Polyurethane Copolymers Research Articles

Synthesis of Water-Soluble Polyurethane Using Lignin, Dopamine and Zn2+ and Its Effects on Paper Properties

A novel water-soluble polyurethane copolymer (i.e., LnBPU-[Zn(DOPA)2]) was synthesized through a route mainly using a prepolymer (i.e., BPU), lignin, dopamine and Zn2+ as the raw materials by cross-linking copolymerization. The optimal reaction conditions are as follows: m(Lignin):m(BPU) is 1:4, time is 4 h and temperature is 70 °C. The prepared LnBPU-[Zn(DOPA)2] was turned out to improve the strength, resistance to water, oil and Escherichia coli of fibre when it was evenly coated on the paper with a dose of 15 g/m2. SEM & EDS, FT-IR, GPC confirmed that the crosslinking copolymerization was enhanced by dopamine and Zn2+, which can give the polyurethane copolymer better strength and water and oil resistance. This study provided an efficient and green approach for preparing lignin-based polyurethane, and contributes to the application of paper in more fields such as food or medical packaging.

One-pot synthesis of copolymers through the application of the thermally reversible furan/maleimide Diels–Alder reaction. 2. preparation of polyester–polyurethane copolymers

One-pot synthesis of copolymers through the application of the thermally reversible furan/maleimide Diels–Alder reaction. 2. preparation of polyester–polyurethane copolymers

Electrical aligned polyurethane nerve guidance conduit modulates macrophage polarization and facilitates immunoregulatory peripheral nerve regeneration

Biomaterials can modulate the local immune microenvironments to promote peripheral nerve regeneration. Inspired by the spatial orderly distribution and endogenous electric field of nerve fibers, we aimed to investigate the synergistic effects of electrical and topological cues on immune microenvironments of peripheral nerve regeneration. Nerve guidance conduits (NGCs) with aligned electrospun nanofibers were fabricated using a polyurethane copolymer containing a conductive aniline trimer and degradable L-lysine (PUAT). In vitro experiments showed that the aligned PUAT (A-PUAT) membranes promoted the recruitment of macrophages and induced their polarization towards the pro-healing M2 phenotype, which subsequently facilitated the migration and myelination of Schwann cells. Furthermore, NGCs fabricated from A-PUAT increased the proportion of pro-healing macrophages and improved peripheral nerve regeneration in a rat model of sciatic nerve injury. In conclusion, this study demonstrated the potential application of NGCs in peripheral nerve regeneration from an immunomodulatory perspective and revealed A-PUAT as a clinically-actionable strategy for peripheral nerve injury.

Super-Flexible Water-Proof Actuators.

Humidity-responsive materials hold broad application prospects in sensing, energy production, and other fields. Particularly, humidity-sensitive, flexibility, and water resistance are pivotal factors in the development of optimized humidity-responsive materials. In this study, hydrophobic linear polyurethane and hydrophilic 4-vinylphenylboronic acid (4-VPBA) form a semi-intercross cross-linking network. This copolymer of polyurethane exhibits excellent humidity-sensitive, mechanical properties, and water resistance. Its maximum tensile strength and maximum elongation can reach 40.56MPa and 543.47%, respectively. After being immersed in water at various temperatures for 15 days, it exhibited a swelling ratio of only 3.28% in water at 5°C and 9.58% in water at 70°C. While the presence of 4-VPBA network imparts humidity-sensitive, reversible, and multidirectional bending abilities, under the stimulus of water vapor, it can bend 43° within 1.4s. The demonstrated material surpasses current bidirectional humidity actuators in actuating ability. Based on these characteristics, automatically opening waterproof umbrellas and windows, as well as bionic-arms, crawling robots, and self-propelled boats, are successfully developed.

Multifunctional Anti-Icing Gel Surface with Enhanced Durability.

