Mechanism of the Water-lsocyanate Reaction

Shkapenko, G.; Gmitter, G. T.; Gruber, E.

doi:10.1021/ie50607a031

Cited by 52 publications

(22 citation statements)

References 4 publications

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“…IPDI conversion to polymer is accomplished through several step: isocyanate groups in IPDI react first with water, leading to amine groups (NH 2 ), which in turn further react with isocyanate groups, leading to polyurea groups (RNHCONHR) in the polymer chains, or biuret units (CN(CONH) 2 ) when the hydrogen of urea unit in the newly formed polyurea further reacts with isocyanate groups as illustrated in Scheme . It is known that reaction of water with IPDI is a slow reaction, the subsequent reactions of isocyanate groups with the newly formed amine are faster than the amine‐yielding one,22 and therefore leading to highly crosslinked polyurea microspheres. It is easy to conceive that polyurea would not be formed if the reaction of IPDI with water was instantaneously accomplished; because isocyanate groups, which further react with the amine groups, were no more available in this case shortly after the start of polymerization, therefore, leaving amine‐terminated IPDI monomer or oligomers in the system.…”

Section: Resultsmentioning

confidence: 99%

A novel protocol for the preparation of uniform polymer microspheres with high yields through step polymerization of isophorone diisocyanate

Jiang

Kong

Zhu

2011

J. Polym. Sci. A Polym. Chem.

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Uniform polymer microspheres with neat surface are of high interests. Precipitation polymerization of vinylic monomers remains a very limited process owing to very low monomer concentration allowed. Here, a fully novel protocol for the production of uniform polymeric microspheres is presented. Using one single monomer, isophorone diisocyanate, highly monodisperse polyurea microspheres were achieved with very high yield in a very short time period via precipitation polymerization in water-acetone mixed solvent. Results demonstrated that the ratio of water-acetone and polymerization temperature played important roles in the process. The size of the microspheres was readily adjustable by varying monomer concentration, water/acetone ratio or polymerization temperature. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: [4492][4493][4494][4495][4496][4497] 2011

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Section: Resultsmentioning

confidence: 99%

A novel protocol for the preparation of uniform polymer microspheres with high yields through step polymerization of isophorone diisocyanate

Jiang

Kong

Zhu

2011

J. Polym. Sci. A Polym. Chem.

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“…Isocyanate‐group‐containing polymers are useful because various functional groups can be easily introduced to the polymers. However, the isocyanate group is highly labile to water, which makes them difficult to handle without a glove box or a dry clean room …”

Section: Introductionmentioning

confidence: 99%

“…However, the isocyanate group is highly labile to water, which makes them difficult to handle without a glove box or a dry clean room. 7 Chemical protection is usually needed when handling isocyanates in air atmosphere or in a nucleophilic solvent like water. 4 However, this can involve multiple reaction steps, which give some byproducts such as eliminated protecting groups.…”

Section: Introductionmentioning

confidence: 99%

Water‐stable copolymers containing isocyanate moiety protected by hydrophobic styrene segment and their reaction with amines

Seto

Matsumoto

Endō

2015

J. Polym. Sci., Part A: Polym. Chem.

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Reactive isocyanate groups were protected and stabilized by the hydrophobic styrene segment and acquired high tolerance toward water. Copolymers containing isocyanate groups were synthesized by a radical copolymerization of 2‐propenyl isocyanate (2PI) and styrene (St). The stability of the obtained copolymers on water was examined to find that isocyanate groups were protected by the hydrophobic polystyrene segment and were stable on water and these isocyanates reacted with primary amines including amino acids to form urea selectively on water. Primary amines with a higher octanol‐water partition coefficient or smaller steric hindrance were more reactive to the isocyanate groups in the side chain of the copolymer. The protection of reactive isocyanate groups using the hydrophobic styrene segment did not give side products which are produced in the usual chemical protection/deprotection process. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1934–1940

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“…According to the isocyanate reactivity, a reaction with water molecules is expected. 15,19 While solvent-borne PU polymers can be easily dissolved and analyzed with advanced methods (e.g., nuclear magnetic resonance), 9,26 a PUD analysis is limited due to a poor solubility of cross-linked and branched polymer chains. Colloidal physical parameters (e.g., particle size, particle size distribution, pH, conductivity) become of a greater importance in a PUD characterization.…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, some biuret formation is expected. 19 The reaction with carboxylic groups is retarded due to a steric hindrance and a dissociation. 5 The widely used dibutylamine back-titration method 7 was found inappropriate for the measurements of the residual NCO groups since high amounts of amine and water are involved.…”

Section: 2mentioning

confidence: 99%

Monitoring of polyurethane dispersions after the synthesis

Ocepek¹,

Zabret²,

Kecelj³

2015

Mater. Tehnol.

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Chemical and physical parameters of the aqueous polyurethane dispersion (PUD) were studied after the synthesis. A prepolymer mixing process with a limited-chain extension step was used in order to examine the polymer and dispersion behavior with respect to the ageing time. Measurements of free isocyanate groups were performed with the aid of Fourier transform infrared spectroscopy (FT-IR). The pseudo-first-order kinetics of NCO disappearance was proposed and the value of the corresponding constant was determined. Additionally, particle size, particle size distribution, pH, conductivity and molecular mass were monitored and compared. Keywords: polyurethane dispersion, colloid, FT-IR V raziskavi smo preu~evali spreminjanje kemijskih in fizikalnih parametrov vodne poliuretanske disperzije (PUD) po sintezi. Disperzijo smo sintetizirali po postopku vme{avanja prepolimera z omejenim podalj{evanjem verig za preu~evanje polimerne disperzije z ozirom na~as po sintezi. Merjenje prostih izocianatnih skupin smo izvedli z metodo Fourierjeve transformacijske infrarde~e spektroskopije (FT-IR). Predpostavili smo kineti~ni model psevdoprvega reda z ozirom na reakcije izocianatnih skupin ter dolo~ili vrednost kineti~ne konstante. Dodatno smo spremljali in primerjali povpre~ne velikosti delcev, porazdelitev velikosti delcev, pH, prevodnost in molekulsko maso.

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Mechanism of the Water-lsocyanate Reaction

Cited by 52 publications

References 4 publications

A novel protocol for the preparation of uniform polymer microspheres with high yields through step polymerization of isophorone diisocyanate

A novel protocol for the preparation of uniform polymer microspheres with high yields through step polymerization of isophorone diisocyanate

Water‐stable copolymers containing isocyanate moiety protected by hydrophobic styrene segment and their reaction with amines

Monitoring of polyurethane dispersions after the synthesis

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