Preparation and thermal stability of new cellulose-based poly(propylene imine) and poly(amido amine) hyperbranched derivatives

Divergent growth of poly(amidoamine) dendrimer-like branched polymers at the reducing end of cellulose nanocrystals

This paper presents the growth of dendritic polymers at the reducing ends of cellulose nanocrystals by the "grafting from" approach. We took advantage of the chemically differentiated ends of cellulose nanocrystals to specifically synthesize dendrimers at their reducing end by the divergent approach. We used acid-amine coupling reactions in aqueous media to synthesize the carboxylic acid- or amine-terminated poly(amidoamine) dendrimers. The growth of dendrimer generations was monitored by UV and FTIR spectroscopies, and we successfully introduced up to 4 generations. The dendrimer growth at reducing ends was demonstrated by the nanocrystal adsorption driven by the peripheral amino groups onto gold surfaces. Hence, the results from quartz crystal microbalance with dissipation (QCM-D) pointed to a rather upright orientation of the dendrimer-modified cellulose nanocrystals. As the generation increased, the adsorbed layers appeared to be more flexible, which demonstrated that the functionality at the reducing end can successfully tune the properties of cellulose nanocrystals.

Hyperbranched Polymers in Modifying Natural Plant Fibers and Their Applications in Polymer Matrix Composites-A Review

Natural plant fibers have been widely used in the agricultural and forest industries, and even in the automobile industry, especially for producing fiber reinforced polymer matrix composites. However, the low mechanical properties of composites remain the key problem in the applications. A hyperbranched polymer has lots of advantages such as low viscosity, high reactivity, and so on. Multireactive end groups of hyperbranched polymers are ideal for modifying natural plant fibers to achieve better interface bonding between a fiber and resin matrix. This manuscript reviews some research advances in hyperbranched-polymer-modified natural plant fibers and summarizes the applications of the modified fibers in polymer matrix composites with a particular focus on the chemical modification of fibers and interface bonding.