Degradable Polyurethane Research Articles

Healable, degradable polyurethane elastomers with excellent mechanical properties based on multiple hydrogen bonds

AbstractDue to its comprehensive properties, polyurethane elastomer (PU) plays a vital role in ships, construction, transportation facilities, and other fields. However, it is challenging to design polyurethane elastomer materials with good mechanical properties, self‐healing ability, and degradable ability. Herein, a kind of polyurethane elastomer based on multiple hydrogen bond crosslinking was successfully synthesized by using polycaprolactone with substantial crystallization as a soft chain segment and introducing adipic dihydrazide (ADH) and U2‐diol (a ureido‐pyrimidinone with two hydroxyl groups at the end) to achieve ordered hydrogen bond assembly design and control. The elastomer has good tensile strength, healability, degradability, and solubility. The maximum tensile strength and toughness of the prepared polyurethane elastomer (PUAD) were 46.34 MPa and 687.66 MJ/m3, respectively. With the increase of U2‐diol content, the self‐repair efficiency was greatly enhanced. After seven repair cycles, the self‐repair efficiency can still reach 66.88%. In addition, the bacterial degradation test using Pseudomonas aeruginosa as a strain showed that PUAD film had excellent degradability. The dissolution test with N,N‐dimethylformamide (DMF) as solvent showed that the tensile strength was almost unchanged after three dissolutions.

Highly flexible, healable and degradable polyurethane phase change materials with exceptional mechanical properties for thermal regulation

Materials with multifunctionality, especially polymers based on dynamic covalent bonds, have attracted considerable interest due to their technological innovation. Nowadays, phase change materials (PCMs) are widely used in various cutting-edge fields, while strategies for simultaneous realization of their flexibility, self-healing, high mechanical properties and degradability are still highly anticipated. In this work, we have designed and constructed a multifunctional polyurethane phase change material (PU-PCM) by the incorporation of isocyanate-hydroxy coupling reaction, where the soft phase polyethylene glycol (PEG6K) serves as latent heat storage sectors, and triple boron-urethane bonds (t-BUBs) as dynamic cross-linkers in the hard segment provide healable ability, excellent mechanical properties, and degradability through the cooperative effect of ordered H-bonding interactions. As a result, the well-designed PU-PCM exhibits high flexibility, superior tensile strength (∼39.0 MPa), tensile strain (∼1425%), and toughness (∼324.0 MJ/m3), as well as excellent healable efficiency (∼90% at room temperature), and degradability in a mildly acidic solution. Also, the h-BN enhanced PU-PCM composite film can be used to cool the working CPU as the PEG6K chains embedded in the soft segments can work as a smart thermal-regulator to harvest the undesired heat from the surroundings.

Vanillin-Based Degradable Polyurethane Thermosets Demonstrating High Bio-Content and Mechanical Properties

Polyurethanes are widely used polymeric materials, but they are rarely biorenewable and degradable. Although some previously reported bio-based polyurethanes exhibit good thermal and mechanical properties, their bio-content is usually low, resulting from the only replacement of the diol monomer instead of the whole diol/diisocyanate pairs. In addition, traditional polyurethanes are often difficult to degrade, leading to environmental issues. To address these issues, we propose a solution by sourcing both the diols and isocyanates from biorenewable resources and introducing degradability into diols via the Tishchenko reaction, which is the disproportionation of two aldehydes to afford an ester bond with an atom economy of 100%. Commercially available bio-based vanillin was selected as the precursor for a vanillin-based diol (VBD) containing ester bonds. By reacting VBD with l-lysine diisocyanate (LDI) and trimethylolpropane (TMP) as a crosslinker, a series of bio-based thermosetting polyurethanes, VBD-TMPx, with high bio-based carbon content (>70.0%) were synthesized. The chemical structures and properties of monomers as well as polymers were characterized using nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile tests. The obtained VBD-TMPx polyurethanes exhibit comparable mechanical properties (σ = 32.0 MPa; E′ = 2.7 GPa) to commercial thermosetting polyurethanes and demonstrate higher toughness (34 MJ/m3) than previously reported bio-based analogues. Additionally, the inherent ester bond in the VBD monomer enables the complete degradation of VBD-TMPx in a 0.1 M NaOH solution (THF/H2O = 1:1, v/v) within 3.5 h. This greatly broadens the available end-of-life choices, including the recovery of the monomers. This study presents a facile approach for creating degradable polyurethane materials with high bio-content and mechanical properties.

