Effects of Surface Structure and Morphology of Nanoclays on the Properties of Jatropha Curcas Oil-Based Waterborne Polyurethane/Clay Nanocomposites

Bio-polyols based waterborne polyurethane coatings reinforced with chitosan-modified ZnO nanoparticles

The development of environmentally friendly waterborne polyurethane (WPU) coatings from bio-based polyols has received much attention due to increasing environmental concern and the depletion of petroleum resources. In this study, the WPU coatings derived from castor oil and soy polyol were modified by chain extender [bis(2-hydroxyethyl)amino]-methyl-phosphonic acid dimethyl ester. The effect of chitosan-modified ZnO (CS-ZnO) nanoparticles content on the properties of WPU/CS-ZnO coatings and their films were systematically investigated. The results indicated that WPU/CS-ZnO coatings displayed excellent storage stability and the particle sizes firstly decreased and then increased with CS-ZnO loading. CS-ZnO could improve tensile strength and Young's modulus but reduce the optical transparency of WPU/CS-ZnO films. CS-ZnO has a prominent reinforcement effect on the WPU/CS-ZnO matrix. With the addition of 2 wt% CS-ZnO, the tensile strength and Young's modulus of the WPU/CS-ZnO2 film reached 13.4 and 112.1 MPa, 1.68 and 2.6 times over neat WPU film, respectively. TGA results showed that the thermal stability of WPU/CS-ZnO films improved with increased CS-ZnO content. Furthermore, the WPU/CS-ZnO films' wettability decreased with the introduction of CS-ZnO. This work provides a simple and efficient strategy for preparing environmentally friendly bio-based WPU coatings, which are promising for application in the surface coating industry.

AFM Characterization of Halloysite Clay Nanocomposites' Superficial Properties: Current State-of-the-Art and Perspectives

Natural halloysite clay nanotubes (HNTs) are versatile inorganic reinforcing materials for creating hybrid composites. Upon doping HNTs with polymers, coating, or loading them with bioactive molecules, the production of novel nanocomposites is possible, having specific features for several applications. To investigate HNTs composites nanostructures, AFM is a very powerful tool since it allows for performing nano-topographic and morpho-mechanical measurements in any environment (air or liquid) without treatment of samples, like electron microscopes require. In this review, we aimed to provide an overview of recent AFM investigations of HNTs and HNT nanocomposites for unveiling hidden characteristics inside them envisaging future perspectives for AFM as a smart device in nanomaterials characterization.

Durable and transparent super anti-wetting coatings with excellent liquid repellency and anti-fouling performance based on fluorinated polysiloxane

Super anti-fouling coatings are of great interest because of their good liquid repellency and anti-fouling performance. However, it is challenging to prepare durable and transparent super anti-fouling coatings, especially via...

Nanocelluloses Reinforced Bio-Waterborne Polyurethane

The aim of this work was to evaluate the influence of two kinds of bio- nano-reinforcements, cellulose nanocrystals (CNCs) and bacterial cellulose (BC), on the properties of castor oil-based waterborne polyurethane (WBPU) films. CNCs were obtained by the acidolysis of microcrystalline cellulose, while BC was produced from Komagataeibacter medellinensis. A WBPU/BC composite was prepared by the impregnation of a wet BC membrane and further drying, while the WBPU/CNC composite was obtained by casting. The nanoreinforcement was adequately dispersed in the polymer using any of the preparation methods, obtaining optically transparent compounds. Thermal gravimetric analysis, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, dynamical mechanical analysis, differential scanning calorimetry, contact angle, and water absorption tests were carried out to analyze the chemical, physical, and thermal properties, as well as the morphology of nanocelluloses and composites. The incorporation of nanoreinforcements into the formulation increased the storage modulus above the glass transition temperature of the polymer. The thermal stability of the BC-reinforced composites was slightly higher than that of the CNC composites. In addition, BC allowed maintaining the structural integrity of the composites films, when they were immersed in water. The results were related to the relatively high thermal stability and the particular three-dimensional interconnected reticular morphology of BC.

