| Sustained-release film is a new type of drug carrier,which has many advantages,such as environment-friendly,safety,uniform release,high efficiency,and so on,and outstanding technical advantages as well as application prospects in the fields of medicine and modern agriculture.In this paper,polyvinyl alcohol(PVA)and starch(ST)blends were used as polymer raw materials,halloysite nanotubes(HNTs)and montmorillonite(MMT)were used as drug carriers,herbicide 2,4-dichlorophenoxyacetic acid(2,4-D)and atrazine(AT)were used as model drugs,and a series of nano-filler-supported drug-loaded films were prepared from the point of view of biodegradability,physical adsorption and the difference of target drug properties.The effects of HNTs and MMT on the mechanical properties,thermal stability,light transmission and swelling properties of PVA-ST composite films were investigated,and the release properties of PVA-ST drug-loaded films,as well as the effects of HNTs and MMT supported drug on the release properties,were studied.The main work is as follows:(1)PVA-ST/HNTs and PVA-ST/MMT composite films were prepared by using HNTs and MMT as fillers,respectively.And the structure and properties of the two composite films were studied.The results show that both HNTs and low weight MMT could uniformly disperse in their composite films to improve the water resistance of the composite films.HNTs could effectively improve the mechanical properties and thermal stability of its composite films,and low weight HNTs had little effect on the transparency of them.When the content of MMT was high,MMT's agglomeration occurs,which seriously affects the mechanical properties and transparency of its composite film.(2)PVA-ST/2,4-D sustained-release film was prepared by using PVA-ST composite film as the matrix material and 2,4-D as the model drug.And the structure and release properties of the sustained-release film were investigated.At the same time,two kinds of nano-filler-supported drugs sustained-release film were prepared by using HNTs and MMT-loaded 2,4-D as the functional filler,in order to obtain better controlled release performance.The results show that 2,4-D could uniformly disperse in the sustained-release film and slowly migrate to the surface of sustained-release membrane,playing the efficacy,so that the sustained-release film had good herbicidal effect.When the PVA-ST/2,4-D sustained-release film was immersed in water,the release rate of 2,4-D was high,and its release behavior was in accordance with the Fickian diffusion mechanism.In addition,both HNTs and MMT loaded 2,4-D could effectively delay the release of 2,4-D,and HNTs had a better effect on delaying the release of 2,4-D.(3)PVA-ST/AT sustained-release film and two kinds of nano-filler-supported herbicides sustained-release film were prepared by using herbicide atrazine as model drug,using HNTs and MMT-loaded atrazine as functional filler.And the structure and release properties of these sustained-release films were investigated emphatically.The results show that the release rate of atrazine was slow and coud keep release for more than 96 h,its release behavior was consistent with the Ritger-Peppas equation after the PVA-ST/AT sustained-release film immersed in water,which was a release mechanism combined with dissolution and diffusion.Besides,both HNTs and MMT-loaded atrazine could further delay the release of atrazine and increase the controlled-release properties of their sustained-release films,and the HNTs loaded atrazine had better ability to control the release of atrazine. |
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