Materials with low ice adhesion and long-lasting anti-icing properties remain an ongoing challenge in ultralow temperature environments (≤-30 °C). This study presents a gel material consisting of a polymer matrix (copolymer of polyurethane and acrylamide) and an anti-icing agent, ethylene glycol (EG), designed for anti-icing applications at ultralow temperatures. The surface shows a prolonged droplet freezing delay of ca. 322 s at -30 °C and frost resistance properties. It also exhibits an ice adhesion strength of 1.1 kPa at -10 °C and 39.8 kPa at -50 °C, resulting from the interaction between EG and water molecules that hinders the crystallization of ice as well as the significant mismatch between elastic gel and ice. In addition, the gel surface exhibits favorable anti-icing durability, with an ice adhesion strength below 20.0 kPa after 25 icing/deicing cycles and mechanical scratch tests. The gel demonstrates remarkable thermal durability, achieved through the H-bonds between the EG and polymer matrix. The H-bonds further enhance the anti-icing performance, thereby remarkably decreasing EG depletion and improving anti-icing durability. Overall, these properties suggest the potential application of this gel material in harsh environments including polar regions.

Theoretical modeling of predicting elastic modulus of polyurethane copolymer/organic-montmorillonite nanocomposite

A structure of theoretical models set was suggested to predict the elastic moduli of polyurethane copolymer (PUC)/organic modified montmorillonite (OMMT) nanocomposites (NCs) in terms of length (L) to thickness (t) ratio and volume fraction ([Formula: see text]) of OMMT nanoparticles. The predicted elastic modulus outcomes of PUC/OMMT NCs were compared with experiment data. The outcome demonstrated that the suggested aspect ratio of predicted elastic modulus decreased with increased [Formula: see text] of OMMT compared to experimental data. The largest value of effective aspect ratio belonged to the Hui–Shia model over all OMMT [Formula: see text]. The modified Halpin–Tsai model incorporated with the factor for decreasing modulus (FFDM) recorded the lowest range of percentage error between theoretical and experimental data around 0.385–0.816% at [Formula: see text] (4[Formula: see text]wt.%) OMMT.

Efficient Regulation of the Cross-Linking Structure in Polyurethane: Achieving Outstanding Processing and Mechanical Properties for a Wind Turbine Blade.

Although epoxy resin has been extensively used in the field of wind turbine blades, polyurethane has attracted much attention in recent years, due to its potential value of better fatigue resistance, lower processing viscosity and higher strength than epoxy resin blades. Herein, we construct a dense cross-linking structure in polyurethane (PU) based on different amounts of hydroxypropyl methacrylate (HPMA) with low processing viscosity and excellent mechanical properties. By increasing the content of HPMA, the thermal stability of PU is enhanced, but the micro-morphology does not change significantly. When the content of HPMA is 50 g (in 200 g copolymer), the PU sample PH-50 exhibits a viscosity of 70 MPa·s and a gelation time of 120 min at 25 °C, which is sufficient to complete processes like pouring and filling. By post-curing the PH-50 at 80 °C for 2 h, the heat distortion temperature can reach 72 °C, indicating the increase of temperature resistance. The PU copolymers also have excellent mechanical and dynamic thermo-mechanical properties due to the cross-linking structure between PU chains and poly-HPMA chains. Additionally, the PU copolymer has excellent compatibility with various glass fiber fabrics (GFF), showing a good match in the vacuum infusion experiment and great properties in the mechanical test. By compounding PH-50 with GFF, the composite with high strength is easily prepared for a wind turbine blade in various positions. The tensile strengths of the composites are all over 1000 MPa in the 0° direction. Such composites are promising for the future development of wind turbine blades that meet the stringent requirements for outstanding processing and mechanical properties.

Preparation of pH-responsive polyurethane nano micelles and their antibacterial application

Considering the differences in pH between bacterial infection microenvironment and normal tissues, a series of pH-responsive drug-release amphiphilic polyurethane copolymers (DPU-g-PEG) have been prepared in this work. Fourier transform infrared (FT-IR) spectroscopy and 1H NMR was selected to detect the structure of the condensed polymers. The DPU-g-PEG amphiphilic copolymers could form stable micelles with a hydrophilic shell of polyethylene glycol (PEG) and a hydrophobic core of polylactic acid (PLA). We loaded a model drug called triclosan onto DPU-g-PEG micelles and studied how pH affects their particle size, Zeta potential, and drug release performance. The results revealed that when exposed to acidic conditions, the surface potential of DPU-g-PEG micelles changed, the micelles’ particle size increased, and the drug release performance was significantly enhanced. These results suggested that the micelles prepared in this study can release more antibacterial substances at sites of bacterial infection. Meanwhile, we also investigated the impact of different ratios of soft and hard segments on the properties of micelles, and the results showed that the pH responsiveness of micelles was strongest when the ratio of soft segments (PLLA diol + PEG 2000): 1,6-hexamethylene diisocyanate (HDI): 2,6-Bis-(2-hydroxy-ethyl)-pyrrolo[3,4-f]isoindole-1,3,5,7-tetraone (DMA) = 1: 1.2: 0.2. Furthermore, the results of inhibition zone test, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) all confirmed the antibacterial activity of triclosan-load DPU-g-PEG micelles. In conclusion, the DPU-g-PEG micelles produced in this study have the potential to be used as intelligent drug delivery systems in the biomedical field.

