Synthesis of Cellulose-graft-Poly(N,N-dimethylamino-2-ethyl methacrylate) Copolymers via Homogeneous ATRP and Their Aggregates in Aqueous Media

Synthesis of thermally and pH-responsive poly(2-(dimethylamino)ethyl methacrylate)-based hydrogel reinforced with cellulose nanocrystals for sustained drug release

Hydrogels are widely employed in biomedical applications due to their high swelling potential, tailored mechanical properties, biocompatibility, and ability to incorporate drugs to modify their release behavior. This study explored the synthesis of dual stimuli-responsive composite hydrogels by combining poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) with 4, 8, and 12 % (w/w) of cellulose nanocrystals (CNC) through in-situ free-radical polymerization, modifying their properties for topical anti-inflammatory release. Although PDMAEMA-based hydrogels have been known for their responsiveness to pH and temperature stimuli, which are useful for modulating the release profile of drugs, their use as a matrix for anti-inflammatory topical applications remains unexplored. Thus, a comprehensive analysis of CNC concentration's impact on PDMAEMA-based hydrogel structure and physicochemical properties is provided. The incorporation of ibuprofen as an anti-inflammatory model was assessed, providing insights into the potential of these composite hydrogels for sustained drug delivery applications. Overall, the hydrogels exhibited homogenous CNC dispersion, with gel fraction higher than 70 % and ibuprofen load higher than 90 %. The rise in CNC concentration led to an increase hydrogel stiffness. Finally, the CNC incorporation also modified the ibuprofen release to a more sustained profile, following the Peppas-Sahlin model, which may be attractive for developing pharmaceutical devices for different therapeutical scenarios.

Photoinduced Metal-Free Atom Transfer Radical Polymerization for the Modification of Cellulose with Poly(N-isopropylacrylamide) to Create Thermo-Responsive Injectable Hydrogels

Photoinduced metal-free ATRP has been successfully applied to fabricate thermo-responsive cellulose graft copolymer (PNIPAM-g-Cell) using 2-bromoisobuturyl bromide-modified cellulose as the macroinitiator. The polymerization of N-isopropylacrylamide (NIPAM) from cellulose was efficiently activated and deactivated with UV irradiation in the presence of an organic-based photo-redox catalyst. Both FTIR and 13C NMR analysis confirmed the structural similarity between the obtained PNIPAM-g-Cell and that synthesized via traditional ATRP methods. When the concentration of the PNIPAM-g-Cell is over 5% in water, it forms an injectable thermos-responsive hydrogel composed of micelles at 37 °C. Since organic photocatalysis is a metal-free ATRP, it overcomes the challenge of transition-metal catalysts remaining in polymer products, making this cellulose-based graft copolymer suitable for biomedical applications. In vitro release studies demonstrated that the hydrogel can continuously release DOX for up to 10 days, and its cytotoxicity indicates that it is highly biocompatible. Based on these findings, this cellulose-based injectable, thermo-responsive drug-loaded hydrogel is suitable for intelligent drug delivery systems.

Tough and strong sustainable thermoplastic elastomers nanocomposite with self-assembly of SI-ATRP modified cellulose nanofibers

The ingenious design of sustainable thermoplastic elastomers (STPEs) is of great significance for the goal of the sustainable development. However, the preparation of STPEs with good mechanical performance is still complicated and challenging. Herein, to achieve a simple preparation of STPEs with strong mechanical properties, two biobased monomers (tetrahydrofurfuryl methacrylate (THFMA) and lauryl methacrylate (LMA)) were copolymerized into poly (THFMA-co-LMA) (PTL) and grafted onto TEMPO oxidized cellulose nanofiber (TOCN) via one-pot surface-initiated atom transfer radical polymerization (SI ATRP). The grafting modified TOCN could be self-assembled into nano-enhanced phases in STPEs, which are conducive to the double enhancement of the strength and toughness of the STPEs, and the size of nano-enhanced phases is mainly affected by TOCN fiber length and molecular weight of grafting chains. Especially, with the addition of 7 wt% TOCN, tensile strength, tensile strain, toughness, and glass transition temperature (Tg) of TOCN based STPEs (TOCN@PTL) exhibited 140 %, 36 %, 215 %, and 6.8 °C increase respectively, which confirmed the leading level in the field of bio-based elastomers. In general, this work constitutes a proof for the chemical modification and self-assembly behavior of TOCN by one-pot SI ATRP, and provides an alternative strategy for the preparation of high-performance STPEs.

