189 results about "Temperature sensitive polymer" patented technology

The present invention relates to novel polymeric compositions that exhibit Reverse Thermal Gelation (RTG) properties for use as Support Materials (SM) in the manufacture of three-dimensional objects. These polymers are Temperature Sensitive Polymers that respond with a significant change of properties to a small change in temperature. Temperature Sensitive Polymers exhibit cloud point (CP) or lower critical solution temperature (LCST) in aqueous solutions. Water-soluble Temperature Sensitive Polymers are chosen to give low viscosity liquid at low temperature when dissolved in water and by that to permit easy dispensing at low temperature. Raising the temperature above their gelation temperature (Tgel) will result in solidification of the composition. At its gel position the material has favorable characteristics as a support and building material. The gel layers have the appropriate toughness and dimensional stability to support the model layers during the building process. After the building process is completed the gel can be cooled down to a temperature below its Tgel so the gel can liquefy and be removed easily by rinsing with water.

Devices and processes (e.g., improved Plasticized Melt Flow processes (PMF) or improved Phase Separation Polymer Concentration (PSPC), etc.) used to make resorbable and non-resorbable structures for treating and / or healing of tissue defects are disclosed. Among the advantages of using these improved processes are the preservation of molecular weight and the broadening of the processing conditions for temperature sensitive polymers and therapies This reduction in processing temperature, pressure and time can help to preserve the molecular weight and / or integrity of the final product or any additive incorporated therein. The present invention relates to an improved porous implant wherein the pores of the implant present a second modeling material on their surfaces. This second material provides a textured or roughened face to the internal surfaces of pores. Additionally, this second material can be incorporated in sufficient quantity to, among other things, create a microporous network connecting interior closed cell pores with the exterior of the device.

The invention provides a temperature-sensitive modified silica nanosphere and a preparation method and application thereof. The preparation method comprises the steps of: adding an alkali liquor into a mixture of a precursor and a solvent for reacting to get a silica nanosphere suspension, adding a silane coupling agent to a silica nanosphere suspension for reacting to get a crosslinking agent-modified silica nanosphere suspension; adding a temperature-sensitive polymer monomer, a crosslinking agent and an initiator to the crosslinking agent-modified silica nanosphere suspension for a polymerization reaction to get a temperature-sensitive modified silica nanosphere crude product; and cooling, filtering, washing and drying the temperature-sensitive modified silica nanosphere crude product to obtain temperature-sensitive modified silica nanospheres. The method adopts an in-situ one-step method, so that the resulting temperature-sensitive modified silica nanospheres have special surface properties and rheological properties. The present invention also provides the temperature-sensitive modified silica nanospheres by the method and application thereof in enhancing oil recovery.

A battery charger protection circuit (10) interposable between a charger system or charger battery (22) and a lead acid or gel cell charging battery (26) to allow 1-to-1 charging thereof while protecting against short circuit and reverse current conditions. The circuit (10) broadly comprises a printed circuit board (12); a self-resettable fuse (14); a Schottky barrier diode 16; and connection wires (18). The self-resettable fuse (14) includes a temperature-sensitive polymer fuse material operable at a predetermined maximum current, defined by the polymer fuse material's composition, to increase in electrical resistance and thereby reduce current flow.

The invention discloses an interface-cross-linked temperature-sensitive polymer vesicle and a method for preparing the same. The interface-cross-linked temperature-sensitive polymer vesicle is formed by a block copolymer which at least comprises a hydrophilic block, a cross-lined interstrand block and a temperature sensitive block, wherein the hydrophilic block forms the membrane shell of the polymer vesicle, the temperature sensitive block forms the membrane nuclear of the polymer vesicle, and the cross-lined interstrand block forms the interface of the polymer vesicle to cross-link the interface of the polymer vesicle to stabilize the structure of the vesicle, and thus the interface-cross-linked temperature-sensitive polymer vesicle is formed; as the vesicle is formed in an aqueous solution system and the interface of vesicle is cross-linked, the small molecule drug, macromolecular drug and probe molecule entrapment efficiency of the polymer vesicle, the circulation stability in vivo blood and the efficiency of endocytosis by tumor cells are improved; and as a result, the bioavailability of drugs is improved and the polymer vesicle can be expelled out of the body conveniently.

