52results about How to "Molecular weight regulation" patented technology

The invention discloses a preparation method for a polycarboxylic acid series comb-shaped surface active agent, which comprises the following steps of: mixing two comonomers, an initiator, a chain transfer agent and a solvent under the protection of nitrogen, heating to a reacting temperature for polymerization to obtain an intermediate polymer; adding a graft compound, a catalytic agent and a dissolvant into the intermediate polymer, carrying out graft reaction at graft temperature, decompressing and removing part of solvent in a reaction system after reaction, and then precipitating the product with a precipitator; dissolving filter cakes with the solvent; precipitating the dissolved solution with the precipitator again, dissolving repeatedly, precipitating again and then refining, and finally decompressing and drying the product to the constant weight. The preparation method has the advantages of reasonable technology, simple operation, low preparation cost, mild reacting conditions and good product quality.

A synthetic method of a styrene / maleic anhydride alternating copolymer with low molecular weight belongs to the field of macromolecular precipitation polymerization. Media and chain transfer agents used in the existing methods for preparing styrene / maleic anhydride copolymers by precipitation polymerization have disadvantages. In the synthetic method, the styrene / maleic anhydride alternating copolymer is prepared by taking a mixed solvent of organic acid alkyl ester and alkane as a reaction medium for the precipitation polymerization, alpha-methylstyrene or vinyl acetate as a molecular weight regulator and organic peroxide or an azo compound as an initiator for initiating a copolymerization reaction between styrene monomers and styrene. The synthetic method has simple process, the synthesized copolymer has good properties, and the method has the advantages of being economical, environment-friendly and the like.

The invention discloses injectable high-strength and temperature-sensitive modified chitin-based hydrogel as well as a preparation method and application thereof. The gel is characterized in that a temperature-sensitive chitin derivative is dissolved into a water system at low temperature and a crosslinking agent or a photoinitiator is introduced to form an injectable hydrogel precursor solution with good flowability; after the injectable hydrogel precursor solution is injected into a body, the injectable high-strength hydrogel is formed through spontaneous chemical crosslinking or light illumination crosslinking under physiological conditions. The hydrogel disclosed by the invention has abundant precursor material sources and is easy to prepare; the photoinitiator or the crosslinking agent, which has relatively good solubility and very low toxicity in water, is used. The temperature-sensitive chitin derivative is utilized and can be physically cross-linked and molded under the physiological conditions and is further subjected to chemical crosslinking or photocrosslinking to prepare the injectable high-strength hydrogel and the injectable high-strength hydrogel does not need to besubjected to any post-treatment. Furthermore, the hydrogel has biodegradability and can be widely used for fields including biomedical materials, tissue engineering technologies and the like.

The invention discloses a method for preparing a star-like waterborne polyurethane associated-type thickening agent. The method comprises the following steps of: in the presence of an inert gas, adding dehydrated polyethylene glycol to react with isocyanate so as to prepare a prepolymer, performing semi-blocking by using long-chain alkanol, performing chain extension by using a chain extension agent of a polyhydric alcohol structure, and drying after the opeation is completed, thereby obtaining the star-like waterborne polyurethane associated type thickening agent. The star-like waterborne polyurethane associated type thickening agent synthesized by using the method has multiple hydrophobic long chains, is relatively large in molecular weight, can form a relatively complete and stable hydrophobic associated network structure in a water phase or emulsion system, and is relatively good in thickening property and stability. The star-like waterborne polyurethane associated-type thickening agent synthesized by using the method is very good in thickening effect, is capable of effectively increasing the viscosity of an emulsion with a relatively small use amount, and moreover has the characteristics of being high in viscosity under the action of small shearing force and low in construction viscosity under the action of large shearing force.

