Rapid Synthesis of Polymer-Grafted Cellulose Nanofiber Nanocomposite via Surface-Initiated Cu(0)-Mediated Reversible Deactivation Radical Polymerization

Designing mechanically robust one-component nanocomposites via hyperbranched cellulose nanofibril grafted vegetable oil polymers

Achieving effective interfacial compatibility between hydrophilic cellulose nanofibrils (CNFs) and hydrophobic vegetable oil polymers (VOPs) remained a significant challenge. To address this issue, we developed a one-component nanocomposite (OCN) based on hyperbranched CNF-grafted VOPs. Rigid precursor initiator poly (vinylbenzyl chloride) (PVBC) was first grafted onto the CNF surface via phase-transfer catalysis, forming a branched macroinitiator (CNF-g-PVBC) with chlorine contents ranging from 4.4 to 9.1 wt%. Subsequently, vegetable oil based monomers (lauryl methacrylate, LMA) were directly grafted onto CNF-g-PVBC through sacrificing initiator-free surface-initiated atom transfer radical polymerization (SI-ATRP). Finally, a hyperbranched CNF-based one-component nanocomposite (OCN-CVOP) was successfully prepared. Nanoscale infrared spectroscopy and microscopy confirmed the highly uniform morphology of the OCN-CVOP films, highlighting the superior dispersion of CNFs within the VOP matrix. Notably, compared to pure VOPs, OCN-CVOP exhibited remarkably low glass transition temperature (∼-15 °C) and reduced viscosity, which was attributed to the hyperbranched architecture. Even at LMA contents as high as ∼70 wt%, OCN-CVOP demonstrated excellent mechanical performance, achieving a tensile strength of 3.6 ± 0.2 MPa and a toughness of 21.5 ± 2.9 MJ/m3. This innovative design successfully addressed the mechanical limitations of conventional VOPs, offering a sustainable approach for developing environmentally friendly, high-performance VOP materials with diverse application potential.

Enhancing strength and toughness simultaneously: Diblock-grafted cellulose nanofiber one-component nanocomposites

To overcome the drawbacks of homopolymer-grafted CNF one-component nanocomposites, a range of diblock-grafted cellulose nanofiber (CNF), CNF-g-(polybutyl acrylate-b-polymethyl methacrylate)s were synthesized through reversible-deactivation radical polymerization (RDRP) methods. The chemical structures and ratios between the two blocks were confirmed, with surface-grafted CNF observed as submicron particles. Both thermal and thermodynamic analysis revealed two glass transition temperatures (Tg) in the diblock-grafted CNF, and phase-separated morphology was observed in the nanocomposites. The densely grafted CNF displayed island structures, while sparsely grafted samples transitioned into continuous structure. Thermodynamic analysis showed that the diblock-grafted CNF nanocomposites maintained mechanical properties at high temperatures. These nanocomposites demonstrated robust strength and toughnes, with tensile strength reaching as high as 43.7 ± 1.6 MPa and elongation at break of 70.3 ± 16.2 %. Moreover, while densely grafted CNF exhibited higher modulus and strength, whereas sparsely grafted CNF displayed behavior more reminiscent of thermoplastic elastomers, indicated by lower modulus and higher elongation.

Nanocellulose-stabilized nanocomposites for effective Hg(II) removal and detection: a comprehensive review

Mercury pollution, with India ranked as the world's second-largest emitter, poses a critical environmental and public health challenge and underscores the need for rigorous research and effective mitigation strategies. Nanocellulose is derived from cellulose, the most abundant natural polymer on earth, and stands out as an excellent choice for mercury ion remediation due to its remarkable adsorption capacity, which is attributed to its high specific surface area and abundant functional groups, enabling efficient Hg(II) ion removal from contaminated water sources. This review paper investigates the compelling potential of nanocellulose as a scavenging tool for Hg(II) ion contamination. The comprehensive examination encompasses the fundamental attributes of nanocellulose, its diverse fabrication techniques, and the innovative development methods of nanocellulose-based nanocomposites. The paper further delves into the mechanisms that underlie Hg removal using nanocellulose, as well as the integration of nanocellulose in Hg detection methodologies, and also acknowledges the substantial challenges that lie ahead. This review aims to pave the way for sustainable solutions in mitigating Hg contamination using nanocellulose-based nanocomposites to address the global context of this environmental concern.

Tunable poly(lauryl methacrylate) surface grafting via SI-ATRP on a one-pot synthesized cellulose nanofibril macroinitiator core as a shear-thinning rheology modifier and drag reducer

The optimally one-pot synthesized 2-bromoproponyl esterified cellulose nanofibril (Br-CNF) has been validated as a robust macroinitiator for self-surface-initiated atom transfer radical polymerization (SI-ATRP) of lauryl methacrylate (LMA) in tunable graft lengths and high conversions of up to 92.7%. SI-ATRP of LMA surface brushes on Br-CNF followed first order kinetics in lengths at up to 46 degree of polymerization (DP) based on mass balance or 31 DP by solution-state 1H NMR in DMSO-d6. With increasing PLMA graft lengths, Br-CNF-g-PLMA cast films exhibited increasing hydrophobicity with water contact angles from 80.9° to 110.6°. The novel Br-CNF-g-PLMA exhibited dual shear thinning behavior of the Br-CNF core as evident by n < 1 flow behavior index and drag reducing properties of PLMA grafts with increased viscosity at up to 21 071×. Br-CNF-g-PLMA with 46 DP could be fully dispersed in silicon pump oil to function as a drag reducer to enhance viscosity up to 5× at 25, 40, and 55 °C. The novel macroinitiator capability of Br-CNF in SI-ATRP of vinyl monomers and the bottlebrush-like LMA surface grafted Br-CNF as highly effective viscosity modifier and drag reducer further demonstrate the versatile functionality of Br-CNF beyond hydrophobic coatings and reactive polyols previously reported.