Antifouling and Water Flux Enhancement in Polyethersulfone Ultrafiltration Membranes by Incorporating Water-Soluble Cationic Polymer of Poly [2-(Dimethyl amino) ethyl Methacrylate]

Novel ultrafiltration (UF) polymer membranes were prepared to enhance the antifouling features and filtration performance. Several ultrafiltration polymer membranes were prepared by incorporating different concentrations of water-soluble cationic poly [2-(dimethyl amino) ethyl methacrylate] (PDMAEMA) into a homogenous casting solution of polyethersulfone (PES). After adding PDMAEMA, the effects on morphology, hydrophilicity, thermal stability, mechanical strength, antifouling characteristics, and filtration performance of these altered blended membranes were investigated. It was observed that increasing the quantity of PDMAEMA in PES membranes in turn enhanced surface energy, hydrophilicity, and porosity of the membranes. These new modified PES membranes, after the addition of PDMAEMA, showed better filtration performance by having increased water flux and a higher flux recovery ratio (FRR%) when compared with neat PES membranes. For the PES/PDMAEMA membrane, pure water flux with 3.0 wt.% PDMAEMA and 0.2 MPa pressure was observed as (330.39 L·m^-2·h^-1), which is much higher than that of the neat PES membrane with the value of (163.158 L·m^-2·h^-1) under the same conditions. Furthermore, the inclusion of PDMAEMA enhanced the antifouling capabilities of PES membranes. The total fouling ratio (TFR) of the fabricated PES/PDMAEMA membranes with 3.0 wt.% PDMAEMA at 0.2 MPa applied pressure was 36 percent, compared to 64.9 percent for PES membranes.

Cellulose-based functional hydrogels derived from bamboo for product design

Hydrogels have outstanding research and application prospects in the field of product design. Among them, the design and preparation of cellulose-based functional hydrogels derived from bamboo have attracted increasing research interest. Cellulose-based hydrogels not only have the skeleton function of hydrogels, but also retain excellent specificity, smart structural design, precise molecular recognition ability, and superior biocompatibility. Cellulose-based hydrogels show important application prospects in various fields, such as environmental protection, biomedicine, and energy. What's more, they are potentially viable for application in food packaging and plant agriculture, such as fertilizers release and crop production. Recently, researchers have extracted cellulose from bamboo and generated a variety of cellulose-based functional hydrogels with excellent properties by various cross-linking methods. In addition, a variety of multifunctional hybrid cellulose-based hydrogels have been constructed by introducing functional components or combining them with other functional materials, thus expanding the breadth and depth of their applications. Herein, we elaborate on advances in the field of cellulose-based hydrogels and highlight their applications in food packaging and plant agriculture. Meanwhile, the existing problems and prospects are summarized. The review provides a reference for the further development of cellulose-based hydrogels.

Progress on chemical modification of cellulose in “green” solvents

Chemical modification of cellulose in "green" solvents.

Amino acid-derived ABCBA-type antifouling biohybrid with multi-stimuli responsivity and contaminant removal capability

A multi-stimuli (pH/thermo/redox)-responsive amphiphilic poly(cysteine methacrylamide)-block-poly(N,N-dimethylaminoethyl methacrylate)-block-polybutadiene-block-poly(N,N-dimethylaminoethyl methacrylate)-block-poly(cysteine methacrylamide) (PCysMAM-b-PDMAEMA-b-PB-b-PDMAEMA-b-PCysMAM) pentablock copolymer biohybrids, based on hydrophobic PB, ampholytic redox responsive PCysMAM and dual (pH and temperature) stimuli responsive PDMAEMA segments,...