The invention relates to a temperature sensitive polyvinylidene fluoride (PVDF) gel film and a preparation method thereof. The temperature sensitive PVDF gel film comprises the following components in percentage by weight: 0.5-2.5 percent of temperature sensitive high polymer gel and 97.5-99.5 percent of PVDF polymer. The preparation method comprises the steps of: a, preparing the temperature sensitive high polymer gel: dissolving a temperature sensitive polymer monomer and a crosslinking agent into absolute ethyl alcohol, carrying out radical polymerization under the protection of nitrogen to obtain the temperature sensitive high polymer gel; b, preparing a film casting solution, dispersing the temperature sensitive high polymer gel obtained from the step a in an organic solvent, gradually adding a certain quantity of PVDF powder, dissolving, degassing to obtain the film casting solution; and c, preparing the gel film: scraping the film casting solution obtained from the step b on a clean and flat glass plate to form a liquid film, curing in a curing bath to form the film. The PVDF gel film prepared by using the method has aperture size ranging from 100 to 300nm, the surface in ahole of the PVDF gel film consists of the temperature sensitive high polymer gel, the temperature sensitive high polymer gel can generate response according to the environment temperature change so as to cause that the film hole size is changed; and the invention can be used in intelligent selective separation of separated matters.

The invention provides a novel temperature-sensitive polymer and a method for preparing the novel temperature-sensitive polymer from L-lysine as a renewable resource, and belongs to the technical field of polymers. The novel temperature-sensitive polymer has a structure shown in the formula (VII). The novel temperature-sensitive polymer is prepared from a renewable resource L-lysine as an initial raw material. The novel temperature-sensitive polymer has an amide structure similar to the structure of poly(N-isopropylacrylamide). Through an ultraviolet spectrophotometer, polymer aqueous solution light transmittance variation with a temperature is determined so that it is showed that the polymer has good temperature sensibility. The invention also provides the method for preparing the novel temperature-sensitive polymer from L-lysine as a renewable resource. The method has simple processes and utilizes the cheap raw materials.

The invention relates to temperature-sensitive polymer / gold nanoparticle hybrid microspheres and a preparation method thereof. The temperature-sensitive polymer / gold nanoparticle hybrid microspheres consist of more than 99.9 weight percent of polymer and less than 0.1 weight percent of gold nanoparticles. The preparation method comprises the following steps of: a) preparing a 2-(methoxycarbonyl)-ethyldithiophenyl ester chain transfer agent; b) synthesizing an N-isopropylacrylamide macromolecular chain transfer agent by using 2-(methoxycarbonyl)-ethyldithiophenyl ester obtained in step a) and azodiisobutyronitrile; c) further polymerizing 4-vinylpyridine by using the macromolecular chain transfer agent obtained in step b) and the azodiisobutyronitrile to obtain a block copolymer; d) preparing polymer microsphere suspension by using the block copolymer obtained in step (c); and e) adding chloroauric acid into the microsphere suspension, and reducing by using excessive sodium borohydride to obtain the temperature-sensitive hybrid polymer microspheres. The temperature-sensitive polymer / gold nanoparticle hybrid microspheres overcome the disadvantages that the gold nanoparticles are not firmly combined and are easy to fall off and the catalytic activity is not adjustable, and can be used for the fields of controllable catalysis and the like.

