water soluble metal cyanide undergo a mechanical chemical reaction; and removing the product, cleaning with a mixed solution, separating the precipitate, and drying the precipitate under a vacuum condition to obtain the double metal cyanide catalyst. The method is easy, can be used for synthesizing the double metal cyanide catalyst under a mechanical ball milling condition. The process is simple, consumes less time, has low usage of organic compounding ingredient and low cost, can greatly save raw materials and reduce energy consumption, and is suitable for industrial production and application.

The invention discloses a preparation method of an acrylonitrile copolymer spinning solution with low molecular weight distribution. According to the invention, in a solution polymerization process between acrylonitrile monomers and comonomers, the weight-average molecular weight and number-average molecular weight of a copolymer are regulated in a continuous or intermittent cooling manner so as to reduce the molecular weight distribution index of the copolymer. Compared with other methods, the preparation method is simple and feasible and is stronger in process operability, the molecular weight distribution index of an acrylonitrile copolymer obtained according to the method can be controlled to be 2.3-2.8, and an acrylonitrile copolymer solution can be used as a high-performance polyacrylonitrile-based carbon fiber spinning solution after residual monomers and air bubbles are removed.

The invention discloses modified (methyl) acrylate resin. The resin contains a (methyl) acrylate chain link, an unsaturated double bond and carboxylic group, an unsaturated double bond and epoxy group and an organic silicon group containing double bonds. The modified (methyl) acrylate resin can be solidified through various methods, has the characteristics of high hardness, high toughness, no adhesion, strong adhering force, good wear resistance and the like, and can be applied to fields such as coating, ink and adhesive. The invention further relates to a preparation method of the material.

The invention discloses a reversible addition-fragmentation chain transfer free radical polymerization method, wherein characterized in that, microwave radiation heating can be used for polymerization, and it is possible not to use initiating agent . The invention can greatly increase polymerization speed, andconveniently control molecular weight of polymerization product.