Synthesis and Characterization of Cresol based Benzoxazine–Polyurethane Copolymer for Anti-corrosion Performance of Mild Steel

The cresol based polymeric materials were synthesized by using benzoxazine and polyurethanes as copolymer. Three copolymers were synthesized by varying the quantity of polyurethane content and studied their corrosion inhibition properties. The synthesized monomer, which has cresol as the center core was characterized by the NMR, FT-IR and UV-visible spectroscopic methods. All the obtained benzoxazine polymers were also analyzed by the FT-IR and UV-visible spectroscopy. In relation to corrosion inhibition studies, Tafel and impedance experiments were conducted, revealing that benzoxazine-polymer with a higher polyurethane content has improved anti-corrosive characteristics. Additionally, the physical properties of the materials were also studied such as water absorption and gel content studies. Furthermore, the density functional theory calculation was also carried out for the monomer, which explores the better results that are matched with the other experimental studies.

Partial crystalline organosilicon-based polysiloxane-polyurethane copolymers

Partial crystalline polysiloxane-based polyurethane copolymers were prepared by using hydroxyethoxypropyl capped polydimethylsiloxane (PDMS) as soft segment and α,ω-(bis (hydroxyethylthioether) ethyl)-disiloxane as chain extender. Due to this partial crystalline structure, the copolymer shows fairly good tensile properties and multiple shape deformation property. Repeated tensile tests revealed that stretch led to crystal destruction, and the microstructure of samples became stable after twice stretches. The lost crystallinity got 85.1% recovered upon treated at 60 °C for 1 h. It was proved that partial crystallization properties of the polysiloxane-polyurethane copolymer were from combined effects of polysiloxane soft segment and disiloxane chain extender. This unique crystallization kinetics of -(Si-O-Si)x- structure coexisting in soft and hard segments is regarded as one main reason to form crystalline hard segment domains in a common two-step synthesis.

The core-shell structured aqueous dispersions of the siloxane-grafted polyurethane copolymers with high transparency

We have synthesized the siloxane-grafted polyurethane copolymers aqueous dispersions by semi-continuous emulsion polymerization. The mono-methacryloxypropyl terminated polydimethylsiloxane was used to react with the acrylate-terminated waterborne polyurethane, which served as seed emulsions. It is obtained that the as-synthesized copolymer dispersions are stable and have small particle sizes ranging from 77 nm to 120 nm, and they possess core-shell structures. Moreover, the results show that the prepared films exhibit high transparency and hydrophobic surface. Moreover, the enrichment of siloxane and the heterogeneous structure on the film surface was studied. The results of Raman spectra disclose that the intensities of siloxane on the surface change over time during the film formation. These results are correlated to the pressure difference of droplets and low surface tension of siloxane segments. The as-synthesized dispersions promise to be applied in the displayer coatings.

Synergetic Effect of Electrical and Topographical Cues in Aniline Trimer-Based Polyurethane Fibrous Scaffolds on Tissue Regeneration.