The invention relates to a preparation method of a base pair-containing multiple responsive polymer. According to the preparation method, a two-block polymer is prepared from polycaprolactone and a temperature sensitive responsive polymer by an active polymerization method, a basic group is connected to one end of the two-block polymer, another basic group is connected to one end of polyethylene glycol, the two basic groups form a complementary base pair, a hydrogen bond of the complementary base pair has salt and pH response functions, and the two-block polymer contains a disulfide bond and the temperature sensitive polymer and thus the base pair-containing multiple responsive polymer has multiple responsiveness to salts, a pH, a temperature and redox. Polycaprolactone and polyethylene glycol used by the preparation method have good biocompatibility, the polymer formed by base complementary can form micelle in an aqueous solution by self-assembling, and through a change of the environment, micelle morphology is changed. Through the base pair-containing multiple responsive polymer, use of a drug release method can be realized. The preparation method has simple processes and can be controlled easily.

The invention provides a temperature-sensitive core-shell vesicle controlled-release drug carrier which consists of liposome at the inner core and temperature-sensitive polymer composite gel at the outer layer. The stability of vesicle can be improved by core-shell configuration, and both the liposome at the inner core and the temperature-sensitive biological polymer composite gel at the outer layer can be used as drug carriers for carrying drugs. As the temperature raises, the gel at the outer layer varies so as to shrink, the drugs covered by the gel at the outer layer can be quickly released by means of temperature control, and the content of the liposome at the inner core can be slowly released owing to the presence of the gel at the outer layer, therefore, the effect of multidimensional release is achieved. The drug release carrier provided by the invention has outstanding biocompatibility and quick temperature response, can be used not only in the field of cosmetics, but also asthe carrier for an embedded drug, and is applied to implantation in open operation, injection in minimally invasive surgery and implantation by means of an endoscope.

The invention discloses a multifunctional temperature-sensitive gel composite dressing for wound healing and preparation and usage thereof. The dressing comprises a quaternized chitosan derivative and an aldehyde-terminated temperature-sensitive polymer, a mass ratio of the two components is 1:15-1:25, wherein a molecular weight of chitosan for preparing quaternized chitosan is between 100 thousands and 1000 thousands, the degree of deacetylation is above 90%, and the degree of quaternized substitution is 10%-45%. The dressing is a thick liquid easy to apply to a wound at room temperature, and after it is applied to the wound, a gel film coating may form within 1 min. The temperature-sensitive gel composite dressing prepared based on the invention has autonomous antibacterial and anti-inflammatory effects and good film-forming stability, may also provide a wet environment and a sustained drug release function and is useful for treating and healing wounds such as diabetic foot ulcers.

The invention relates to a method for forming a metalized pattern using jet printing and a molded interconnected assembly thereof. The method for forming a metalized pattern using jet printing comprises: modifying the surface of a nonmetallic base material by using a mechanical method or chemical method; coating the surface of the improved base material with the metalized pattern in a jet printing manner by using precious metal accelerant ink of temperature-sensitive polymer with catalyst metallic particles; forming the metalized pattern on a part where the precious metal accelerant ink is jet printed by using an electroless electroplating method, wherein the viscosity and the surface tension of the precious metal accelerant ink are adjusted by a viscosity modifier; and improving the adhesion of the metalized pattern and the base material by using the temperature-sensitive polymer. The invention further discloses a 2D or 3D molded interconnected assembly by forming a metalized pattern on a molded assembly by using the method for forming a metalized pattern using jet printing, wherein the molded interconnected assembly is applied to RFID, mobile communication device housing, automobile electronic assemblies, and 3D LED assemblies.

A nucleic acid amplification disk apparatus using a temperature sensitive polymer synthesis and the analysis method using the same, and more specifically, and the nucleic acid amplification device, and the analysis method using the nucleic acid amplification disk unit and the nucleic acid amplification disk for amplifying the Bacterial DNA or RNA, and the driving control section for controlling the nucleic acid amplification disk.