The invention discloses a dual-component emulsion polyacrylate pressure sensitive adhesive and a preparation method and application thereof and belongs to the field of functional high-polymer materials. The initial adhesive force, the continuous adhesive force, the stripping strength and other indexes of the obtained dual-component emulsion polyacrylate pressure-sensitive adhesive are excellent, and particularly the stripping strength of the dual-component emulsion polyacrylate pressure-sensitive adhesive makes greater breakthrough compared with other common pressure-sensitive adhesives. According to different applications, adjustment of mechanical properties can be achieved, and the requirements of various using ranges are met. The dual-component emulsion polyacrylate pressure-sensitive adhesive can be applied to adhesive tape, label paper, protective films, posters capable of being pasted and torn off, medical supplies and the like. According to different applications, by adjusting the weight ratio of a component I and a component II, different times when the component I is added into the component II, the chain transferring agent using amount of the two components and the varieties of the functional nonomers and changing the adding amount, outstanding practical performance is achieved. The pressure-sensitive adhesive can guarantee high stripping strength, balance of the initial adhesive force, the cohesive force and the stripping force is achieved, comprehensive performance of the pressure-sensitive adhesive is greatly improved, and high market practicability is achieved.

The invention relates to a high-solid chrome-free acrylic polyurethane finish paint consisting of two components A and B which are mixed together according to a ratio of 100:25. The component A comprises the following components in parts by weight: 50-65 parts of self-made tert-carbonic glycidyl ester modified hydroxylated acrylic resin (with 75 mass percent of solids), 10-20 parts of a color filler, 10-20 parts of a chrome-free anticorrosive pigment, 0.5-1.5 parts of an anti-setting agent BE-828, 0.5-1.5 parts of a dispersant, 0.3-1.0 part of a defoaming agent, 0.5-2.5 parts of an anti-sagging agent, 0.3-0.5 part of a leveling agent and 5-10 parts of a solvent. The component B comprises the following components in parts by weight: 50-70 parts of fat diisocyanate and 30-50 parts of butyl acetate. The high-solid chrome-free acrylic polyurethane finish paint disclosed by the invention has relatively high requirements for overall properties including weather resistance, fullness, salt fog resistance, adhesive force, chemical resistance and the like.

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 a gas-phase bulk polymerization method of a polyolefin alloy, in particular a polybutene alloy material. The method is characterized by (1) adopting a continuous or batch polymerization process; (2) performing gas phase polymerization of the polybutene alloy material in a single gas phase reactor or two or more gas phase reactors which are connected in series; and (3) respectively implementing homopolymerization of two monomers in two stages. The method adopts a single heterogeneous Ziegler-Natta catalyst which has multiple active centers and good hydrogen sensitivity to catalyze stage-by-stage polymerization of butene-1 and propylene, so that the polybutene alloy material which is less in catalyst residue and good in particle shape, does not have agglomerates and has a core-shell structure can be obtained. The prepared polybutene alloy material comprises the following components in percentage by mass: 10-99% of polybutene-1, 1-80% of polypropylene and 0.01-10% of butene-1-propylene copolymer, and can be used for replacing part of polyethylene and polypropylene in use.

The present invention relates to silicone polymer ligands for binding to quantum dots. The silicone polymer ligands contain a multiplicity of amine, carboxy, and / or phosphine binding groups suitable for attachment to quantum dots. The present invention also describes a process for the preparation of quantum dot binding ligands.

The invention discloses a method for adjusting the molecular weight of a polymer. The method is characterized in that a polymer contacts with a catalyst as a substrate under olefin metathesis reaction conditions, the polymer contains a carbon-carbon double bond, and the catalyst is a compound with the structure represented by formula I. The method can effectively adjust the molecular weight of existing polymers. Additionally, the method has the advantages of simplicity, easy implementation and mild reaction conditions.