Processibility and biodegradability of conductive polymers are major concerns when they are applied to tissue regeneration. This study synthesizes dissolvable and conductive aniline trimer-based polyurethane copolymers (DCPU) and processes them into scaffolds by using electrospinning with different patterns (random, oriented, and latticed). The effects of topographic cue changes on electrical signal transmission and further regulation of cell behaviors concerning bone tissue are researched. Results show that DCPU fibrous scaffolds possessed good hydrophilicity, swelling capacity, elasticity, and fast biodegradability in enzymatic liquid. In addition, the conductivity and efficiency of electrical signal transmission can be tuned by changing the surface's topological structure. Among them, oriented DCPU scaffolds (DCPU-O) showed the best conductivity with the lowest ionic resistance value. Furthermore, the viability and proliferation results of bone mesenchymal stem cells (BMSCs) demonstrate a significant increase on three DCPU scaffolds compared to AT-free scaffolds (DPU-R). Especially, DCPU-O scaffolds exhibit superior abilities to promote cell proliferation because of their unique surface topography and excellent electroactivity. Concurrently, the DCPU-O scaffolds can synergistically promote osteogenic differentiation in terms of osteogenic differentiation and gene expression levels when combined with electrical stimulation. Together, these results suggest a promising use of DCPU-O fibrous scaffolds in the application of tissue regeneration.

Green Biodegradable Polylactide-Based Polyurethane Triblock Copolymers Reinforced with Cellulose Nanowhiskers

A novel series of biodegradable polylactide-based triblock polyurethane (TBPU) copolymers covering a wide range of molecular weights and compositions were synthesized for potential use in biomedical applications. This new class of copolymers showed tailored mechanical properties, improved degradation rates, and enhanced cell attachment potential compared to polylactide homopolymer. Triblock copolymers, (TB) PL-PEG-PL, of different compositions were first synthesized from lactide and polyethylene glycol (PEG) via ring-opening polymerization in the presence of tin octoate as the catalyst. After which, polycaprolactone diol (PCL-diol) reacted with TB copolymers using 1,4-butane diisocyanate (BDI) as a nontoxic chain extender to form the final TBPUs. The final composition, molecular weight, thermal properties, hydrophilicity, and biodegradation rates of the obtained TB copolymers, and the corresponding TBPUs were characterized using 1H-NMR, GPC, FTIR, DSC, and SEM, and contact angle measurements. Results obtained from the lower molecular weight series of TBPUs demonstrated potential use in drug delivery and imaging contrast agents due to their high hydrophilicity and degradation rates. On the other hand, the higher molecular weight series of TBPUs exhibited improved hydrophilicity and degradation rates compared to PL-homopolymer. Moreover, they displayed improved tailored mechanical properties suitable for utilization as bone cement, or in regeneration medicinal applications of cartilage, trabecular, and cancellous bone implants. Furthermore, the polymer nanocomposites obtained by reinforcing the TBPU3 matrix with 7% (w/w) bacterial cellulose nanowhiskers (BCNW) displayed a ~16% increase in tensile strength, and 330% in % elongation compared with PL-homo polymer.

Development of a Slow-Degrading Polymerized Curcumin Coating for Intracortical Microelectrodes.

Intracortical microelectrodes are used with brain-computer interfaces to restore lost limb function following nervous system injury. While promising, recording ability of intracortical microelectrodes diminishes over time due, in part, to neuroinflammation. As curcumin has demonstrated neuroprotection through anti-inflammatory activity, we fabricated a 300 nm-thick intracortical microelectrode coating consisting of a polyurethane copolymer of curcumin and polyethylene glycol (PEG), denoted as poly(curcumin-PEG1000 carbamate) (PCPC). The uniform PCPC coating reduced silicon wafer hardness by two orders of magnitude and readily absorbed water within minutes, demonstrating that the coating is soft and hydrophilic in nature. Using an in vitro release model, curcumin eluted from the PCPC coating into the supernatant over 1 week; the majority of the coating was intact after an 8-week incubation in buffer, demonstrating potential for longer term curcumin release and softness. Assessing the efficacy of PCPC within a rat intracortical microelectrode model in vivo, there were no significant differences in tissue inflammation, scarring, neuron viability, and myelin damage between the uncoated and PCPC-coated probes. As the first study to implant nonfunctional probes with a polymerized curcumin coating, we have demonstrated the biocompatibility of a PCPC coating and presented a starting point in the design of poly(pro-curcumin) polymers as coating materials for intracortical electrodes.

Toward regulating biodegradation in stages of polyurethane copolymers with bicontinuous microphase separation.