Novel Copper Nanoparticles Intercalated Polyurethane Heparin/Poly-L-Lysine Chelates Coated Stents: Viability Study for Coronary Vascular Cells and Aneurysms Treatments

Continuous delayed endothelium regeneration and continues thrombosis development designate a task for coronary artery stent rehabilitation. To progress the direct vascular cell behavior, aneurysms treatments and compatibility of cardiovascular implants novel copper intercalated polyurethane heparin/poly-L-lysine chelates treated stent has established in this report. The functional group modifications, structural characteristics, and stability of the chelates have investigated for polyurethane heparin: poly-L-lysine, copper intercalated polyurethane heparin/poly-L-lysine coated stents. The FTIR results showed the copper intercalation at 446 cmr and the Cu 2s peak at 932 eV from XPS also indicated that the successful coating of copper, polyurethane heparin, poly-L-lysine. The relative surface geomorphology of the chelates displayed the uniform Cu coating consisting of multilayer poly-L-lysine on the substrate. The stability and biocompatibility studies indicated the significantly enhanced performance with clot the APTT and TT periods as clotting and cell proliferation assessments. This type of composite proposes a stage on a stent external area for discerning track of vascular cell performance and aneurysms treatments with low side effects.

Environmentally friendly, durable and transparent anti-fouling coatings applicable onto various substrates

Anti-fouling coatings are of great interest because of their unique wettability and self-cleaning property, but their widespread applications are seriously hindered by low stability, heavy usage of fluorinated compounds and low transparency, etc. Here, we report a new kind of smooth anti-fouling coatings based on methyltrimethoxysilane. The coatings were fabricated by preparing a stock solution via hydrolytic condensation of methyltrimethoxysilane in isopropanol, followed by wiping the glass slide with the non-woven fabric that sucked the stock solution. The transparent anti-fouling coatings have excellent anti-fouling properties against various fluids such as water, n-hexadecane, diiodomethane, daily encountered liquids (e.g., milk, coffee, red wine, soy sauce and cooking oil), mark seals, artificial fingerprint liquids and paints (both water-based and oil-based), etc. The fluids can easily roll off from the 4-30° titled coatings. Furthermore, the coatings have good mechanical (200 cycles of friction, scratching and bending), chemical (saline, acidic and basic solutions) and thermal stability (boiling and 300 °C heating) regarding the easy sliding behavior of the probing liquids. In addition, the anti-fouling coatings are applicable onto various substrates via the same procedure. The smooth anti-fouling coatings have huge potential applications, owing to the excellent anti-fouling properties, high stability as well as the non-fluorinated and simple preparation method.

Enhancing the mechanical and thermal properties of waterborne polyurethane composites with thermoset epoxy resin microspheres

A facile way to prepare WPU with good mechanical and thermal properties by adding epoxy microspheres.

Core-Shell Nanohybrid Elastomer Based on Co-Deposition Strategy to Improve Performance of Soy Protein Adhesive

Exploitation of a versatile strategy for fabricating a plant protein adhesive with outstanding adhesion and water resistance is a growing concern in the ecofriendly wood industry. Herein, a core-shell nanohybrid elastomer composed of the cellulose nanocrystal (CNC) core and elastic polyurethane shell is prepared via a co-deposition strategy and then used as an efficient reinforcer to improve the performances of soy protein (SP) adhesive. It is found that the core-shell nanohybrid acts as a multiple cross-linker, giving rise to the construction of a stable protein adhesive system. Moreover, owing to the nanohybrid design combining "strong yet tough" qualities, the hard CNC serves to repair the discontinuous protein adhesion layer for a rigid and integrated system, while the elastic polyurethane contributes to energy dissipation, thus endowing the protein adhesive with excellent overall cohesive strength. Given such synergistic effects, the modified SP-based adhesive exhibits a significant improvement in both adhesion and water resistance, particularly achieving a 311.8% increase in wet adhesion strength compared to that of the pristine SP adhesive. This work may provide an effective guide for the preparation and practical application of high-performance plant-protein-based adhesive.

Role of the Oxethyl Unit in the Structure of Vegetable Oil-Based Plasticizer for PVC: An Efficient Strategy to Enhance Compatibility and Plasticization

Developing vegetable oil-derived primary plasticizers for poly(vinyl chloride) (PVC) is still a challenge because of their insufficient compatibility. As described in this work, we report the synthesis of plasticizers through the esterification of polyethylene glycol methyl ether and dimer acid, in which dimer acid is renewable material prepared via a two-step reaction (1) the hydrolysis of fatty acids from soybean oil at 70 °C and (2) subsequent Diels-Alder reaction at 250 °C. The resulting plasticizers, dimer acid-derived polyethylene glycol methyl ether esters (DA-2n, 2n = 2, 4, 6 or 8 referring to the number of oxethyl units per molecule), were blended with PVC. It was found that the tensile properties, transparency, and thermal stability of plasticized PVC (PVC-DA-2n) increased significantly with an increase in the number of oxyethyl units. Fourier-transform infrared spectroscopy analysis revealed that its good compatibility can be attributed to the strong interaction between oxyethyl units and PVC. As the number of the oxyethyl units of plasticizer increased, the glass transition temperature (T_g) of the corresponding plasticized PVC samples decreased from 62.3 (PVC-DA-2) to 35.4 °C (PVC-DA-8). Owing to the excellent plasticization of DA-8, the performances of PVC-DA-8 were comparable or better than that of the PVC plasticized using commercial dioctyl terephthalate (DOTP). The simple but efficient method of this study provides a new avenue for the preparation of vegetable oil-based plasticizers for PVC.