The invention belongs to the fields of high polymer chemistry and biomedical engineering, and particularly discloses a pH and temperature sensitive polymer. The polymer is composed of a hydrophilic polyethylene glycol segment, and a lyophobic poly-(aspartic acid-diethyl-ethylenediamine-co-histamine-co-diisopropyl ethylenediamine) segment, and the ratio of the hydrophilic segment to the lyophobic segment is (1:10)-(1:12). The pH and temperature sensitive polymer can be used for preparing nano-vesicles loaded with hydrophilic anti-tumor drugs or / and ultrasonic contrast agents, and the nano-vesicles can be used for preparing tumor diagnosis drugs or tumor treatment drugs.

The invention discloses a hydrophobic monomer for synthesizing a temperature sensitive polymer oil-displacing agent and a preparation method thereof, which belong to the technical field of the design of oilfield chemical agents. In order to solve the problems of bad temperature resistance, salt resistance and anti-shear ability of a part of hydrolyzed polyacrylamide serving as an oil-displacing agent and solve the problems of complex synthesis method, dissolution difficulty and high cost of modified temperature-resistant and salt-resistant polymer oil-displacing agents, the invention provides a method for synthesizing a temperature sensitive polymer oil-displacing agent with a thermo-thickening function by copolymerizing poly N-alkyl acrylamide, acrylamide and a temperature-resistant, salt-resistant and hydrophobic monomer. According to the design, n-butylbenzene is used as a raw material, and the hydrophobic monomer p-n-butylbenzene ethylene is synthesized through three chemical reactions of Friedel-Crafts acylation, negative hydrogen transfer reduction and dehydration of alcohol to alkene. The reaction conditions are mild, the purification method is simple, the product is pure, and the requirements of temperature resistance and salt resistance of the hydrophobic monomer for forming the temperature sensitive polymer oil-displacing agent can be met.

The invention discloses a preparation method of a photo-thermal and chemotherapeutic precise synergic antitumor temperature-sensitive gold nanocage hydrogel drug carrying system. The preparation method comprises the following steps of: 1) mixing a gold nanocage with a high-temperature ligand, stirring and incubating the mixture and performing centrifugation to obtain a high-temperature ligand-modified gold nanocage, wherein the high-temperature ligand is a chain-like temperature-sensitive polymer containing a disulfide bond, and the phase change temperature of the high-temperature ligand is 39-50 DEG C; 2) dispersing the high-temperature ligand-modified gold nanocage obtained in the step 1) in an ammonium sulfate solution, stirring and centrifugalizing the mixture, dispersing a solid with an aqueous solution of adriamycin, and leaving the mixture to stand in a dark place to obtain a drug-carrying gold nanocage; and 3) mixing the drug-carrying gold nanocage obtained on the step 2) with a low-temperature ligand, and stirring and incubating the mixture and performing centrifugation to obtain the photo-thermal and chemotherapeutic precise synergic antitumor temperature-sensitive gold nanocage hydrogel drug carrying system, wherein the low-temperature ligand is a chain-like temperature-sensitive polymer containing a disulfide bond, and the phase change temperature of the low-temperature ligand is 26-35 DEG C.

A temperature-sensitive filtering membrane with small pore size distribution is designed and prepared based on the thought of bionics by taking a metal chloride saline solution as a solvent in order to solve the problems that a large number of organic solvents hard to recycle are used in the traditional film preparation process, consequently, environmental pollution is caused, a polymeric membrane material is wide in membrane pore size distribution, and the membrane is in lack of responsiveness and is likely to be contaminated. Firstly, a temperature-sensitive polymer N-isopropylacrylamide is prepared in the metal chloride saline solution in a polymerization mode, and then N-isopropylacrylamide is homogeneously grafted with polyacrylonitrile to obtain a membrane casting solution; then the membrane casting solution is placed in a coagulating bath of water, metal ions and chloridions are gradually dispersed into the water, and a N-isopropylacrylamide grafted polyacrylonitrile polymer is subjected to phase transformation to form the membrane. The metal ions and the chloridions achieve a hole forming function, N-isopropylacrylamide and polyacrylonitrile are subjected to microphase separation, and a hydrophili channel subjected to ion hole forming is formed in the interface of N-isopropylacrylamide and polyacrylonitrile. The filtering membrane is expected to be used for the fields of fine separation, temperature response membrane on-off and the like.

