Preparation And Property Studies Of Dementholized Peppermint Fragrance Micro/nano-capsules With Polyurea Shell

With the improvement of living standards,the preference of flavor is becoming a trend and flavored products are increasingly enriched.However,most fragrances have strong volatility,and the sensitive components are prone to deteriorate,resulting in the change of flavor.So maintaining the flavor unchanged and extending valid time of fragrance are quite important for the application of fragrances.The microencapsulation of fragrances has functions of isolation and protection for the fragrances,which is prepared by coating the core material with polymer shell material.Meanwhile,compared with microcapsules,nanocapsules show the advantages of transparency,permeability,dispersion stability and compatibility due to the size effect,which make fragrance nanocapsules show unique application prospects in daily chemicals,food,functional textiles and so on.In this paper,dementholized peppermint(DP)fragrance microcapsules and nanocapsules were prepared through the interfacial polymerization with isocyanate monomer and different amine monomers,in which polyurea(PU)was formed as shell and fragrances was encapsulated as core materials.The influences of various factors on the formation,morphology and size of the fragrance micro/nano-capsules were investigated.The properties of the microcapsules and nanocapsules were also studied.The main contents of this paper include the following three aspects:(1)Preparation of DP microcapsules with PU as shell: In traditional preparation of polyurea microcapsules,the use of aromatic isocyanates usually leads to the formation of toxic aniline in the system.In this experiment the isophorone diisocyanate(IPDI),an aliphatic isocyanates,was used to avoid the problem effectively.By optimized the monomer and emulsifier,diethylenetriamine(DETA)was finally chosen as the amine monomer and polyvinyl alcohol(PVA)as the emulsifier.Then surface morphology,shell material composition,particle size and distribution,thermal stability,encapsulation efficiency,macro-morphology and dispersion stability of as prepared microcapsules were characterized.The results showed that the microcapsules prepared were spherical,and had good thermal stability.The slurry was prone to exhibit delamination after several days.and the mean particle size of the microcapsules decreased with the increase of the homogeneous rate.(2)Preparation of DP nanocapsules with PU as shell: Based on the preparation of the polyurea microcapsules,the preparation of nanocapsules with a high fragrance loading capacity was explored,which solved the problem that the microcapsule slurry was prone to exhibit delamination.By optimized the monomer,emulsifier and the composition of the oil phase,hexamethylene diamine(HMDA)was finally chosen as the amine monomer,sodium dodecyl sulfate(SDS)as the emulsifier,and 20 wt% caprylic / capric triglyceride(GTCC)as the oil phase regulator.Then core-shell structure and morphology,shell material composition,particle size and size distribution,thermal stability,encapsulation efficiency,macro-morphology,dispersion stability and transparency of as prepared nanocapsules were characterized.The results showed that the nanocapsules without and with 20 wt% GTCC both showed smooth spheres with visible core-shell structure.Moreover,it was confirmed that the addition of GTCC could greatly reduce the size of nanocapsules and also improved the size distribution.When the amount of core material was 20 wt% with loading of 16 wt% DP,the average size of nanocapsules was only 82.8 nm,with a low polydispersity of 0.19.The test demonstrated that the core material was successfully encapsulated and the nanocapsules all had good thermal stability,with encapsulation efficiency of about 80 %.The addition of GTCC as modifier could also greatly improve the dispersion stability and transparency of as prepared nanocapsules.(3)Application of fragrance micro/nano-capsules in textiles: The effects of adhesives on the adhesion of the micro/nano-capsules to the surfaces of the fibers were studied.The results showed that,using polyurethane as the adhesive,the flavored cotton fabrics had better effects with a certain degree of washing fastness,which kept good water resistence after several cycles of washing.