Reinforcement of Castor Oil-Based Polyurethane with Surface Modification of Attapulgite

Polyurethane/attapulgite (PU/ATT) nanocomposites derived from castor oil were prepared by incorporation of 8 wt % ATT, acid-treated ATT, and KH560-treated ATT. The effects of three ATTs (ATT, acid-ATT, and KH560-ATT) on the comprehensive properties of PU/ATT nanocomposites were systematically investigated. The results showed that the incorporation of 8 wt % of three ATTs could produce an obvious reinforcement on the castor oil-based PU and that the silane modification treatment, rather than the acid treatment, has the more effective reinforcement effect. SEM images revealed the uniform dispersion of ATT in the PU matrix. DMA confirmed that the storage modulus and glass transition temperature (Tg) of PU/ATT nanocomposites were significantly increased after blending with different ATTs. For PU/KH560-ATT8 nanocomposites, the thermal stability of the PU was obviously enhanced by the addition of KH560-ATT. In particular, 8 wt % KH560-ATT loaded castor oil-based PU nanocomposites exhibit an obvious improvement in tensile strength (255%), Young's modulus (200%), Tg (5.1 °C), the storage modulus at 25 °C (104%), and the initial decomposition temperature (7.7 °C). The prepared bio-based PU materials could be a potential candidate to replace petroleum-based PU products in practical applications.

Dopamine-Mediated Pre-Crosslinked Cellulose/Polyurethane Block Elastomer for the Preparation of Robust Biocomposites

The development of micro- and nanofibril cellulose to improve strength while reducing the side effects of toughness and water resistance can benefit integrated polymer performance. Inspired by the interior microstructure of mussel byssus, this paper proposed an efficient means of generating an active block microfibrillated cellulose/polyurethane elastomer using an epoxy monomer as a pre-crosslinked agent with the addition of a poly(dopamine) layer. The block elastomer served as a multifunctional crosslinker, constructing a covalent network and interfacial hydrogen bonding that interlinked the elastomer with a soy protein isolate (SPI) matrix. Compared with the pristine SPI film, the introduction of the block elastomer induced remarkable improvements in tensile strength and toughness (146.7 and 102.1%, respectively). Additionally, the block elastomer was employed to further estimate its reinforcing effect in SPI resin modification, which also exhibited favorable water resistance and adhesion performance. This strategy may provide a new approach for constructing superior elastomers to reinforce applicable biomass composites.

Synthesis, Characterization and the Solvent Effects on Interfacial Phenomena of Jatropha Curcas Oil Based Non-Isocyanate Polyurethane

Non-isocyanate polyurethane (NIPU) was prepared from Jatropha curcas oil (JCO) and its alkyd resin via curing with different diamines. The isocyanate-free approach is a green chemistry route, wherein carbon dioxide conversion plays a major role in NIPU preparation. Catalytic carbon dioxide fixation can be achieved through carbonation of epoxidized derivatives of JCO. In this study, 1,3-diaminopropane (DM) and isophorone diamine (IPDA) were used as curing agents separately. Cyclic carbonate conversion was catalyzed by tetrabutylammonium bromide. After epoxy conversion, carbonated JCO (CJCO) and carbonated alkyd resin (CC-AR) with carbonate contents of 24.9 and 20.2 wt %, respectively, were obtained. The molecular weight of CJCO and CC-AR were determined by gel permeation chromatography. JCO carbonates were cured with different amine contents. CJCO was blended with different weight ratios of CC-AR to improve its characteristics. The cured NIPU film was characterized by spectroscopic techniques, differential scanning calorimetry, and a universal testing machine. Field emission scanning electron microscopy was used to analyze the morphology of the NIPU film before and after solvent treatment. The solvent effects on the NIPU film interfacial surface were investigated with water, 30% ethanol, methyl ethyl ketone, 10% HCl, 10% NaCl, and 5% NaOH. NIPU based on CCJO and CC-AR (ratio of 1:3) with IPDA crosslink exhibits high glass transition temperature (44 °C), better solvent and chemical resistance, and Young's modulus (680 MPa) compared with the blend crosslinked with DM. Thus, this study showed that the presence of CC-AR in CJCO-based NIPU can improve the thermomechanical and chemical resistance performance of the NIPU film via a green technology approach.