One-pot synthesis of 2-bromopropionyl esterified cellulose nanofibrils as hydrophobic coating and film

Bromo-esterified cellulose nanofibrils have been one-pot synthesized by direct heterogeneous 2-bromopropionyl esterification and in situ ultra-sonication to serve as versatile hydrophobic nm thick coating or 100 μm thick film.

Cellulose-based thermo-enhanced fluorescence micelles

Recently, cellulose-based stimuli-responsive nanomaterials have received significant attention because of its natural source and biocompatibility. In this study, cellulose-graft-poly(nisopropylacrylamide)-co-2-methyl-acrylic acid 2-carbazol-9-yl-ethyl ester (cellulose-g-(PNIPAAm&PCz)) block polymers were successfully synthesized by homogeneous atom transfer radical polymerization (ATRP) in LiCl/N,N-dimethylacetamide (DMAc) dissolution system. The block polymers showed different properties due to the different PCz content. The block polymer with low PCz content (cellulose-g-(PNIPAAm&PCz)1) was dispersed in water at 25 °C and self-assembled into micelles at 37 °C. On the other hand, the block polymer with high PCz content (cellulose-g-(PNIPAAm&PCz)2) was dissolved in DMF, THF, DMSO firstly, and dialyzed at 25 °C, 37 °C and 60 °C respectively to obtain the micelles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) indicated that the distribution range of micelles formed by cellulose-g-(PNIPAAm&PCz)1 was narrower than cellulose-g-(PNIPAAm&PCz)2. And the sizes of the micelles formed by cellulose-g-(PNIPAAm&PCz)2 had little difference under different solvents, but became bigger with the temperature increased. The micelles displayed thermo-enhanced fluorescence due to the thermal-driven chain dehydration of the grafted PNIPAAm brushes, which is contrary to the decrease of the fluorescence of the monomer when the temperature increased. The results provided a potential for the application of cellulose-based stimuli-responsive micelles in the field of drug delivery and fluorescent probes.

Nucleophilic Displacement Reaction on Tosyl Cellulose by L-Methionine to the Synthesis of Novel Water-Soluble Cellulose Derivative and Its Antibacterial Activity

A novel ampholytic cellulose derivative, cellulose-L-methionine, has been synthesized by means of an esterification reaction of microcrystalline cellulose with tosyl chloride (p-TsCl) in DMAc/LiCl (8%) at 8°C that was followed by nucleophilic displacement (SN) of the tosyl group by the L-methionine amino acid. The resulting structure of cellulose-L-methionine has been characterized by elemental analysis (CHNSO), Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and scanning electron microscopy (SEM). The antibacterial activity of the synthesized product was screened against Gram-positive and Gram-negative microbial strains such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, by the agar well diffusion method, and compared with commercial antibiotics such as ampicillin and chloramphenicol. It was found that antibacterial experiment revealed excellent antibacterial activity of the cellulose-methionine with respect to a minimal inhibitory concentration (MIC) reference.

Facile access to functional polyacrylates with dual stimuli response and tunable surface hydrophobicity

Well-defined functional polyacrylates with dual stimuli response and tunable surface hydrophobicity were synthesized via the recyclable Ni–Co alloy catalyzed reversible deactivation radical polymerization technique at ambient temperature.

Complementary multiple hydrogen-bond-based magnetic composite microspheres for high coverage and efficient phosphopeptide enrichment in bio-samples

Due to the number of phosphorylation sites, mono- and multiple-phosphopeptides exhibit significantly different biological effects. Therefore, comprehensive profiles of mono- and multiple-phosphopeptides are vital for the analysis of these biological and pathological processes. However, the most commonly used affinity materials based on metal oxide affinity chromatography (MOAC) show stronger selectivity toward mono-phosphopeptides, thus losing most information on multiple-phosphopeptides. Herein, we report polymer functionalized magnetic nanocomposite microspheres as an ideal platform to efficiently enrich both mono- and multiple-phosphopeptides from complex biological samples. Driven by complementary multiple hydrogen bonding interactions, the composite microspheres exhibited remarkable performance for phosphopeptide enrichment from model proteins and real bio-samples. Excellent selectivity (the molar ratio of nonphosphopeptides/phosphopeptides was 5000 : 1), high enrichment sensitivity (2 fmol) and coverage, as well as high capture rates of multiple-phosphopeptides revealed their great potential in comprehensive phosphoproteomics studies. More importantly, we successfully captured the cancer related phosphopeptides (from the phosphoprotein Stathmin-1) and identified their relevant phosphorylation sites from oral carcinoma patients' saliva and tissue lysate, demonstrating the potential of this material for phosphorylated disease marker detection and discovery.