The invention provides a diphenylmethyl-containing asymmetric diimine pyridine complex with nitro-enhanced thermal stability and catalytic activity, and a preparation method and application thereof. The complex has a single catalytic activity center, the molecular weight of a polymer can be regulated and controlled by changing a ligand structure and polymerization conditions, and the complex has the advantages of high catalytic activity, low cost, stable performance and the like. The complex and intermediates thereof have the advantages of mild preparation conditions, short period, simple operation conditions and the like. The asymmetric complex can be applied to a catalyst for ethylene polymerization and has high catalytic activity, and high molecular weight (up to 599.5 kg / mol) linear polyethylene is obtained; especially, the provided iron complex is high in thermal stability, and even at a high temperature of 100 DEG C, the catalytic activity can still be kept at 3.86* 10<6> g*mol<-1>(Fe)*h<-1>. Compared with reported non-nitro substituents (CH3, Cl), the complex has the highest activity and molecular weight. Therefore, the complex can be used at a high environmental temperatureas engineering plastic, and has great industrial application potential.

The invention discloses an expandable copolymer resin for manufacturing a lost foam casting model and a preparation method thereof and belongs to the field of lost foam casting materials. The expandable copolymer resin has the molecular weight of 150,000-300,000 and is prepared from a mixed monomer, deionized water, a cellulose ether dispersant, a sodium salt, an initiator, a foaming agent and a molecular weight regulator; the mixed monomer is prepared from MMA and ST, the MMA accounts for 70-95% of the weight of the mixed monomer, and the ST accounts for 5-30% of the weight of the mixed monomer; the sodium salt comprises at least one of sodium sulfate, sodium pyrophosphate and sodium dichromate; the foaming agent is prepared from n-pentane, isopentane and petroleum ether; the molecular weight regulator is prepared from at least one of divinylbenzene, ethylene glycol dimethacrylate, C8-C12 alkyl mercaptans, carbon tetrabromide and methyl styrene dimer. The model formed by the expandable copolymer resin has the advantage of reducing or eliminating carbon defects of castings during casting of cast iron and cast steel.

The invention discloses a class of fluorine-containing alpha-diimine nickel coordination compounds for preparing a polyolefin elastomer, and an intermediate thereof, wherein the coordination compoundhas a single catalytic activity center, the molecular weight of a polymer can be regulated and controlled by changing a ligand structure and polymerization conditions, and the coordination compound has the advantages of high catalytic activity, low cost, stable performance and the like. The invention further provides preparation methods of an asymmetric alpha-diimine nickel coordination compound containing a difluoro group, and an intermediate thereof, wherein the two preparation methods have the advantages of mild reaction conditions, short period, simple operation conditions and the like. The invention also provides uses of a metal nickel coordination compound and a catalyst system thereof, wherein the metal nickel coordination compound is used for catalyzing ethylene polymerization, shows good catalytic activity and obtains a polyethylene elastomer material with narrow molecular weight distribution. The obtained polyethylene elastomer material is high in branching degree, has good tensile strength, elongation at break and elastic resilience, is a thermoplastic elastomer material and has great industrial application potential.

The invention provides mechanochromic high-toughness nylon 6 and a preparation method thereof. The preparation method comprises the following steps: firstly, preparing an isocyanate-terminated polyurethane prepolymer; then, enabling excessive terminal isocyanate groups to react with hydroxyl groups of spiropyrane chromophore; adding an isocyanate-terminated spiropyrane derivative into caprolactammelt, carrying out an addition reaction on isocyanate and caprolactam, and finally injecting the mixture into a mold to carry out an anionic polymerization reaction to obtain the mechanochromic high-toughness nylon 6. According to the invention, the raw material ratio and reaction conditions are reasonably controlled, polyurethane chain segments and spiropyrane chromophore are introduced into a polyamide molecular chain, the position relation and molecular weight between the chain segments are reasonably regulated and controlled, the effectiveness of external force transmission of the preparedmechanochromic high-toughness nylon 6 is remarkably improved, and then the sensitivity of mechanochromic response of the spiropyrane chromophore is remarkably improved.