The invention discloses an improved direct writing forming method for preparing a three-dimensional structure. The method has the advantages that an aqueous solution, a temperature sensitive polymer or a temperature sensitive dispersant, a powder material and the like are subject to ball milling, so as to prepare temperature sensitive suspension liquid with good low-temperature fluidity and good high-temperature forming property; the temperature sensitive suspension liquid is subject to direct writing forming to prepare a blank, and the blank is further subject to heat treatment or debinding and sintering, so as to obtain the three-dimensional structure; the temperature change property of the temperature sensitive suspension liquid selected by the method is not related to the type of the powder material, various organic or inorganic materials can be selected to prepare the three-dimensional structure through the direct writing forming way, and the defect of easiness in blockage of a needle nozzle caused by the original suspension liquid in the direct writing forming process is overcome by the temperature change suspension liquid; meanwhile, the three-dimensional structure with accurate structure and large dimension can be prepared according to the design, and the decimeter-level, centimeter-level, millimeter-level, micrometer-level or nanometer-level three-dimensional structures can be prepared according to the selection of different powder materials or needle nozzles with different hole diameters.

The invention relates to an injectable medical slow release material which is mainly formed by the mixing of pulse type releasing microspheres carrying drugs and a temperature sensitive polymer solution. The preparation method mainly comprises the steps of preparing the pulse type releasing microspheres carrying drugs; preparing the temperature sensitive polymer solution; and mixing the pulse type releasing microspheres carrying drugs with the temperature sensitive polymer solution, and stirring the mixture to be uniform to form a mixed solution. According to the invention, carrying factors or microspheres of drugs are uniformly dispersed in the solution of the temperature sensitive injectable carrier, and after the solution is injected to a treatment position, the material is solidified quickly and then degrades slowly to release drugs or factors, so as to prolong the active time of the factors in the body, and improve the controllability on factor release speed and factor release cycle, thereby realizing the combination of release of same or different drugs in desired locations and different time slots alternatively and the manner of minimally invasive treatments.

The invention discloses double-magnetic-response temperature-sensitive microcapsules and a preparation method thereof. A temperature-sensitive polymer is coated on the surface of magnetic nanoparticles and filled into the wall material of the microcapsules; under the action of an alternating magnetic field, the magnetic particles generates heat due to a magnetic lag effect the temperature of the magnetic particles thus rises, and when the temperature T is higher than the lowest critical solution temperature (LCST), the wall material forms lots of pores due to the shrinkage of the temperature-sensitive nanoparticles, the diffusion resistance to the medicine molecules passing through the wall material of the microcapluses is small and the release speed is high; and when the temperature T reaches the LCST, the temperature-sensitive magnetic nanoparticles expand to fully fill the pores in the wall material of the microcapsules, the diffusion resistance to the medicine molecules passing through the wall material of the microcapsules is big, and the release speed is low. Therefore, by regulating the synergetic effect between the temperature-sensitive structure of the temperature-sensitive polymer on the surfaces of the magnetic nanoparticles and the magnetothermal effect of the alternating magnetic field, the controlled release of the embedded medicine is realized. The microcapsulesprepared by the invention have double magnetic response and a temperature-sensitive controlled-release property.

