Preparation And Characterization Of Photo-and Chemo-Degradable Polystyrene

Polystyrene is polymerized from styrene monomer.Polystyrene has been widely used in industry and our daily life,due to its advantages of large output,wide product and wide application range.However,polystyrene also has its own the shortcomings can not be ignored,especially the discarded polystyrene can lead to environmental pollution due to its non-degradability under environmental conditions.The existing polystyrene materials have been difficult to meet the requirements of modern society on the issue of environmental pollution and the increasing demand for environmentally friendly materials.Therefore,it is highly desirable to design and prepare degradable PS for eco-environmental issues and sustainable development.In this paper,new strategies have been proposed for preparation of degradable polystyrenes by the combination of radical polymerization and polyesterification.The main content is depicted as follows:1.The strategy is based on the highly efficient esterification reaction of dicarboxylic acid,4,4'-azobis(4-cyanovaleric acid),with organic dihalide,2-nitro-1,3-phenylene bis(methylene-2-chloroacetate)and free radical polymerization of styrene.Multiblock polystyrenes containing o-nitrobenzyl ester and ester moieties in the main chain were successfully synthesized by one-pot approach.Moreover,the photodegradation behavior of the multiblock PS in THF solution and in solid state was examined under UV irradiation at room temperature in air atmosphere.The results demonstrated that the multiblock polystyrenes could be degraded into separate PS blocks not only by UV light,but also by hydrolysis of the ester groups.In addition,the incorporation of o-nitrobenzyl units into the backbone of PS has no obvious influence on the thermal stability.2.A new macromolecular chain transfer agent was designed and synthesized by polyesterfication of the monomer with dicarboxylic groups,S,S'-bis(?,?'-dimethyl-?''-acetic acid)-trithiocarbonate and the monomer with diiodine groups,1,3-bis(iodomethyl)-2-nitrobenzene.Then,multiblock polystyrenes containing o-nitrobenzyl ester and trithiocarbonate moieties as photosensitive units in the main chain were successfully synthesized by RAFT polymerization of styrene in the presence of the macromolecular chain transfer agent.Moreover,the photodegradation behavior of the multiblock PS in THF solution and in solid state was examined under UV irradiation at room temperature in air atmosphere.The structure and molecular weight of the macromolecular chain transfer agent and the multiblock polystyrenes were characterized by 1H-NMR spectroscopy and GPC.The photodegradation and chemical degradation behavior were investigated through 1H-NMR spectra?UV-Vis and GPC analyses.The results demonstrated that the multiblock polystyrenes could be degraded into separate PS blocks not only by UV light,but also by hydrolysis or amiolysis of the ester and trithiocarbonate groups.In addition,thermal properties of the multiblock PS were measured by DSC and TGA under a nitrogen atmosphere.The result of thermal analysis indicated that the thermal properties of the multiblock PS are very similar to those of conventional polystyrene.