Stimuli-responsive self-assembly of cellulose nanocrystals (CNCs): Structures, functions, and biomedical applications

Cellulose nanocrystals (CNCs) have received a significant amount of attention from the researchers. It is used as a nanomaterial for various applications due to its excellent physiochemical properties for the last few decades. Self-assembly is a phenomenon where autonomous reorganization of randomly oriented species occurs elegantly. Self-assembly is responsible for the formation of the hierarchical cholesteric structure of CNCs. This process is highly influenced by several factors, such as the surface chemistry of the nanoparticles, intermolecular forces, and the fundamental laws of thermodynamics. Various conventional experimental designs and molecular dynamics (MD) studies have been applied to determine the possible mechanism of self-assembly in CNCs. Different external factors, like pH, temperature, magnetic/electric fields, vacuum, also influence the self-assembly process in CNCs. Notably, better responses have been observed in CNCs-grafted polymer nanocomposites. These functionalized CNCs with stimuli-responsive self-assembly have immense practical applications in modern biotechnology and medicine. Herein, we have concisely discussed the mechanism of the self-assembled CNCs in the presence of different external factors such as pH, temperature, electric/magnetic fields, and their biomedical applications.

Enhanced Thermal-to-Flexible Phase Change Materials Based on Cellulose/Modified Graphene Composites for Thermal Management of Solar Energy

The applications of phase change materials (PCMs) in some practical circumstances are currently limited due to the constant strong rigidity, poor thermal conductivity, and low photoabsorption property. Therefore, the design of flexibility-enhanced, highly efficient PCMs is greatly desirable and challenging. In this work, novel PCM composites (CPmG-x) with stable forms and thermally induced flexibility were successfully prepared by grafting the comblike poly(hexadecyl acrylate) polymer (PA16, phase change working substance) onto a cellulose support by atom transfer radical polymerization (ATRP). Modified graphene (GN16) was incorporated into the synthesized material to enhance its enthalpy, thermal conductivity, and physical strength. The prepared CPmG-x composites exhibit excellent softness and flexibility after phase transition of PA16. The addition of GN16 increases the thermal conductivity and enthalpy of CPmG-x materials to 1.32 W m^-1 K^-1 (9 wt % GN16) and 103 J g^-1 (5 wt % GN16), respectively. Assessments of the solar-to-thermal energy conversion and storage efficiencies indicate that CPmG-x composites possess great potential for use in thermal energy management applications and solar energy collection systems.

The synthesis of bottlebrush cellulose-graft-diblock copolymer elastomers via atom transfer radical polymerization utilizing a halide exchange technique

A novel kind of bottlebrush cellulose-graft-diblock copolymer thermoplastic elastomer (Cell-g-PBA-b-PMMA) was synthesized by grafting from cellulose backbones via surface-initiated atom transfer radical polymerization (ATRP). The mechanical properties of the bottlebrush copolymer elastomers can be adjusted by controlling the block lengths and composition of the side chains.

CO2-Responsive Cellulose Nanofibers Aerogels for Switchable Oil-Water Separation

Cellulose nanofibers (CNFs) aerogels with controllable surface wettability were prepared by grafting poly( N, N-dimethylamino-2-ethyl methacrylate) (PDMAEMA) polymer brushes via surface-initiated atom-transfer radical polymerization. After grafting PDMAEMA polymer, the surface of the aerogel was hydrophobic. However, in the presence of CO₂, the surface of the aerogel gradually changes from hydrophobic to hydrophilic. The porous structure and CO₂-responsiveness of PDMAEMA brushes within the CNFs aerogels allowed for the on-off switching of the oil-water mixture separation process. These CNFs aerogels were recyclable and displayed attractive separation efficiency for oil-water mixture and surfactant-stabilized emulsions. Furthermore, the switchable surface wettability holds an advantage of avoiding oil-fouling, which will greatly improve its recyclability.

