Fabrication of bio-based composite fillers based on the combination of crystallization and gelation

Abstract

Fillers are the second major component of paper, and can give certain properties to paper-based materials. However, if we want to use fillers to develop novel functional paper-based materials, some challenges have to be considered such as filler functionality, retention rate, and the negative effects. To meet with these challenges, the present work proposed a fabrication concept of bio-based composite fillers. The concept combined the crystallization of target component and the gelation process of chitosan (CS), simultaneously. The gels carried and protected the crystals, and served as bridge between crystal of fillers and the paper matrix. To explore and demonstrate the concept, CaCO3/CS bio-based composites were successfully fabricated. The composite fillers were further optimized to be suitable for paper-making. The fabrication concept could significantly increase the filler retention rate (up to 90.57 %), the filler bondability (increased over 10 times) and the mechanical strength (59.7 % higher than paper without fillers). The fabrication concept was also applicable to functional materials. Zeolitic imidazolate framework-8 (ZIF-8)/CS composite fillers were successfully fabricated, and endowed the resulted paper with high surface area (180 times higher than pure cellulose paper). This fabrication concept would be useful to develop functional paper-based materials in the future.