Nanoceria-decorated Graphene Nanosheets Enhance Mechanical Properties and Bioactivity of a Degradable Polyurethane for Biomedical Applications

Nanoceria-decorated Graphene Nanosheets Enhance Mechanical Properties and Bioactivity of a Degradable Polyurethane for Biomedical Applications

Eco-friendly biodegradable polyurethane based coating for antibacterial and antifouling performance

Biofouling, which comprises the absorption of proteins and the adhesion of bacteria to the surface of living entities, is a severe concern for the maritime sector since it ultimately leads to hydrodynamic drag, resulting in a higher increase in fuel consumption. As a result, polymer resins are crucial in the marine sector for anti-biofouling coatings. In this work, the poly(caprolactone-ethylene glycol-caprolactone)-polyurethane (PECL-PU) are prepared through ε -caprolactone (CL), poly(ethylene glycol) (PEG), 4,4′-methylene bis(cyclohexyl isocyanate ) and 1,4 butanediol. Our study demonstrate that the PECL-PU copolymer degraded in artificial seawater (5.21%), enzymatic solution (12.63%), and seawater (13.75%) due to the presence of PEG segments in the laboratory-based test under static condition. Because the addition of PEG segments are increased the polymer's amorphous area and decreased the crystallization of the polycaprolactone (PCL) in the copolymer, as demonstrated by differential scanning calorimetry, X-ray diffraction, and water contact angle studies. Therefore, the hydrolysis rates of PECL-PU were higher than the caprolactone-co-polyurethane (CL-PU). The antifouling test showed that PECL-PU3 copolymer had about 90.29% protein resistance, 85.2% Escherichia coli ( E. coli ) reduction and 94.61% marine diatom Navicula incerta reduction comparison to the control. We have developed an eco-friendly and inexpensive promising degradable polyurethane for reduction of bacterial biofilm, which can preserve the formation of biofouling on marine coating under practical sea conditions.

Mechanically Strong and Tough Poly(urea-urethane) Thermosets Capable of Being Degraded under Mild Condition.

The development of degradable polymeric materials such as degradable polyurethane or polyurea has been much highlighted for resource conservation and environmental protection. Herein, a facile strategy of constructing mechanically strong and tough poly(urea-urethane) (PUU) thermosets that can be degraded under mild conditions by using triple boron-urethane bonds (TBUB) as cross-linkers is demonstrated. By tailoring the molecular weight of the soft segment of the prepolymers, the mechanical performance can be finely controlled. Based on the cross-linking of TBUB units and hydrogen-binding interactions between TBUB linkages, the as-prepared PUU thermosets have excellent mechanical strength of ≈40.2MPa and toughness of ≈304.9MJm-3 . Typically, the PBUU900 strip can lift a barbell with 60000 times its own weight, showing excellent load-bearing capacity. Meanwhile, owing to the covalent cross-linking of TBUB units, all the PUU thermosets show initial decomposition temperatures over 290°C, which are comparable to those of the traditional thermosets. Moreover, the TBUB cross-linked PUU thermosets can be easily degraded in a mild acid solution. The small pieces of the PBUU sample can be fully decomposed in 1m HCl/THF solution for 3.5h at room temperature.

Evaluation of electrospun PCL diol-based elastomer fibers as a beneficial matrix for vascular tissue engineering

The main reason for the failure of artificial blood vessel transplantation is the lack of mechanically matched materials with excellent blood compatibility. The electrospun biodegradable polyurethane (BPU) fibers with micro to nanoscale topography and high porosity similar to the natural extracellular matrix (ECM) is one of the most suitable options for vascular graft. In our recent study, we prepared a series of PCL-based BPU fibers by combining two-step solution polymerization and electrospinning. SEM, 1H NMR, ATR-FTIR, XRD, TG, water contact angle, and mechanical tests were used to analyze the chemical structure, microstructure, thermal properties, surface wettability, degradation, cytocompatibility, and hemocompatibility in vitro of electrospun fibers. The results show that the synthesized H-PEUU, L-PEUU, H-PEEUU, and L-PEEUU have different crystalline properties, thus exhibiting distinctive thermal, mechanical, and degradation properties. Although the existence of the molecular structure of LDI and PEG600 in fibers can promote cell proliferation and migration unilaterally, the microstructure of the material is also the main factor affecting the biocompatibility of cells. The results suggest that the designed PCL-based degradable polyurethane electrospun fiber is expected to be applied to vascular tissue engineering.

