posted on 2021-05-27, 15:03authored byNiloofar Alipoormazandarani, Tobias Benselfelt, Luyao Wang, Xiaoju Wang, Chunlin Xu, Lars Wågberg, Stefan Willför, Pedram Fatehi
Lignin
is the richest source of renewable aromatics and has immense
potential for replacing synthetic chemicals. The limited functionality
of lignin is, however, challenging for its potential use, which motivates
research for creating advanced functional lignin-derived materials.
Here, we present an aqueous-based acid precipitation method for preparing
functional lignin nanoparticles (LNPs) from carboxymethylated
or carboxypentylated lignin. We observe that the longer grafted
side chains of carboxypentylated lignin allow for the formation
of larger LNPs. The functional nanoparticles have high tolerance against
salt and aging time and well-controlled size distribution with Rh ≤ 60 nm over a pH range of 5–11.
We further investigate the layer-by-layer (LbL) assembly of the LNPs
and poly(allylamine hydrochloride) (PAH) using a stagnation point
adsorption reflectometry (SPAR) and quartz crystal microbalance with
dissipation (QCM-D). Results demonstrate that LNPs made of carboxypentylated
lignin (i.e., PLNPs with the adsorbed mass of 3.02 mg/m2) form a more packed and thicker adlayer onto the PAH surface compared
to those made of carboxymethylated lignin (i.e., CLNPs with
the adsorbed mass of 2.51 mg/m2). The theoretical flux, J, and initial rate of adsorption, (dΓ/dt)0, analyses confirm that 22% of PLNPs and 20% of CLNPs
arriving at the PAH surface are adsorbed. The present study provides
a feasible platform for engineering LNPs with a tunable size and adsorption
behavior, which can be adapted in bionanomaterial production.