Facile and efficient isocyanate microencapsulation via SDBS/PVP synergetic emulsion

Lu, Wei; Meng, Qingwei; Qin, Chuanrui; Li, Jinliang; Qi, Guansheng; Kong, Biao; Wang, Xinmeng

doi:10.1002/app.48045

Cited by 10 publications

(5 citation statements)

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“…In this approach, mixtures of diisocyanate compounds are used for a dual purpose, namely (i) for the formation of polyurea shell and (ii) as self-healing agents, taking advantage of the difference in reactivity of the selected R-NCOs. Typically, the highly reactive methylene diphenyl diisocyanate (MDI) (or prepolymers of MDI, the so-called PAPI) is used for polyurea shell formation and the less reactive aliphatic isophorone diisocyanate (IPDI) is encapsulated in the core as a releasable potential self-healing agent [ 10 , 11 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

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Controlling the Synthesis of Polyurea Microcapsules and the Encapsulation of Active Diisocyanate Compounds

Avdeliodi,

Tsioli,

Bokias

et al. 2024

Polymers

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The encapsulation of active components is currently used as common methodology for the insertion of additional functions like self-healing properties on a polymeric matrix. Among the different approaches, polyurea microcapsules are used in different applications. The design of polyurea microcapsules (MCs) containing active diisocyanate compounds, namely isophorone diisocyanate (IPDI) or hexamethylene diisocyanate (HDI), is explored in the present work. The polyurea shell of MCs is formed through the interfacial polymerization of oil-in-water emulsions between the highly active methylene diphenyl diisocyanate (MDI) and diethylenetriamine (DETA), while the cores of MCs contain, apart from IPDI or HDI, a liquid Novolac resin. The hydroxyl functionalities of the resin were either unprotected (Novolac resin), partially protected (Benzyl Novolac resin) or fully protected (Acetyl Novolac resin). It has been found that the formation of MCs is controlled by the MDI/DETA ratio, while the shape and size of MCs depends on the homogenization rate applied for emulsification. The encapsulated active compound, as determined through the titration of isocyanate (NCO) groups, was found to decrease with the hydroxyl functionality content of the Novolac resin used, indicating a reaction between NCO and the hydroxyl groups. Through the thorough investigation of the organic phase, the rapid reaction (within a few minutes) of MDI with the unprotected Novolac resin was revealed, while a gradual decrease in the NCO groups (within two months) has been observed through the evolution of the Attenuated Total Reflectance—Fourier-Transform Infrared (ATR-FTIR) spectroscopy and titration, due to the reaction of these groups with the hydroxyl functionalities of unprotected and partially protected Novolac resin. Over longer times (above two months), the reaction of the remaining NCO groups with humidity was evidenced, especially when the fully protected Acetyl Novolac resin was used. HDI was found to be more susceptible to reactions, as compared with IPDI.

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Section: Introductionmentioning

confidence: 99%

“…PAPI) is used for polyurea shell formation and the less reactive aliphatic isophorone diisocyanate (IPDI) is encapsulated in the core as a releasable potential self-healing agent [10,11,22].…”

Section: Introductionmentioning

confidence: 99%

Controlling the Synthesis of Polyurea Microcapsules and the Encapsulation of Active Diisocyanate Compounds

Avdeliodi,

Tsioli,

Bokias

et al. 2024

Polymers

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“…We previously reported on the encapsulation of isocyanate species with the commonly used interfacial polymerization technique, in polyurethane/polyurea (PU/PUa) shelled MCs, and the solvent evaporation method, in biodegradable shelled MCs [ 5 , 6 , 7 , 8 , 9 ]. Isocyanate microencapsulation is typically reported to be achieved using an oil-in-water (O/W) micro-emulsion system combined with the interfacial polymerization technique [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. It is a simple, reliable, well-studied, and low-cost process to produce isocyanate-loaded MCs.…”

