CNFs/ABPE-10 Composite Materails Prepared By Pickering Emulsion Technology And Its Impact On The Properties Of Foled Stubstrate

Flexible organic light-emitting diode(FOLED)is one of the most promising display technologies in the future,and the performanceof its substrate material are crucial factors affecting its device performance,service life and flexibility.In this paper,cellulose nanofibrils(CNFs)were prepared by mechanical grinding after the hemicellulose contents of the bleached bagasse pulp was regulated by different concentrations Na OH solution.Subsequently,combining Pickering emulsion technology with vacuum filtration and hot pressing,the CNFs as stabilizer were compounded with ABPE-10 to prepare multi-layer composite film with "brickmud" structure.The influence of ABPE-10 addition on the multi-layer structure and performance of the composite films was explored to evaluate its potential as a high-performance FOLED substrate.In order to further optimize the interfacial compatibility between CNFs and ABPE-10,the acetylation modification of CNFs was carried out.And then,the CNFs/ABPE-10 composite films were prepared by the same method in order to obtain high-performance FOLED substrate.The main conclusions are as follows:(1)The concentration of Na OH has a great influence on the hemicellulose contents and the crystallinity index of cellulose in bleached bagasse pulp.When the Na OH concentration was 5.0 w/v%(hemicellulose contents were 8.4%),the maximum crystallinity index of the cellulose was 62.85%.The crystal structure of cellulose treated with high alkali concentration(> 5.0 w/v%)would be converted from cellulose I to II.Partial reduction of hemicellulose contents(?8.4%)would be helpful to improve the yield of CNFs and the comprehensive performance of CNFs films such as the surface flatness,optical property,and mechanical property.(2)Based on ABPE-10 Pickering emulsion technology with CNFs as stabilizer,CNFs/ABPE-10 multi-layer composite films with "brick-mud" structure were successfully prepared through vacuum filtration and hot-pressing process.Compared with the impregnated composite films,the toughness(10.2%-12.0%)of the composite films prepared by Pickering emulsion technology was better.When the ABPE-10 addition was 2.16 g(the ratio of CNFs: ABPE-10 was1: 9),the CNFs/ABPE-10-2.16 composite film had the most perfect "brick-mud" structure and the best properties: transparency 87.6%,haze 6.0%,tensile strength51.6 MPa,elongation at break 12.0%,Young's modulus 1.2 GPa and CTE 14.4ppm/K.However,the fracture surfaces of the composite films showed different degrees of porosity,which was detrimental to the mechanical performance of the films and affected the service life and yield of the FOLED.(3)With the increase of the acetic anhydride addition,the acetylation substitution of hydroxyl in CNFs increased gradually,while the crystallinity index of CNFs decreased gradually.The CNFs/ABPE-10 composite films prepared with different acetylated CNFs through Pickering emulsion technology still had a "brick-mud" structure.When the acetylation substitution of hydroxyl was 0.53,the CNFs-0.53/ABPE-10 composite film had the most perfect "brick-mud" structure and the best properties: transparency 88.1%,haze 5.0%,tensile strength67.6 MPa,elongation at break 17.9%,Young's modulus 1.3 GPa and CTE 12.4ppm/K,which could be used as high-performance FOLED substrate.