Investigations Of The Stability And Interfacial Viscoelasticity Of The Foams Stabilized By Silk Fibroin

In this thesis,novel foams with strong interfacial stability and good biocompatibility were prepared using silk fibroin extracted from natural Bombyx mori cocoon shells.Through the investigation of interfacial rheological behaviors of silk fibroin at the air/water interface and the stability of the foams stabilized by silk fibroin,the influence of silk fibroin concentration on the interfacial viscoelasticity,foaming ability and foam stability of the silk fiborin at the air/water interface was discussed,the relationship between interfacial rheological characteristics and foam stability for the silk fibroin was obtained,and the control and analysis methods for the foam stability of silk fibroin was revealed.This study will provide new idea for the preparation and investigations of the silk fibroin foams and important theoretical foundation for the applications of silk fibroin foams in drug delivery,food industry as well as cosmetics.At the beginning,the silk fibroin aqueous solution was prepared through degumming in alkali solution,dissolution in LiBr solution and dialysis against deionized water.A series of silk fibroin foams with different silk fibroin concentration were prepared using buffer solution,and the stability of these foams was investigated and the influence of silk fibroin concentration on the stability of the silk fibroin foams was also analyzed.Afterwards,by using ellipsometry,profile analysis tensiometerand stress-controlled rheometer,the interfacial dilatational rheology and interfacial shear rheology behaviors of the silk fibroin at the air/water interface were investigated,the influence of silk fibroin concentration on the interfacial rheological characteristics of silk fibroin was analyzed,and the interfacial viscoelasticity and interfacial adsorption dynamics of silk fibroin were discussed.Finally,the future expectations for the investigations of silk fibroin were brought forward.The results showed that silk fibroin has good surface activity and can stabilize the air/water interface to obtain stably foams.With the increase of silk fibroin concentration,the structural arrangements of silk fibroin molecules at the air/water interface becomes more compact,the thickness,storage modulus and toughness of the interfacial silk fibroin layers adsorbed at the air/water interface are increased,and the stability of the silk fibroin foams is also improved.The stability of silk fibroin foams intimately relates to the adsorption dynamics and interfacial viscoelasticity of the silk fibroin at the air/water interface.