For typical biodegradable polymers, their overall performance almost declines exponentially to the degradation degree, which inevitably leads to a dilemma between the requirements of service life and retention time in the environment (both in vitro and in vivo). It is a great challenge to develop a biodegradable polymeric device with relatively stable performance in service while rapidly degrading out of service. Herein, we demonstrate an effective strategy to control degradation of biodegradable polymers in stages by constructing separated bicontinuous microphases with very different microphase degradation rates. First, polyurethane copolymers (PCL-b-CrP-U) containing two blocks, i.e., semicrystalline poly(ε-caprolactone) (PCL) blocks and amorphous random copolymer blocks (CrP) based on ε-CL and p-dioxanone (PDO), were synthesized. The microscopic morphology of PCL-b-CrP-U is investigated by an alkali-accelerated degradation experiment, which also demonstrates that the chain cleavage-induced crystallization during degradation resulted in a self-reinforcement by forming degradation residues with a scaffold-like morphology. The tensile test shows that PCL-b-CrP-U has excellent mechanical properties (1500% of elongation at break, a tensile strength of about 7.5 MPa, and an elastic modulus of 40.0 MPa). The degradation experiments with artificial pancreatic juice as a working medium reveal that PCL-b-CrP-U samples containing relatively high PDO units exhibit a three-stage degradation, i.e. an induction stage, a steady degradation stage and an accelerated degradation stage. The CrP phase preferentially hydrolyzes to form some microchannels due to its amorphous nature and relatively high hydrophilicity, effectively accelerating the entry of water and enzymes into the inner parts of the sample. Meanwhile, at this stage, those originally amorphous PCL segments gradually crystalize owing to their enhanced chain mobility induced by the chain cleavage, forming a "scaffold"-like structure, which effectively reinforces the sample to resist the damage from external force and therefore guarantees a relatively stable mechanical performance of PCL-b-CrP-U during service. With the further depletion of the CrP phase, the intermediate "scaffold"-like structure is also very beneficial to accelerate the degradation of residues owing to its large specific surface area, which is expected to be beneficial for preventing long-term retention of the implantation devices.

Molecular design of a highly matched and bonded interface achieves enhanced thermal boundary conductance.

Interfacial binding and phonon mismatch are two crucial parameters in determining thermal boundary conductance. However, it is difficult for polymer/metal interfaces to possess both significant interfacial binding and weak phonon mismatch to achieve enhanced thermal boundary conductance. Herein, we circumvent this inherent trade-off by synthesizing a polyurethane and thioctic acid (PU-TA) copolymer with multiple hydrogen bonds and dynamic disulfide bonds. Using PU-TA/aluminum (Al) as a model interface, we demonstrate that the thermal boundary conductance of the PU-TA/Al interfaces measured by transient thermoreflectance is 2-5 times higher than that of traditional polymer/Al interfaces, which is attributed to the highly matched and bonded interface. Furthermore, a correlation analysis is developed, which demonstrates that interfacial binding has a greater impact than phonon mismatch on thermal boundary conductance at a highly matched interface. This work provides a systematic understanding of the relative contributions of the two dominant mechanisms to thermal boundary conductance by tailoring the polymer structure, which has applications in thermal management materials.

Self-healing polyurethane-polypropylene oxide copolymers for the protection of carbon and glass fiber-reinforced composites

Polyurethane-polypropylene oxide block copolymers containing fragments of an adduct capable of self-healing by the Diels-Alder reaction mechanism have been synthesized and studied for the first time. All obtained polyurethane copolymers were characterized by IR spectroscopy. The temperature transitions and thermal stability of copolymer melts were determined by using the methods of differential scanning calorimetry and thermogravimetric analysis. The self-healing effect was confirmed using a thermal cycling procedure on pre-damaged samples of modified polyurethanes and surface morphology studies. The perspective of the work begun on the creation of self-healing protective polyurethane coatings are shown.