The invention provides a thick oil huff and puff deep channel blocking system and an injection method thereof. Solidification channel blocking agent composed of sodium and soil aqueous solution with the mass fraction of 4.0% to 6.0% and cement slurry with the mass fraction of 4.0% to 6.0% is adopted in a near wellbore zone, wherein the volume ratio of the two solutions is (0.8 to 1.2) : 1; temperature resistance supermolecule channel blocking agent composed of HPAM (polyacrylamide) aqueous solution with the mass fraction of 4.0% to 6.0% and phenolic resin aqueous solution with the mass fraction of 1.0% to 1.4% is adopted in a transition zone, wherein the volume ratio of the two solutions is (0.8 to 1.2) : 1; and temperature sensitive polymer aqueous solution with the mass fraction of 2.0%to 4.0% is taken as thermal thixotropic channel blocking agent in a far wellbore zone. According to the invention, steam channeling of large porous channels is blocked with the solidification channelblocking agent and the temperature resistance supermolecule channel blocking agent, and steam channeling generated by fine slits is blocked with the thermal thixotropic channel blocking agent, so that the purpose of deep channel blocking is achieved through combined blocking of the blocking agents.

The invention discloses a preparation method of an intelligent nano-foam oil-displacing agent. By grafting a temperature-sensitive polymer onto magnetic nano particle surfaces, compound nano particleswith the temperature-sensitive property and magnetic response are prepared, and the nano particles have the property of stabilizing foam. The oil-displacing agent has the characteristics that the hydrophilia and lipophilicity of the oil-displacing agent can be adjusted and controlled; when the formation temperature is high, the nano particles show the lipophilicity, and when the foam meets crudeoil, the foam bursts, which is beneficial to peeling the crude oil off a rock stratum surface and improving the recovery ratio; when the temperature is low, the nano particles show the hydrophilia, which is beneficial to separation of oil and water, and through an applied magnetic field, recovery of the nano particles can be fast achieved; moreover, the foam-displacing liquid can respond to the magnetic field, so that through the applied magnetic field, flow of the displacing liquid can be controlled.

The invention discloses a galactosyl-based temperature-sensitive polymer hydrogel and a preparation method thereof. The hydrogel is a Poly (NIPAAm-co-GAC) copolymerized hydrogel. The preparation method comprises three steps of: (1) synthesizing an intermediate L-NH2 with an aminogalactose group; (2) synthesizing an intermediate monomer GAC with galactosyl group and double bonds; and (3) preparing the Poly (NIPAAm-co-GAC) copolymerized hydrogel by using the NIPAAm (N-isopropylacrylamide) and the intermediate monomer GAC. The hydrogel has good temperature response and biocompatibility, and has good identification effect on hepatocytes; and can be used as a matrix material in tissue engineering for promoting cell adhension and growth in cell culture, and the cells can be automatically detached due to the temperature sensitivity of the hydrogel.

The invention discloses a temperature sensitive polymer material with biodegradability and biocompatibility. A preparation method of the material comprises the following steps of: firstly synthesizing monomers with specific structures by using the basic raw materials including lysine, tartaric acid, and malic acid, and carrying out polymerization reaction on the monomers with different ingredients to prepare the heterochain type polymer material. The polymer not only has good temperature sensitivity, but also has good biodegradability and biocompatibility. The preparation method disclosed by the invention is simple and easy to implement and has good industrial prospect.

The invention relates to a preparation method of thermo-magnetic dual responsive mesoporous silicon microspheres. The preparation method comprises the following steps: 1) synthesis of magnetic nanoparticles; 2) preparation of Fe3O4@SiO2 nanoparticles; 3) synthesis of magnetic responsive mesoporous silicon microspheres [M-MSN-CTAB (Magnetic-Mesoporous Silicon Nanoparticle-Cetyltrimethyl Ammonium Bromide)]; 4) modification of M-MSN-CATB; 5) preparation of the thermo-magnetic dual responsive mesoporous silicon microspheres [M-MSN-PNIPAAm (Poly N-Isopropyl Acryl Amide)]. The preparation method provided by the invention is reasonable in design method and simple and feasible in operation, and can be used for successfully preparing novel thermo-magnetic dual responsive M-MSN by taking superparamagnetic Fe3O4 nanoparticles as a core, mesoporous silicon as a middle interlayer and a temperature sensitive copolymer as a shell. The M-MSN-PNIPAAm has the characteristics of superparamagnetism, high specific surface area and high pore volume of mesoporous silicon and temperature response. The M-MSN-PNIPAAm can be used as a carrier of medicines to prevent medicines and active components from being damaged, and purpose of targeted delivery and controlled release is realized.