Section: Introductionmentioning

confidence: 99%

“…The microencapsulation of isocyanate dates from 2008, with the encapsulation of monomeric isophorone diisocyanate (IPDI) [ 10 ], resourcing to a 2,4-TDI prepolymer, as a higher reactivity isocyanate, for the shell formation, and 1,4-butanediol as an extra active hydrogen (H) source and chain extender. Other isocyanates used for the shell formation, as well as other active H sources have been reported for the synthesis of IPDI loaded MCs, obtained using the referred technique [ 11 , 12 , 13 , 14 , 15 , 16 ]. Despite their advantages, the obtained MCs are not temperature responsive, have a poor shelf life and their shell exhibits none or low biodegradability.…”

Section: Introductionmentioning

confidence: 99%

Design of Experiment for Optimizing Microencapsulation by the Solvent Evaporation Technique

Loureiro,

Aguiar,

Santos

et al. 2023

Polymers

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We employed microemulsion combined with the solvent evaporation technique to produce biodegradable polycaprolactone (PCL) MCs, containing encapsulated isophorone diisocyanate (IPDI), to act as crosslinkers in high-performance adhesive formulations. The MC production process was optimized by applying a design of experiment (DoE) statistical approach, aimed at decreasing the MCs’ average size. For that, three different factors were considered, namely the concentration of two emulsifiers, polyvinyl alcohol (PVA) and gum arabic (GA); and the oil-to-water phase ratio of the emulsion. The significance of each factor was evaluated, and a predictive model was developed. We were able to decrease the average MC size from 326 μm to 70 µm, maintaining a high encapsulation yield of approximately 60% of the MCs’ weight, and a very satisfactory shelf life. The MCs’ average size optimization enabled us to obtain an improved distributive and dispersive mixture of isocyanate-loaded MCs at the adhesive bond. The MCs’ suitability as crosslinkers for footwear adhesives was assessed following industry standards. Peel tests revealed peel strength values above the minimum required for casual footwear, while the creep test results indicated an effective crosslinking of the adhesive. These results confirm the ability of the MCs to release IPDI during the adhesion process and act as crosslinkers for new adhesive formulations.

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“…17 –19 Yang et al 19 firstly synthesized isophorone diisocyanate (IPDI) microcapsules via interfacial polymerization of toluene diisocyanate prepolymers in oil-in-water emulsion, and numerous isocyanates encapsulation microcapsules have been reported till now. 20 –24 Wang et al 25 discussed the preparation of microcapsules filled with IPDI in a sodium dodecyl benzene sulfonate (SDBS) aqueous solution and proved that the mechanical properties of the microcapsule shells could be adjusted by the introduction of oxygen plasma treated carbon nanotubes. Di Credico et al 16 discussed the effects of single layer and bilayer shells on the synthesis of microcapsules containing IPDI in a gum arabic emulsion system and found that double layered capsules showed 50–70 wt% core content, well dispersed, and excellent corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Optimized synthesis of isocyanate microcapsules for self-healing application in epoxy composites

Sun

Wang

Dong

et al. 2020

High Performance Polymers

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Microcapsules containing isophorone diisocyanate were fabricated in oil-in-water emulsion. The emulsification effect of different emulsifiers during the capsule synthesis was systematically investigated by optical microscope. Three kinds of shell materials were discussed to obtain the high core content, smooth-surfaced, and robust capsule by scanning electronic microscope and Fourier transform infrared spectroscopy. Self-healing performance of corresponding self-healing epoxy composites was fully evaluated by accelerated corrosion test and mechanical test. The results demonstrated that high core content and smooth-surfaced capsules with dense composite shell could be synthesized in polyvinyl alcohol emulsion, and the core content of the optimized capsules was determined as 71.3–84.6 wt% at the capsule size from 35 µm to 154 µm. In addition, the optimized capsules had good processing properties and the corresponding self-healing epoxy composites exhibited excellent core release and self-healing performance.

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Facile and efficient isocyanate microencapsulation via SDBS/PVP synergetic emulsion

Cited by 10 publications

References 50 publications

Controlling the Synthesis of Polyurea Microcapsules and the Encapsulation of Active Diisocyanate Compounds

Controlling the Synthesis of Polyurea Microcapsules and the Encapsulation of Active Diisocyanate Compounds

Design of Experiment for Optimizing Microencapsulation by the Solvent Evaporation Technique

Optimized synthesis of isocyanate microcapsules for self-healing application in epoxy composites

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