Xyloglucan-Functional Latex Particles via RAFT-Mediated Emulsion Polymerization for the Biomimetic Modification of Cellulose

Abstract

Herein, we report a novel class of latex particles composed of a hemicellulose, xyloglucan (XG), and poly(methyl methacrylate) (PMMA), specially designed to enable a biomimetic modification of cellulose. The formation of the latex particles was achieved utilizing reversible addition-fragmentation chain transfer (RAFT) mediated surfactant-free emulsion polymerization employing XG as a hydrophilic macromolecular RAFT agent (macroRAFT). In an initial step, XG was functionalized at the reducing chain end to bear a dithioester. This XG macroRAFT was subsequently utilized in water and chain extended with methyl methacrylate (MMA) as hydrophobic monomer, inspired by a polymerization-induced self-assembly (PISA) process. This yielded latex nanoparticles with a hydrophobic PMMA core stabilized by the hydrophilic XG chains at the corona. The molar mass of PMMA targeted was varied, resulting in a series of stable latex particles with hydrophobic PMMA content between 22 and 68 wt % of the total solids content (5-10%). The XG-PMMA nanoparticles were subsequently adsorbed to a neutral cellulose substrate (filter paper), and the modified surfaces were analyzed by FT-IR and SEM analyses. The adsorption of the latex particles was also investigated by quartz crystal microbalance with dissipation monitoring (QCM-D), where the nanoparticles were adsorbed to negatively charged model cellulose surfaces. The surfaces were analyzed by atomic force microscopy (AFM) and contact angle (CA) measurements. QCM-D experiments showed that more mass was adsorbed to the surfaces with increasing molar mass of the PMMA present. AFM of the surfaces after adsorption showed discrete particles, which were no longer present after annealing (160 °C, 1 h) and the roughness (Rq) of the surfaces had also decreased by at least half. Interestingly, after annealing, the surfaces did not all become more hydrophobic, as monitored by CA measurements, indicating that the surface roughness was an important factor to consider when evaluating the surface properties following particle adsorption. This novel class of latex nanoparticles provides an excellent platform for cellulose modification via physical adsorption. The utilization of XG as the anchoring molecule to cellulose provides a versatile methodology, as it does not rely on electrostatic interactions for the physical adsorption, enabling a wide range of cellulose substrates to be modified, including neutral sources such as cotton and bacterial nanocellulose, leading to new and advanced materials.

Biomimetic adsorption of zwitterionic–xyloglucan block copolymers to CNF: towards tailored super-absorbing cellulose materials

“…1. The XG-RAFT was synthesised according to previous reports, 20 and used to prepare XG-b-PSBMA block copolymers, whilst 4-cyano-4(phenylcarbothioylthio) pentanoic acid (CTP) was used to prepare the reference PSBMA homopolymers.…”

“…This result was not expected as it was hypothesised that the longer block copolymer; XG-b-PSBMA 710 , would adsorb a higher mass to the CNF surface than the shorter block copolymer; XG-b-PSBMA 266 , as has been shown in our previous work on block copolymers 42,43 and latex nanoparticles. 20,44 It may be that this polymer, which is water soluble and does not form micelles in aqueous solution, shields the adsorbing block rather than exposes it, as is the case with previously studied amphiphilic block copolymers, 42 which then would cause the unexpected low adsorption. Furthermore, in these QCM-D experiments the initial mass of CNF adsorbed to the surface was different between the two samples.…”

“…The xyloglucan macromolecular RAFT agent (XG-RAFT), bearing a dithiobenzoate moiety, was prepared as previously described, 20 the synthesis of which relies on the reductive amination of the XG reducing chain end, 49 followed by coupling the RAFT chain transfer agent using EDC chemistry, and had an average molecular weight of 17. The bre source used was a neverdried sowood dissolving pulp kindly donated by Domsjö Fabriker AB,Örnsköldsvik, Sweden.…”

Exploiting poly(ɛ‐caprolactone) and cellulose nanofibrils modified with latex nanoparticles for the development of biodegradable nanocomposites

“…The use of tailor‐made copolymers for the surface modification of cellulose, in particular CNF, through physical adsorption is becoming an active domain of research . The common denominator in most of the studies is the use of a cationic anchoring block composed of for example, poly( N , N ‐[dimethylamino]ethyl methacrylate) (PDMAEMA), which can then be copolymerized with polystyrene (PS) , poly(di[ethylene glycol] methyl ether methacrylate) , polybutadiene (PB) , or poly(methyl methacrylate) (PMMA) to mention a few examples.…”

Fucoidan-Mimetic Glycopolymers : Synthesis and Biomedical Applications

“…Type I are glycopolymers in which a polysaccharide has been coupled to a synthetic polymer [52][53][54]. In type II glycopolymers, a modified polysaccharide has been used either as an initiator or as a chain transfer agent (CTA) to synthesize polymers with the modified polysaccharide as platform [55][56][57][58][59][60][61]. Type III glycopolymers utilizes synthetic polymers with pendant functional groups to which, predominantly, mono-or disaccharides are coupled covalently through, e.g., 'click-' and thiol chemistries or nucleophilic acyl substitution [45,46,49,51,62].…”