Synthesis of Stereocontrolled Polyurethanes with Defined Monomer Order by Step-economy Approach
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Polyurethanes are valuable materials in the industrial sector due to their broad scope of various applications. Traditional synthesis methods rely on step-growth polymerization, which inherently lacks precise molecular weight and structure control. Consequently, pursuing a synthetic strategy for stereocontrolled, sequence-defined polyurethanes represent a substantial challenge in soft material design. This study demonstrates an approach to synthesising discrete, stereo-regulated polyurethanes with defined monomer order by combining the one-pot synthesis method with iterative exponential growth. This work presents a methodology to fabricate non-biological polymers with structural precision characteristics for biomacromolecules. By varying the composition of different monomers and gradually increasing the chiral monomer content or altering its position within the polymer chain, we can influence the secondary structures of polyurethanes and, consequently, their properties and functions. Furthermore, we demonstrated the production of polymers with non-symmetrical sequences, showcasing the feasibility of tailoring polymer chains to specific requirements and preserving complete sequence control. This synthetic strategy paves the way for the facile fabrication of abiotic polymers that could emulate the characteristics of artificial proteins.Keywords:
Sequence (biology)
Step-growth polymerization
Limited monomer solubility imposes very intriguing features on poly(p-phenylenebenzobisoxazole) polymerization. Only one type of functional group is detected at oligomer chain ends, and a high-molecular-weight polymer is obtained even when an excess of the monomer with low solubility is used. These remarkable phenomena are interpreted as an unprecedented "spoon-feeding-of-monomer" mechanism. A novel apparatus for staged polymerization is described that was triggered by the uniqueness of the heterogeneous step-growth polymerization. Hyperbranched polyesters and a polyurethane/polyethylene blend, which represent two phases in the polymerization process, are also discussed.
Kinetic chain length
Chain-growth polymerization
Step-growth polymerization
Oligomer
Chain transfer
Bulk polymerization
Precipitation polymerization
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Abstract Polyurethane has attracted the great attention of scientists because of its lightweight, high toughness, good wear resistance and corrosion resistance. In the past, polyurethane was mainly used in low‐end products because of its single function. With the development of science and technology, ordinary polyurethane has been unable to meet the diverse needs of people. In recent years, scientists have developed a lot of functional polyurethane: self‐healing polyurethane, antifouling polyurethane, antibacterial polyurethane, shape memory polyurethane and electromagnetic shielding polyurethane. Polyurethane with a single function has been reported by many people, while polyurethane with multiple functions has been rarely reported. This review comprehensively reviews the structural design and applications of functional polyurethane. In addition, the advantages and disadvantages of chemical grafting functional polyurethane are introduced emphatically. Finally, challenges and future research directions of functional polyurethane are also discussed.
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The self-emulsified polyurethane microspheres were synthesized by combining prepolymerization,chain-extension,neutralization and emulsification methods in one step.The synthetic conditions of self-emulsified polyurethane microspheres were researched.The conditions include the kinds of diisocyanates,the feed ratios of isophorone diisocyanate(IPDI) and polypropylene glycol(PPG),emulsification time,reaction time,polymerization time and stirred velocity etc.And the conditions affected morphology of microsphere and emulsion stability.The degradable self-emulsified polyurethanes(SEPUL) were synthesized with IPDI,PPG and poly(lactic acid)(PLA).And the degradation property was researched in phosphate buffer solution(PBS).The structure and morphology of polyurethane microspheres were measured with infrared spectrum and scanning electron microscope.We found the best conditions to synthesize the stable,mean and globose selfemulsified polyurethane microsphere.
Isophorone diisocyanate
Polypropylene glycol
Glass microsphere
Step-growth polymerization
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Acenaphthylene
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The key research of anionic aqueous polyurethane,the factors to affect the performance of aqueous polyurethane and processing mechanism of waterborne polyurethane dispersion were discussed in this paper.The progress on its modifying of anonic aqueous polyurethane was summarized.Some suggestions of the progress of waterborne polyurethane for the future was put forward.
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Polyurethanes are versatile materials used widely in many applications. Annual production of polyurethanes is increasing day by day. The most important application of polyurethane covering its major market is polyurethane foam. Flexible and rigid foams are two major types of polyurethane foam used widely. Flexible and rigid foam samples were synthesized on lab scale by cup foaming. All samples were characterized by finding density of each sample. Cream, gel and rise time were also estimated for each sample. The chemical compositions of all polyurethane foam samples were characterized by FTIR analysis.
Characterization
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This paper evaluated the function and importance of aqueous polyurethane dispersions. The research development of aqueous polyurethane dispersions was reviewed, too. The methods for preparing aqueouos polyurethane dispersions were summarized. It was told that the main method was that in the systems of aqueous polyurethane dispersions both vinyl group and isocyanate group were used simultaneously to form interpenetrating polymer networks. Finally the application development trend of aqueous polyurethane dispersions was pointed out.
Isocyanate
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Abstract Water‐dispersible polyurethanes are a greener alternative to polyurethane solutions in organic solvents. Various polyurethane materials were prepared by a two‐step polymerization procedure of polypropylene glycol with M n of 2000, polyethylene glycol with M n of 1500, and diisocyanates with different chemical structures, aliphatic, cycloaliphatic and aromatic. It was investigated how the diisocyanate structure affected the molecular morphology, contact angle measurements, and physical characteristics of water‐dispersible polyurethanes. FTIR and NMR measurements showed a close relationship between the intermolecular connections and the hard segment structure, mainly of the diisocyanate used. Also, the polarized light method showed that the presence of the PEG in the hard domain improved aggregation through physical interactions due to its structural flexibility and mobility. These water‐dispersible polyurethanes can assure the use of these polyurethane materials in a broad range of applications with increased environmental protection.
Polypropylene glycol
Step-growth polymerization
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Research progress of application of polyurethane in functional polymers was reviewed in this paper.The study of biodegradable polyurethane,medical polyurethane,conductive polyurethane,antistatic polyurethane,antibacterial polyurethane and luminous polyurethane were introduced.The prospective development of these polyurethane is put forward.
Antistatic agent
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