The invention discloses a preparation method for dextranase and application of the dextranase in preparation of low molecular dextran. The invention is characterized in that a producing bacterial strain for the dextranase is Penicillium aculeatum F1008 separated from soil and the bacterial strain is preserved in China General Microbiological Culture Collection Center with an accession number of CGMCC No. 8135. According to the invention, the dextranase with high enzyme activity is successfully prepared through fermentation culture of Penicillium aculeatum F1008; the dextranase has catalysis temperature of 25 to 35 DEG C, a catalysis pH value of 5.0 to 6.0 and average enzyme activity of higher than 600 U / mL, gives preference to reaction with a high-molecular-weight substrate in a multi-substrate solution and is especially applicable to preparation of low-molecular-weight dextran; low molecular dextran varieties prepared through catalysis of the Penicillium aculeatum F1008 dextranase comprise micromolecular dextran with weight average molecular weight of 10000 Da, 6000 to 8000 Da and 3000 to 5000 Da. The dextranase has the advantages of mild catalytic reaction condition, good substrate specificity, low energy consumption and capacity of achieving the objects consisting of yield increase, low carbon and low cost in production of micromolecular dextran.

The invention provides a pyridylimine group complex containing asymmetric fused rings and a preparation method and application of an intermediate of the pyridylimine group complex. The complex has high catalytic activity, can realize the regulation of the molecular weight of a polymer by changing a ligand structure and polymerization conditions, and has the advantages such as low cost and stable performance. The preparation method of the intermediate 2,3,7,8,9,10 hexahydro-1H-cycloheptaquinoline-4,6-dione compound and the complex has the advantages such as mild conditions, short cycle and simple operating conditions. The complex can be applied to a catalyst for ethylene polymerization, especially when an iron complex provided has high thermal stability, the catalytic activity can be as high as 15.86x10<6> g.mol<-1>(Fe)h<-1> under the action of a catalyst promoter MMAO, highly linear polyethylene is obtained, the catalytic activity can still be maintained at 5.44x10<6> g.mol<-1>(Fe)h<-1> even at a high temperature of 90 DEG C, the temperature is in line with the operating temperature of industrial production, and the pyridylimine group complex has good industrial application prospects.

A synthetic method of a styrene / maleic anhydride alternating copolymer with low molecular weight belongs to the field of macromolecular precipitation polymerization. Media and chain transfer agents used in the existing methods for preparing styrene / maleic anhydride copolymers by precipitation polymerization have disadvantages. In the synthetic method, the styrene / maleic anhydride alternating copolymer is prepared by taking a mixed solvent of organic acid alkyl ester and alkane as a reaction medium for the precipitation polymerization, alpha-methylstyrene or vinyl acetate as a molecular weightregulator and organic peroxide or an azo compound as an initiator for initiating a copolymerization reaction between styrene monomers and styrene. The synthetic method has simple process, the synthesized copolymer has good properties, and the method has the advantages of being economical, environment-friendly and the like.

The invention discloses a modifying method for activated carbon. The modifying method comprises the following steps of: firstly, carrying out oxidation pretreatment on the activated carbon to obtain activated carbon containing an oxygen functional group on the surface; secondly, reacting the activated carbon containing an oxygen functional group on the surface with a compound A to obtain initiator-modified activated carbon; thirdly, configuring a polymer system and carrying out an ATRP (Atom Transfer Radical Polymerization) reaction at 50-90DEG C; and fourthly, separating and purifying to obtain the surface polymer-modified activated carbon. The invention discloses a novel modifying method. According to the novel modifying method, by introducing a polymer chain segment to the surface of the activated carbon in a covalent bond manner, using the performances of the polymer chain segment and combining the characteristics of great surface area, porous structure and the like of the activated carbon, the regulation and control for physical and chemical properties are realized and thereby the dispersibility of the activated carbon in an organic solvent or water is improved.

