Cellulose-Based Films for Food Packaging Applications:Review of Preparation,Properties,and Prospects

Packaging is a food preservation technology widely used in the world.Naturally-sourced,biodegradable polymers are becoming increasingly popular in the food packaging sector.Packagingfilms prepared using cellulose as raw material would contribute to resource sustainability,but the difficulty of cellulose solubilization limits their further development.In view of this,a series of novel solvent systems(LiCl/DMAc,ILs,TBAH/DMSO,NMMO,alkali/urea solutions,metal-complex solutions)were used to prepare high-strength and high-performance cellulose-basedfilms;their characteristics and the mechanisms involved were investigated.Compositefilms prepared by blending cellulose with various polymers(synthetic polymers,natural polymers,proteins and enzymes,metal particles,and plant phenols)and their functional properties were also investigated.Problems with cellulose-basedfilms and the outlook for future research are discussed.It is hoped that in the near future high-performance,biodegradable and sustainably-produced cellulose-basedfilms will lead the food packaging industry into a new era and further promote the sustainable use of resources.

Glass-compatible and self-powered temperature alarm system by temperature-responsive organic manganese halides via backward energy transfer process

A pioneering glass-compatible transparent temperature alarm system self-powered by luminescent solar concentrators(LSCs) is reported.Single green-emitted organic manganese halides(OMHs) of PEA_(2)MnBr_(2)I_(2),which has a unique temperature-dependent backward energy transfer process from selftrapped state to^(4)T_(1)energy level of Mn,is used for triggering the temperature alarm.The LSC with redemitted CsPbI_(3)perovskite-polymer composite films on the glass substrate is used for power supply.The spectrally separated nature between the green-emitted OMHs for temperature alarm and red-emitted CsPbI3in LSC for power supply allows for probing the signal light of temperature-responsive OMHs without the interference of LSCs,making it possible to calibrate the temperature visually just by a self-powered brightness detection circuit with LED indicators.Taking advantage of LSC without hot spot effects plaguing the solar cells,as-prepared temperature alarm system can operate well on both sunny and cloudy day.