Preparation and characterization of waterborne polyurethane based on diphenylmethane diisocyanate‐50

We prepared a temperature-responsive polyurethane (PU) film with reversible visible light transmittance change, which was opaque at room temperature and became transparent when the temperature rised. The PU film has very low visible light transmittance of 1.4% at room temperature. At 45 C, the PU film has relatively high transmittance of 66.7% looking translucent. When the temperature goes to 50 C or above, the transmittance is more than 80% and the PU film is transparent. The reason for this interesting phenomenon about visible light transmittance change was illustrated by polarizing optical microscope and differential scanning calorimetry. While ultraviolet light transmittance of the PU film is very low at all time. Moreover, this PU film has excellent mechanical performance in a wide temperature range. We suppose this PU film has potential applications in many fields such as tunable optical devices or coating materials with smart temperature responsivity.

Section: Resultsmentioning

confidence: 99%

A temperature‐responsive polyurethane film with reversible visible light transmittance change and constant low UV light transmittance

Xiao

Liu

et al. 2018

“…These microcapsules ensure high encapsulation efficiency and long‐term release for the core materials. Moreover, as fabricated from IPDI and pentaerythrotol, the shell is a polyurethane material, which owns good mechanical strength and water resistance resulting in excellent protection for the core materials …”

Section: Resultsmentioning

confidence: 99%

Preparation of monosultap‐polyurethane microcapsules in an inverse emulsion through interfacial polymerization

Wang

Xiao

2019

Self Cite

In this study, we prepared monosultap microcapsules in an inverse emulsion through interfacial polymerization for the first time. The microcapsules are spherical pellets with intact and smooth shell and have a narrow particle size distribution with an average size of about 2.35 μm. More importantly, our microcapsules have excellent thermal stability with a starting decomposition temperature of 233.1 C, high encapsulation efficiency of 81.9% as well as long-term slow release of monosultap under different conditions. In addition, the shell of the microcapsules can degrade completely in the natural condition, avoiding the pollution to the environment. It can be believed that our microcapsules will show good service performance if employed in agricultural industry.

“…The molecular weight gradually increased and each macromolecular chain length of the PUIs tended to be nonuniform, and polydispersity index also increased. However, when R value was greater than 1.04, the PUIs were difficult to dissolve in acetone, which resulted from the reaction of the highly reactive MDI‐50 with secondary amino groups of carbamate esters and formed crosslinked network structures because the NCO groups were excessive relative to the hydroxyl groups …”

Section: Resultsmentioning

confidence: 99%

Preparation of polyurethane ionomers by reactive extrusion and dispersions containing sulfonate groups and polyethylene glycol segments

Sun

2019

A synthesis method of polyurethane ionomers (PUIs) and anionic/nonionic polyurethane dispersions (PUDs) is introduced in this article. PUIs were synthesized in twin‐screw extruder without organic solvent. PUIs were then dissolved in acetone and dispersed in water. The PUDs were obtained after distilling off acetone and the solid content of PUDs was about 55% and had excellent stability. PUDs obtained were mainly used as adhesives. PUIs were synthesized from poly(1,4‐butylene adipate glycol) (PBA) as soft segments, 1,4‐butanediol (BDO) and diphenylmethane diisocyanate‐50 (MDI‐50) as hard segments, poly(ethylene glycol) methyl ether (MPEG) and polyether diol‐containing sulfonate (SPPG) as hydrophilic monomers, and dibutyltin dilaurate (DBTDL) as catalyst. The particle size, viscosity, and adhesive properties of the PUDs were measured and the results indicated that PUDs obtained have excellent stability and adhesive properties, such as the maximum initial peel strength and T‐peel strength were 2.38 and 11.82 N mm−1, respectively. The thermal properties, tensile stress–strain, and water resistance of the PUIs films were also characterized. The test results showed that films have good thermal properties and water resistance properties, and some typical characteristics of crystalline polymers were revealed in the tensile stress–strain curves. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47719.