The invention relates to a low-molecular-weight polymer with functionally modified ends and a preparation method thereof. The preparation method comprises a step of subjecting a low-molecular-weight polymerization monomer and a RAFT chain transferring agent to a copolymerization reaction in the presence of an initiator through radical polymerization so as to obtain the low-molecular-weight polymerwith functionally modified ends, wherein the low-molecular-weight polymerization monomer is one or more selected from the group consisting of a betaine type amphiphilic polymer monomer, an acrylamidemonomer, a quaternary ammonium salt type long-carbon-chain association monomer and 2-acrylamide-2-methylpropanesulfonic acid; and two ends of the formed polymer are function groups as described in the specification, and in the function groups, m is in a range of 1-3 and n is in a range of 2-4, so the ends of the polymerization monomers can be connected with each other through the non-covalent interaction, i.e., host-guest clathration. The molecular weight of the polymer is controlled below 1 million Da, and the underground rapid recovery and thickening of a solution after shearing are realized.

The invention discloses a C5 petroleum resin product and a preparation method thereof with controllable molecular weight, and belongs to the technical field of petroleum resin preparation. According to the preparation method of the C5 petroleum resin with controllable molecular weight, a C5 fraction obtained from ethylene cracking is used as a main raw material, the content of active monoolefin components in the C5 fraction is adjusted to be in a range of 10%-90%, the content of active diolefin components is adjusted to be in a range of 2-70%, and then the C5 petroleum resin is prepared through a cationic catalytic polymerization reaction, wherein the catalytic polymerization temperature is 30-80 DEG C, the polymerization reaction residence time is 50-300 minutes, the stirring speed of thereaction polymerization is controlled to be in a range of 50-350 rpm, and the addition amount of a catalyst is 0.25-0.85%. Through the adoption of the technical scheme provided by the invention, themolecular weight of the C5 petroleum resin product can be effectively regulated and controlled, the regulating and controlling range is large, and therefore application requirements of different fields and customers can be met.

The invention provides a preparation method and application of a diaryliminopyridyl complex containing flexible eight-membered ring and an intermediate thereof. The complex has multiple catalytic active centers, can achieve regulation of the polymer molecular weight by changing the ligand structure and polymerization conditions, and has the advantages of high catalytic activity, low cost, stable performance and the like. The preparation method of the intermediate alpha, alpha'-dioxo-2, 3:5, 6-bis(hexamethylene)pyridine compound and the complex has the advantages of mild conditions, short cycle, simple operation conditions, etc. The complex can be applied in catalysts for ethylene polymerization, especially the provided iron complex has high thermal stability, and under the action of a cocatalyst, the catalytic activity can reach 12.23*10<6>g.mol<-1>(Fe)h<-1>, and highly linear polyethylene with high molecular weight (188kg.mol<-1>) can be obtained, even at a high temperature of 90DEG C, the catalytic activity can still be maintained at 6.75*10<6>g.mol<-1>(Fe)h<-1>, meeting the operating temperature of industrial production, the complex has very good industrial application prospects.

The invention provides a class of asymmetric pyridineimine transition metal coordination compounds containing a large steric hindrance substituent, a preparation method and application thereof. According to the invention, the preparation method of the coordination compound is mild in condition, short in period and simple to operate; the coordination compound can be applied to a catalyst for ethylene polymerization, has a single catalytic active center, can regulate and control the molecular weight of a polymer by changing a ligand structure and polymerization conditions, and has the advantagesof low cost, high catalytic activity, good thermal stability and the like; And especially, compared with reported diphenylmethyl, the iron coordination compound provided by the invention has the advantages that the molecular weight of highly linear polyethylene obtained by catalyzing ethylene polymerization is high while high catalytic reaction activity and high thermal stability are maintained,wherein the molecular weight can reach 913.36 kg / mol, so that the coordination compound can be used as engineering plastic at a high environment temperature, is used for synthesizing high-molecular-weight linear polyethylene, and has great industrial application potential.