A functionalized temperature-sensitive polymer, a preparing method thereof and applications of the polymer is disclosed. The structure formula of the polymer is shown as a formula I. The preparing method includes subjecting a temperature-sensitive monomer and a functional monomer to free radical polymerization under the existence of an initiator to obtain a temperature-sensitive polymer; subjecting the temperature-sensitive polymer and hydrazine hydrate to an acylhydrazine conversion reaction to obtain a hydrazide-modified temperature-sensitive polymer; and reacting the hydrazide-modified temperature-sensitive polymer with 2-(diphenylphosphino) terephthalic acid 1-methyl 4-pentafluorophenyl diester. An azide-marked O-G1cNAc modified protein enriching mechanism of the functionalized temperature-sensitive polymer is based on a Staudinger ligation reaction between azide and triphenylphosphine, and the reaction is high in biological orthogonality, high in yield in an aqueous solution, specific and stable and does not need a catalyst, and therefore the reaction has good compatibility with subsequent mass spectrum identification. The method greatly increases the amino acid sequence coverage rate of low-abundance O-G1cNAc modified protein mass spectrum identification in a mixed sample.

The invention relates to the preparation and application method of a temperature sensitive micelle with magnetocaloric effect, belonging to the field of drug carrier in biological medicine, which adopts the technical proposal that: a quantity of temperature sensitive polymer is dissolved into an organic solvent; then the organic solvent together with drugs and Mn-Zn ferrite nanometer particles undergoes dialysis process in a great amount of deionized water to get a temperature sensitive micelle with magnetocaloric effect; and finally after certain biological treatment, the micelle is injected into human body; which is characterized in that an outside magnetic field locates the drug carrier near the tumor site; at the same time an alternating magnetic field raises the temperature of the micelle to reach the lowest critical temperature, so that the drug is released at the shrinking of the micelle. The method has an advantage that a new type of bio-control sustained release carrier is provided for the field of biological medicine.

The invention discloses a poly N-isopropyl acrylamide-sodium alginate double-layer coated temperature-sensitive slow-release nitrogen fertilizer. A method for preparing the poly N-isopropyl acrylamide-sodium alginate double-layer coated temperature-sensitive slow-release nitrogen fertilizer includes carrying out oxidation treatment on sodium alginate by the aid of sodium periodate to obtain oxidized sodium alginate; coating urea with the oxidized sodium alginate to obtain sodium alginate coated urea micro-spheres; synthesizing temperature-sensitive polymer poly N-isopropyl acrylamide microgel;carrying out fluidized bed spray granulation on the temperature-sensitive polymer poly N-isopropyl acrylamide microgel to obtain the poly N-isopropyl acrylamide-sodium alginate double-layer coated temperature-sensitive slow-release nitrogen fertilizer. The sodium periodate is used as an oxidizing agent. The oxidized sodium alginate is used as a base material. The temperature-sensitive polymer poly N-isopropyl acrylamide microgel is used as a temperature-sensitive envelope material. The poly N-isopropyl acrylamide-sodium alginate double-layer coated temperature-sensitive slow-release nitrogenfertilizer and the method have the advantages that temperature-sensitive polymers are led into the surfaces of the sodium alginate coated urea micro-spheres, accordingly, double-layer slow-release coating can be carried out on nitrogen fertilizers, effects of retaining the poly N-isopropyl acrylamide-sodium alginate double-layer coated temperature-sensitive slow-release nitrogen fertilizer can berealized, and loss and wastage of fertilizers can be reduced; aldehyde sodium alginate can be degraded without special conditions with specific enzymes and the like, and accordingly the problem of secondary pollution can be solved.