| Nowadays,polyester materials,a kind of the most industrially important polymer materials,are widely used in biomedicine,electronics industry,building materials,automotive industry,ecological agriculture,and environmental protection.Among these materials,aliphatic polyesters are attracted much interest in a wide range of applications as a results of their biocompatibility,biodegradability,and recyclability aliphatic polyesters are the condensation polymefrom renewable resources.The most straightforward methods for preparation of rizations and the ring-opening polymerization(ROP).Very recently,cross-linked polymers with plasticity have already became an important research focus.Diselenide-containing polyester with multi-stimuli response,such as light,radiation,reduction and oxidation,became a hot point for their biomedical application.Current methods for synthesizing diselenide-containing polymers have some limitations.In this thesis,a new method for synthesizing diselenide-containing polyesters was explored.The details were summarized as the following(1)Diselenide compounds from a sequence alcholysis-oxidation reaction of selenolactoneThis strategy consists of a one-pot,two-step process with the generation of a selenol by in situ nucleophilic ring opening of ?-butyroselenolactone with alcohol,followed by the transformation of the obtained compounds to the corresponding diselenide through a spontaneous oxidation coupling reaction.The influence of catalysts,alcohol structures,and solvents on reaction efficiency was examined.After elaboration of this one-pot reaction,a series of diselenide compounds were synthesized.The structures of diselenide compounds were carefully characterized by 3C,77Se NMR,FT-IR,and HRMS.(2)Diselenide-containing polyesters from a sequence alcholysis-oxidation reaction of selenolactoneThese diselenide-containing polyesters were prepared by an in situ nucleophilic ring opening of ?-butyroselenolactone with a broad range of diols,following oxidation stepwise polymerization.Model reaction of alcoholysis-oxidation conjugation was built through a one-pot reaction of ?-butyroselenolactone and the structures of diselenide-containing polyesters were carefully characterized by 1H,13C,77Se NMR,FT-IR,HRMS,and SEC During this mild and efficient one-pot stepwise polymerization process,the terminal group of the polymer with a polyester/diselenide backbone could be adjusted by changing the ratio between the involved reagents.For example,when less than 2 equiv of selenolactone was used,Polyester with hydroxyl end groups was obtained.And the abundance of hydroxyl end group increases obviously when less than 2 equiv of selenolactone was used.This method provides opportunities for preparing different kinds of diselenide containing polyester with adjustable molecular weight and PDI,and the-OH terminal groups of the polyesters can serve as reaction sites for further functionalization with target agents.(3)Diselenide-containing polyester networks from a sequence alcholysis-oxidation reaction of selenolactoneThe networks were prepared by the in situ nucleophilic ring opening of ?-butyroselenolactone with triols,following oxidation stepwise polymerization.In the study,the glycerol was chose as a model compound for synthesis of cross-linked polyester with dynamic diselenide bonds.An insoluble but swellable polylers(PGOSe2)could be obtained when a ratio of the selenolactone with glycerol up to three was used.PGOSe2 presents good thermal and light response due to introducing of the dynamic diselenide bonds into the backbone of polyester.In addition,the diselenide-containing polyester networks showed fast self-healing ability and readily processed at mild temperature(70 OC)or under irradiation at room temperature.To explore the response performance of the diselenide-containing polyester,the self-healing and reprocess properties were determined by exposing a cut sample to UV light or at heating condition.After irradiation for 10 min in a UV box or heating for 20 min at 70?,the healing occurred. |
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