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Recycling the polymer material from the waste has a great advantage in reducing the cost of the biodegradable hot melt adhesive and solving environmental problems. Cellulose diacetate obtained from the acid hydrolysis of discarded cellulose triacetate‐based cinematographic films was blended with low molecular weight partially saponified polyvinyl acetate. The degree of substitution of cellulose diacetate and the degree of saponification of partially saponified polyvinyl acetate to obtain the binary blends having excellent compatibility were determined by FTIR and DSC. TGA showed that these blends have sufficient thermal stability for hot melt adhesive applications. The viscoelastic properties of the blends were evaluated by DMA and melt viscosity. The shear strength and the biodegradability of the final hot melt adhesive were examined according to the amount of cellulose diacetate in the blends. The results indicate that adding 20% of cellulose diacetate can reduce the cost of partially saponified polyvinyl acetate ‐based hot melt adhesive while improving the adhesive strength.

Recently, hole-transport material (HTM)-free mesoporous perovskite solar cells (PSCs) with carbon electrodes have attracted great attention due to their high stability and low fabrication cost. However, the power conversion efficiency of HTM-free PSCs with carbon electrodes is not high enough due to the lack of a proper perovskite coating method. In this work, very uniform and dense perovskite films were prepared by the acid−base reaction between the dimethylammonium lead iodide (DMAPbI 3 , so-called HPbI 3 ) solid and the methylamine (CH 3 NH 2 ) gas. The results showed that the contact between the perovskite layer and the porous carbon layer was improved by increasing the concentration of the DMAPbI 3 solution, possibly due to the enhancement of pore filling in the perovskite layer within the mesoporous structure and the increase of the crystal size of the perovskite layer. It was also found that the solid−gas reaction time between DMAPbI 3 and CH 3 NH 2 had a serious influence on the crystallization of the perovskite film. The fabricated HTM-free mesoporous PSCs with carbon electrodes demonstrated a high efficiency of 15.04%, together with a decrease in device hysteresis and improvement in device stability.

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