The invention provides a soluble linear conductive polymer and a preparation method thereof. The preparation method comprises the following steps: S1, taking S-dodecyl-S'-(R, R'-dimethyl-R''-(2-thienyl) ethyl acetate) trithiocarbonate as a chain transfer agent; carrying out a reversible addition-fragmentation chain transfer polymerization reaction on methyl acrylate, 2-(Dimethylamino)ethyl methacrylate and 1, 4-dioxane under the initiation of azodiisobutyronitrile to obtain polymethylacrylic acid N, N-dimethylaminoethyl ester-b-polymethyl acrylate; and S2, adding a 3, 4-ethylenedioxythiophenen-butyl alcohol solution into the polymethylacrylic acid N, N-dimethylaminoethyl ester-b-polymethyl acrylate hydrochloric acid solution, and carrying out interfacial polymerization reaction under theaction of a catalyst to obtain the soluble linear conductive polymer. The soluble linear conductive polymer is synthesized by adopting reversible addition-fragmentation chain transfer polymerization and interfacial polymerization methods, so that the length of a flexible chain segment of the soluble linear conductive polymer is controllable.

The invention provides a method for producing polymalic acid of different molecular weights. The method comprises the following steps: inoculating an aureobasidium pullulans seed solution to a fermentation medium, and fermenting to produce polymalic acid; controlling a content of asparaginic acid in the fermentation medium to be 0.25-0.45g / L; regulating the pH value of the fermentation liquor to 6.0-7.0 in the fermentation process; and producing the polymalic acid of different molecular weights. The fermentation process is regulated, and the polymalic acid of different molecular weights is obtained, so that the polymalic acid is widely and reasonably applied to the fields of foods, medicines, chemical industry and petroleum according to different polymerization degrees of the polymalic acid. Moreover, according to a synergistic effect between the asparaginic acid and the pH value, the fermentation medium is further optimized, and the molecular weight of the produced polymalic acid can be accurately oriented in a narrow range, so that the requirements of people for the polymalic acid with different polymerization degrees are met.

The invention provides a novel symmetrical seven-membered cyclopyridylimine metal complex containing a cycloalkane large-steric-hindrance substituent, a preparation method of the novel symmetrical seven-membered cyclopyridylimine metal complex and application to ethylene polymerization. A novel cycloalkane large-steric-hindrance structure enables the catalytic activity of the alpha,alpha'-dioxo-2,3:5,6-bis(pentamethylene)pyridine metal complex to be up to 10<7> g.mol<-1>.h<-1>, and the properties, especially thermal stability, are better. The catalytic active site of the complex provided is not limited to a single center, but the molecular weight of a polymer can still be regulated by changing the ligand structure and polymerization conditions. The complex provided can be used for catalyzing the ethylene polymerization together with a cocatalyst methylaluminoxane and modified methylaluminoxane to obtain highly linear polyethylene with high molecular weight (M<w> up to 272.0 kg.mol<-1>), and the shortcoming of low-molecular-weight polyethylene obtained by a previous catalyst is greatly overcome; and meanwhile, the linear polyethylene of different fine structures can be realized by regulating the temperature, and therefore, great industrial application value is achieved.

The invention discloses a polybutylene thermoplastic elastomer and a preparation method thereof. The polybutylene thermoplastic elastomer comprises: 10%-50% by mass of isotactic polybutylene, 45%-89.9% by mass of a block copolymerized elastomer, and 0.1%-5% by mass of atactic polybutene. The block copolymerized elastomer is a copolymer of butene and high-grade aliphatic alpha-olefin of 5-10 carbon atoms or aromatic olefin of 8-12 carbon atoms, and is a high isotactic polybutylene long block composed copolymer. According to the preparation method of the polybutylene thermoplastic elastomer, first a two-stage polymerization method is employed, butene firstly undergoes homopolymerization under the action of a loaded titanium catalyst, then butene and a comonomer copolymerize so as to obtain the polybutylene thermoplastic elastomer; and second, a multi-stage sequential polymerization method is employed, butene firstly undergoes homopolymerization under the action of the loaded titanium catalyst, then butene and the comonomer copolymerize, and homopolymerization and copolymerization are carried out in multiple cycles so as to obtain the polybutylene thermoplastic elastomer finally.