Modification of CNF‐Networks by the Addition of Small Amounts of Well‐Defined Rigid Cationic Nanolatexes

Abstract

Cellulose nanofibril (CNF)‐networks are modified by the addition of small amounts (below 10 wt%) of well‐defined cationic nanolatexes synthesized through reversible addition–fragmentation chain‐transfer‐mediated polymerization‐induced self‐assembly (PISA). Minute amounts of nanolatex inclusions lead to increased tensile and shear moduli, indicating that nanolatexes can act as bridging‐points between CNFs. At higher nanolatex content, this stiffening effect is lost, likely due to interactions between nanolatexes leading to plasticization. The influence of nanolatex content and size on interparticle distance is discussed and is used as a tool to understand the effects observed in macroscopic properties. Upon annealing, the stiffening effect is lost due to the softening of the nanolatexes, indicating that the core–shell morphology is a prerequisite for this effect. These systems form a versatile platform to develop fundamental insights into complex condensed colloidal systems, to ultimately aid in the development of new sustainable material concepts.

Bimodal nanolatexes prepared via polymerization-induced self-assembly: losing control in a controlled manner

“…In previous publications, nanolatexes of the same chemical composition, but with lower degrees of polymerization (DP) of MMA were monomodal and monodisperse as evaluated by dynamic light scattering (DLS) and field emission scanning electron microscopy (FE-SEM). 20,21 However, CCCPA has been reported to result in bimodal molecular weight distributions and subsequent loss of control of polymerization during PISA. 27 Although no such observation was made for the molecular weight distribution in the aforementioned studies, 20,21 in the current study, the bimodality was initially investigated via size exclusion chromatography (SEC) with THF as an eluent (Fig.…”

“…The preparation of the macroRAFT agents and their resulting nanolatexes was performed according to previous publications from our group and the amounts used for their synthesis are summarized in Table S1. † 20,21 The same synthetic protocol was employed for the preparation of cationically charged nanolatexes with a PTHFMA (T) core, referred to as D 25 -T 100 , D 25 -T 200 and D 25 -T 300 . More information regarding the kinetics of their polymerization and chemical composition can be found in the ESI ( parts 1 to 5).…”

“…This could be an additional reason why bimodal nanolatexes were not obtained in our previous studies, as higher DP of MMA, and thus size, have to be reached. 20,21 Additionally, the water solubility of the hydrophobic monomer, i.e., 15 g L −1 (ref. 30) and 1.8 g L −1 (ref.…”

“…All nanolatex-adsorbed QCM-D crystals were annealed in an oven at 150 °C for 5 h as described previously in the literature. 8,20,21 Afterwards, the samples were left for at least 24 h (RH 50%) before characterizing them with the CA and by FE-SEM.…”

“…Nanolatexes comprising blocks with the same chemical composition were also synthesized by replacing the CTPPA RAFT agent with 4-((((2-carboxyethyl)thio)carbonothioyl)thio)-4-cyanopentanoic acid (CCCPA). 20,21 In contrast to CTPPA, both the R-and Z-groups of CCCPA are composed of carboxylic acid units. Although monodisperse nanolatexes were prepared at a low DP of the hydrophobic PMMA core, surprisingly at higher DPs reproducible bimodal nanolatexes were obtained, which is the main topic of this study.…”