Mechanical properties of hybrid fiber reinforced ternary-blended alkali-activated materials

This study employed fly ash, blast furnace slag and steel slag to synthesize ternary-blended alkali-activated materials (AAMs) in order to make full use of the industrial solid wastes and improve the mechanical performance by synergistic effects of the precursors. However, peudo-brittle nature is still the main problem of ternary-blended AAMs. To solve this problem, the effect of hybrid fibers consisting of high-modulus steel (ST) fiber and low-modulus Polyvinyl Alcohol (PVA) fiber on the mechanical properties of the ternary-blended AAMs was evaluated by testing their setting time, flowability, uniaxial compressive strength (UCS), indirect tensile strength (IDT), uniaxial tensile strength (UTS), and three-point bending strength (3PBS). Also, the microstructure of the matrix and fibers were analyzed using a scanning electron microscope. The results show that the flowability and setting time increased with the increasing replacement of PVA fiber by ST fiber. At the PVA/ST fiber volume ratio of 1:1, the AAMs cured for 28 days achieved the highest UCS, IDT, UTS, and 3PBS, which were 32 %, 91 %, 80 % and 114.7 % higher than the AAMs without fiber reinforcement, respectively. The fracture pattern and microstructure illustrated that the best synergistic effect of hybrid fibers was achieved at the PVA:ST fiber ratio of 1:1, at which the small-sized PVA fibers and large-sized ST fibers can inhibit the propagation of micro- and macro-cracks at early and late deformation processes. Furthermore, the ultimate elongation of the composite was improved from 2.62 % to 4.21 % and 5.3 % by modifying the PVA fiber with acrylic polyurethane copolymer and replacing the PVA fiber with polyethylene fiber, respectively, implying the significance of surface hydrophilicity of low-modulus fiber on the ductility of AAMs. This study provided a guide for synthesizing and tailoring the mix design of hybrid-fiber-reinforced ternary AAMs with better strength and ductility.

Carbon nanodots calibrated fluorescent probe of QD@amphiphilic polyurethane for ratiometric detection of Hg (II)

Because of its strong toxicity to the ecosystem and human beings, mercury is regarded as one of the most hazardous heavy metals. Among various fluorescent sensors that have been designed for Hg (II) detection, the probes showing Hg (II) concentration dependent ratiometric fluorescent responses normally exhibited improved analytical performance. Herein, we have synthesized series of amphiphilic polyurethane (PU) to encapsulate hydrophobic fluorescent quantum dots (QD) via the emulsion confinement self-assembly, leading to generation of QD@PU colloids whose red emission can be selectively quenched by Hg (II) among other metal ions. In order to further improve the Hg (II) detection performance of QD@PU probe, the green emitting carbon nanodots (CD) were synthesized and conjugated with QD@PU, resulting to formation of CD-QD@PU colloidal probe showing ratiometric fluorescent response towards Hg (II), which finally contributed to an enhanced sensitivity and wider linear range for Hg (II) detection. More interestingly, both QD@PU and CD-QD@PU doped stretchable PU membranes still hold naked eye discrimination for Hg (II). Basically, the current work revealed a universal protocol to prepare fluorescent probe for Hg (II) detection using PU and low dimensional fluorescent nanoparticles as building blocks, which will open new way for design and fabrication of other advanced sensors and analytical devices. • An amphiphilic block copolymer of polyurethane (PU) were synthesized. • PU was used to encapsulate fluorescent quantum dots (QD) to obtain QD@PU colloids. • The fluorescence of QD@PU colloids can be selectively quenched by Hg (II). • Nitrogen and sulfur co-doped carbon nanodots (CD) was synthesized. • The CD-QD@PU probe allows specific detection of Hg (II) down to 10.5 nM.

Tunable shape memory property polyurethane with high glass transition temperature composed of polycarbonate diols

AbstractA series of polyurethane (PU) copolymers was synthesized by 4,4‐Methylene diphenyl diisocyanate (MDI) with different polyols of polyether, polyether carbonate (PEC), and polycarbonate with the same molecular weight via a one‐step copolymerization process. The synthesized PU containing the ether carbonate groups exhibited a relatively higher glass transition temperature (Tg) above 45°C; in comparison, a value of 12.4°C for the polycarbonate sample and −22°C for the polyether sample was observed. The film made of PEC samples produced by solvent indicated an increment of Tg from 14.6 to 59.6°C after annealing for 6 h, which might be due to the rearrangement of chain structure, which led to an assembling of carbonate groups and resulted in a hindrance of chain mobility. For shape memory examination of the PU copolymers, all samples showed remarkable ability as recovery rate above 91% after 3 cycles test. PEC‐type PU polymers reveal potential high‐temperature micro shape memory material applications.