Side Reactions in the Formation of Polyurethanes: Model Reactions Between Phenylisocyanate and 1-Butanol

Špírková, Miléna; Kubín, M.; Dušek, Karel

doi:10.1080/00222338708076935

Cited by 32 publications

(14 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results showed that DS NCO is always lower than DS TDI , which confirms that the o-NCO groups of TDI are not unreactive during CNC carbamation (Table 1) and can still react with neighboring hydroxyl groups or undergo some side reactions [30]. This may explain the inability of some reports to graft certain functional polymers on a CNC surface in amounts equivalent to the amount of TDI placed earlier on that surface as not all of those TDIs had free isocyanate groups [19].…”

Section: Quantification Of the Free Isocyanates Of Tdi-carbamated Cncmentioning

confidence: 54%

A Simple Method for the Quantification of Free Isocyanates on the Surface of Cellulose Nanocrystals upon Carbamation using Toluene Diisocyanate

Abushammala

2019

Surfaces

View full text Add to dashboard Cite

In many reports, cellulose and nanocellulose have been carbamated using 2,4-toluene diisocyanate (2,4-TDI) to allow the grafting of molecules or polymers onto their surfaces. Such a process usually involves the reaction of the more reactive isocyanate group of TDI (para-NCO) selectively with a hydroxyl group from the cellulose surface, followed by the reaction of the free isocyanate (ortho-NCO) with a desired molecule. After the first step, it is not possible, using elemental analysis, to determine the amount of ortho-NCO on the cellulosic surface, as an ideal para/ortho selectivity is difficult to obtain. This paper presents a simple method for the quantification of ortho-NCOs on the surface of cellulose nanocrystals upon TDI-based carbamation. It relies on the pH increase upon a complete hydrolysis of ortho-NCOs to amine groups using acidified dimethylsulfoxide. The method was found to be accurate and valid for a degree of substitution of up to 20%.

show abstract

Section: Quantification Of the Free Isocyanates Of Tdi-carbamated Cncmentioning

confidence: 54%

A Simple Method for the Quantification of Free Isocyanates on the Surface of Cellulose Nanocrystals upon Carbamation using Toluene Diisocyanate

Abushammala

2019

Surfaces

View full text Add to dashboard Cite

show abstract

“…Okuta [11] dissolved the formed polyurethane networks in dimethylsulfoxide, DMSO and dimethylacetamide, DMAc, by degrading the allophanate and biuret linkages with aliphatic primary amine followed by NMR analysis of the degradation products to yield quantitative information about crosslinks. Spirkova et al [12] and Schwetlick et al [3] used HPLC to identify the reaction products with model compounds, in the same way as Sebenik [13] with SEC and 13 C NMR.…”

Section: Introductionmentioning

confidence: 99%

“…According to Spirkova, no secondary reactions [12] can occur at room temperature without catalyst. At 50°C, in acetonitrile, Schwetlick [3] identified 3 different reaction conditions: at equimolar NCO/OH ratios, with or without catalysts like tin carboxylates and common tertiary amines, urethane is the main product when isocyanates react with alcohols, the kinetic rate constants are in the order k a >> k b ≈ k c (see Fig 1 for the reactions).…”

Section: Introductionmentioning

confidence: 99%

Reactivity of isocyanates with urethanes: Conditions for allophanate formation

Lapprand

Boisson

Delolme

et al. 2005

Polymer Degradation and Stability

124

View full text Add to dashboard Cite

The reactions between two polyisocyanates, 4,4'-methylenebis(phenyl isocyanate) (MDI) and trimer of isophorone diisocyanate (tIPDI) and a model aryl-alkyl diurethane were carried out at high temperature (≥ 170°C) and several NCO/urethane ratios. A combination of 1 H & 13 C NMR and MALDI-TOF spectroscopies was used and allows the identification of reaction products. When MDI or tIPDI is reacted with a diurethane at high temperature and after cooled, allophanates are formed but no isocyanurates. 13 C NMR was used to quantify the different reaction products obtained under different experimental conditions. Only a few allophanates (≤ 10%) are obtained after 1h of reaction.

show abstract

“…To minimize the reaction of diisocyanates with water which competes with the reaction of hydroxyl groups from diols and could cause a considerable decrease of PU molecular weight, a very dry acetone with water content lower than 0.0075 wt % was used. In addition, the organo‐tin catalyst (dibutyltin dilaurate) was used to accelerate the urethane‐forming reaction with aliphatic diisocyanates and suppress the side reactions with water even more . The main advantage of acetone is that a relatively low content of DMPA is necessary to produce stable dispersion .…”

Section: Methodsmentioning

confidence: 99%

Preparation and characterization of thermoplastic water‐borne polycarbonate‐based polyurethane dispersions and cast films

Serkis

Poręba

Hodan

et al. 2015

J of Applied Polymer Sci

View full text Add to dashboard Cite

Stable water-borne polyurethane dispersions (PUDs) were prepared from bifunctional aliphatic polycarbonate-based macrodiol, 2,2-bis(hydroxymethyl)propionic acid (DMPA), 1,6-diisocyanatohexane, 1,4-butanediol (BD), and triethylamine. Water-borne dispersion particles are thus solely formed from self-assembled linear PU chains. Both PUDs and PUD-based films were characterized with regards to the concentration of DMPA (ionic species content) and BD (hard-segment content). Average particle size of PUDs decreased and their long-term stability increased with increasing DMPA and decreasing BD concentration. Functional properties of cast films made from PUDs are substantially influenced by the character of the original colloidal particle dispersions. The swelling behavior of the films, their surface morphology, and mechanical properties are more influenced by DMPA than BD contents. At DMPA concentrations higher than 0.2 mmol g 21 of the solid mass of polyurethane, distinct self-organization of individual nanoparticles into fibril-like structures was detected by atomic force microscopy and scanning electron microscopy. PU films made from PUD containing high BD as well as high DMPA concentrations have the best utility properties namely sufficient tensile properties and a very low swelling ability.

show abstract

Side Reactions in the Formation of Polyurethanes: Model Reactions Between Phenylisocyanate and 1-Butanol

Cited by 32 publications

References 5 publications

A Simple Method for the Quantification of Free Isocyanates on the Surface of Cellulose Nanocrystals upon Carbamation using Toluene Diisocyanate

A Simple Method for the Quantification of Free Isocyanates on the Surface of Cellulose Nanocrystals upon Carbamation using Toluene Diisocyanate

Reactivity of isocyanates with urethanes: Conditions for allophanate formation

Preparation and characterization of thermoplastic water‐borne polycarbonate‐based polyurethane dispersions and cast films

Contact Info

Product

Resources

About