Synthesis and Applications of Hybrid Polymer Networks Based on Renewable Natural Macromolecules

Macromolecules obtained from renewable natural sources are gaining increasing attention as components for a vast variety of sustainable polymer-based materials. Natural raw materials can facilitate continuous-flow production due to their year-round availability and short replenishment period. They also open new opportunities for chemists and biologists to design and create "bioreplacement" and "bioadvantaged" polymers, where complex structures produced by nature are being modified, upgraded, and utilized to create novel materials. Bio-based macromonomers are expected not only to compete with but to replace some petroleum-based analogs, as well. The development of novel sustainable materials is an ongoing and very dynamic process. There are multiple strategies for transforming natural macromolecules into sophisticated value-added products. Some methods include chemical modification of macromolecules, while others include blending several components into one new system. One of the most promising approaches for incorporating renewable macromolecules into new products is the synthesis of hybrid networks based on one or more natural components. Each one has unique characteristics, so its incorporation into a network brings new sustainable materials with properties that can be tuned according to their end-use. This article reviews the current state-of-the-art and future potential of renewable natural macromolecules as sustainable building blocks for the synthesis and use of hybrid polymer networks. The most recent advancements and applications that involve polymers, such as cellulose, chitin, alginic acid, gellan gum, lignin, and their derivatives, are discussed.

Thermoformable and transparent one-component nanocomposites based on surface grafted cellulose nanofiber

One-component nanocomposites based on poly(methyl methacrylate)(PMMA) and polystyrene (PS) grafted cellulose nanofiber (CNF) with high polymer graft percentage were fabricated. At relative ambient conditions, less active vinyl monomer, MMA, and styrene were grafted from CNF via surface-initiated Cu(0)-mediated reversible deactivation radical polymerizations (RDRP), and PMMA/PS grafted CNFs could reach a graft percentage as high as 7550 % and 3530 %, respectively. The one-component composite films were manufactured by simple hot-pressing subsequentially. Optical transparency, thermal stability, and glass transition temperature of one-component nanocomposites were enhanced dramatically in contrast with the bicomponent nanocomposite. The uniform fracture surface confirmed the uniform dispersity by morphological observation. Mechanical tests indicated that break elongation and tensile strength ascended notably, and tensile modulus slightly descended as the graft percentage increased for PS and PMMA grafted CNF one-component composite. It was concluded that for glassy graft chains, obtaining one-component nanocomposites with high enough graft chain length was essential to achieve moderated mechanical performance without compromising optical properties and thermal manufacturing ability.

Thermal Stability of Polycaprolactone Grafted Densely with Maleic Anhydride Analysed Using the Coats-Redfern Equation

The plastic waste problem has recently attracted unprecedented attention globally. To reduce the adverse eff ects on environments, biodegradable polymers have been studied to solve the problems. Poly(ε-caprolactone) (PCL) is one of the common biodegradable plastics used on its own or blended with natural polymers because of its excellent properties after blending. However, PCL and natural polymers are difficult to blend due to the polymers' properties. Grafted polymerization of maleic anhydride and dibenzoyl peroxide (DBPO) with PCL is one of the improvements used for blending immiscible polymers. In this study, we first focused on the effects of three factors (stirring time, maleic anhydride (MA) amount and benzoyl peroxide amount) on the grafting ratio with a maximum value of 4.16% when applying 3.000 g MA and 1.120 g DBPO to 3.375 g PCL with a stirring time of 18 h. After that, the grafting condition was studied based on the kinetic thermal decomposition and activation energy by the Coats-Redfern method. The optimal fitting model was confirmed by the determination coefficient of nearly 1 to explain the contracting volume mechanism of synthesized PCL-g-MA. Consequently, grafted MA hydrophilically augmented PCL as the reduced contact angle of water suggests, facilitating the creation of a plastic-biomaterial composite.

Reactive Cellu-mers-A Novel Approach to Improved Cellulose/Polymer Composites

In this paper, we describe a novel method for preparation of polymer composites with homogeneous dispersion of natural fibers in the polymer matrix. In our approach, Williamson ether synthesis is used to chemically modify cellulose with polymerizable styrene moieties and transform it into a novel multifunctional cellu-mer that can be further crosslinked by copolymerization with styrene. Reactions with model compounds (cellobiose and cellotriose) successfully confirm the viability of the new strategy. The same approach is used to transform commercially available cellulose nanofibrils (CNFs) of various sizes: Sigmacell and Technocell™ 40, 90 and 150. The styrene-functionalized cellulose oligomers and CNFs are then mixed with styrene and copolymerized in bulk at 65 °C with 2,2'-azobisisobutyronitrile as initiator. The resulting composites are in a form of semi-interpenetrating networks (s-IPN), where poly(styrene) chains are either crosslinked with the uniformly dispersed cellulosic component or entangled through the network. Non-crosslinked poly(styrene) (31-41 w%) is extracted with CHCl3 and analyzed by size-exclusion chromatography to estimate the extent of homopolymerization and reveal the mechanism of the whole process. Electron microscopy analyses of the networks show the lack of cellu-mer agglomeration throughout the polymer matrix. The homogeneous distribution of cellulose entities leads to improved thermal and mechanical properties of the poly(styrene) composites compared to the physical mixtures of the same components and linear poly(styrene) of similar molecular mass.

Polymeric Nanofibers of Various Degrees of Crosslinking as Fillers in Poly(styrene-stat-n-butyl acrylate) Nanocomposites: Overcoming the Trade-Off between Tensile Strength and Stretchability

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