Preparation of hydrophobically modified cotton filter fabric with high hydrophobic stability using ARGET-ATRP mechanism

This paper reports on the hydrophobic modification of cotton fabric grafted with 1-octadecene via an activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP) mechanism. Particularly, the activation treatment of raw cotton fabric, its influence on the graft-copolymerization by the ARGET-ATRP method, along with the super-hydrophobicity and hydrophobic stability of the modified cotton fabric are discussed. Furthermore, the microstructure and elemental variation were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and the energy dispersion spectrum (EDS) technique. The results show that chemical activation of the raw cotton fabric can significantly improve the follow-up hydrophobic modification process. Specifically, the contact angle of the hydrophobically modified cotton fabric increased to 145° after activation, and thus, this fabric presents more stable hydrophobicity (corresponding to a 5.5% contact angle attenuation) than a non-activated fabric. The hydrophobic modification reaction was carried out using a chemically optimum stoichiometric ratio of m(CuBr₂) : m(C₉H₂₃N₃) : m(C₂H₅OH) : m(C₁₈H₃₆) : m(C₆H₈O₆) = 0.015 : 0.052 : 17.9 : 2.4 : 0.05, at a temperature of 30–55 °C over 8 h. Furthermore, the SEM and AFM images revealed that more copolymer micro/nano-level particles were present on the surface of the fibers of the hydrophobically modified cotton fabric, indicating that the hydrophobic property and stability of the cotton fabric increase with the grafting density on the cotton fabric.

This paper reports on the hydrophobic modification of cotton fabric grafted with 1-octadecene via an electron transfer (ARGET) atom transfer radical polymerization (ATRP) mechanism.

Dual Light- and pH-Responsive Composite of Polyazo-Derivative Grafted Cellulose Nanocrystals

As a type of functional group, azo-derivatives are commonly used to synthesize responsive materials. Cellulose nanocrystals (CNCs), prepared by acid hydrolysis of cotton, were dewatered and reacted with 2-bromoisobuturyl bromide to form a macro-initiator, which grafted 6-[4-(4-methoxyphenyl-azo) phenoxy] hexyl methacrylate (MMAZO) via atom transfer radical polymerization. The successful grafting was supported by Fourier transform infrared spectroscopy (FT-IR) and Solid magnetic resonance carbon spectrum (MAS 13C-NMR). The morphology and surface composition of the poly{6-[4-(4-methoxyphenylazo) phenoxy] hexyl methacrylate} (PMMAZO)-grafted CNCs were confirmed with Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The grafting rate on the macro-initiator of CNCs was over 870%, and the polydispersities of branched polymers were narrow. The crystal structure of CNCs did not change after grafting, as determined by X-ray diffraction (XRD). The polymer PMMAZO improved the thermal stability of cellulose nanocrystals, as shown by thermogravimetry analysis (TGA). Then the PMMAZO-grafted CNCs were mixed with polyurethane and casted to form a composite film. The film showed a significant light and pH response, which may be suitable for visual acid-alkali measurement and reversible optical storage.

Surface-initiated atom transfer radical polymerization grafting from nanoporous cellulose gels to create hydrophobic nanocomposites

Here, we present the preparation of hydrophobic nanoporous cellulose gel-g-poly(glycidyl methacrylate) (NCG-g-PGMA) nanocomposites by surface-initiated atom transfer radical polymerization (SI-ATRP) of glycidyl methacrylate (GMA) monomers and hydrophobic modification with pentadecafluorooctanoyl chloride (C7F15COCl) on the cellulose nanofibrils of the NCG. The successful grafting of PGMA and hydrophobic modification of C7F15CO- groups on the NCG was evaluated by Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed that the SI-ATRP and hydrophobic modification did not change the microscopic morphology and structure of the NCG-g-PGMA nanocomposites. Dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) showed remarkable thermomechanical properties and moderate thermal stability. The method has tremendous promise to use NCG as a platform for SI-ATRP and produce new functional NCG-based nanomaterials.