Oxidative Degradation of Thermosets Based on Thioketal Cleavable Linkages in Aqueous Environment

Thermosets are rigid, infusible, and unmolded materials containing three-dimensional (3D) cross-linked structures. They are considered a fundamental pillar in the international economy, which are produced by 65 million tons annually. The responsive cross-linking moieties provide the thermosets characterized with outstanding physicochemical properties such as stiffness, degradability, and chemical and thermal resistance. We prepared degradable thermoset materials using thioketal (TK) cross-linkers, which underwent main-chain or side change degradation in the presence of hydrogen peroxide in water. TK cross-linkers at different concentrations (5, 10, and 20% wt %) were polymerized with 2-hydroxyethyl acrylate (HEA) or with 2-hydroxyethyl methacrylate (HEMA) and 1-vinyl-2-pyrrolidone (PD) to produce cross-linked poly(HEA) and poly(HEMA-PD) by free radical polymerization, respectively. The resultant polymer materials completely degraded in hydrogen peroxide/water (3–30%, vol). Using isophorone diisocyanate, we also produced degradable polyurethane based on TK-bearing diol. We prepared a 3D degradable thermoset using the Direct-Ink-Writing (DIW) 3D printing technology, which was charged by diethylene glycol diacrylate (15%, wt %) and a prepolymer (isophorone diisocyanate terminated by acrylate moieties) containing diol-thioketal linkage (15%, wt %). Finally, we found that TK-poly(HEA) underwent microbial degradation by Lactobacillus jensenii at 37 °C, which indicates a benign eco-friendly effect.

Synthesis and characterization of polyurethane with poly(ether-ester) diols soft segments consisted by ether and ester linkages in one repeating unit

Development of controllable, versatile and robust degradable polyurethane (PU) is of continued attraction regarding its wide application in the field of biology and medicine. Herein, new degradable poly(ether-ester-urethane) (PEEU) with amorphous and hydrophilic poly(1,5-dioxepan-2-one) (PDXO) diols as the soft segments and 4,4-diphenylmethane diisocyanate (MDI) and butane-1,4-diols (BDO) as the hard segments was synthesized by the one-shot two -step method in a controllable manner. The degradation behavior of PEEU with various compositions in vitro was investigated by observing the changes of weight loss, molecular weight and surface morphology during the 140 days of degradation. The weight loss and degradation rate of PEEU were faster than that of PU with semi-crystallized poly(ε-caprolactone) diols as soft segments and a surface to bulk degradation process was observed by scanning electron microscopy (SEM). In addition, the weight loss decreased by increasing the hard segments composition and the weight loss was mainly from the hydrolysis of ester linkages.

A novel bioactive polyurethane with controlled degradation and L-Arg release used as strong adhesive tissue patch for hemostasis and promoting wound healing.

Effective strategy of hemostasis and promoting angiogenesis are becoming increasingly urgent in modern medicine due to millions of deaths caused by tissue damage and inflammation. The tissue adhesive has been favored as an optimistic and efficient path to stop bleeding, while, current adhesive presents limitations on wound care or potential degradation safety in clinical practice. Therefore, it is of great clinical significance to construct multifunctional wound adhesive to address the issues. Based on pro-angiogenic property of l-Arginine (L-Arg), in this study, the novel tissue adhesive (G-DLPUs) constructed by L-Arg-based degradable polyurethane (DLPU) and GelMA were prepared for wound care. After systematic characterization, we found that the G-DLPUs were endowed with excellent capability in shape-adaptive adhesion. Moreover, the L-Arg released and the generation of NO during degradation were verified which would enhance wound healing. Following the in vivo biocompatibility was verified, the hemostatic effect of the damaged organ was tested using a rat liver hemorrhage model, from which reveals that the G-DLPUs can reduce liver bleeding by nearly 75% and no obvious inflammatory cells observed around the tissue. Moreover, the wound care effect was confirmed in a mouse full-thickness skin defect model, showing that the hydrogel adhesive significantly improves the thickness of newly formed dermis and enhance vascularization (CD31 staining). In summary, the G-DLPUs are promising candidate to act as multifunctional wound care adhesive for both damaged organ and trauma.

A bioinspired Janus polyurethane membrane for potential periodontal tissue regeneration.

Guided tissue regeneration (GTR) is the main therapeutic method for periodontal tissue regeneration. The key to the GTR strategy is the membrane which can assist the reconstruction of bone tissue in the periodontal defect and prevent the migration of epithelium and fibroblasts to the defect. However, the existing periodontal membrane cannot effectively promote periodontal tissue regeneration due to the limited bioactivity and physicochemical function. Here, we developed a bioinspired degradable polyurethane membrane with Janus surface morphology by integrating bioactive dopamine (DA) and an antibacterial Gemini quaternary ammonium salt (QAS). The Janus surface of the membrane is fabricated through spontaneous microphase separation, resulting from the different migration of functional segments between the air-contact upper surface with enriched antibacterial QAS and the substrate-contact bottom with enriched bioactive DA. The smooth surface of the upper membrane used to face the soft tissues can reduce cell adhesion to suppress the migration of fibroblasts, while the rough surface with a topological micro-pit structure of the bottom side facing the bone has excellent function of autonomic mineralization and cell adhesion to promote bone tissue reconstruction. In addition, the membrane containing the antibacterial QAS shows excellent antibacterial effect on common oral pathogens, such as S. aureus and S. mutans. Moreover, the specific dopamine group also endows the membrane with excellent antioxidant efficiency. In vivo research shows that this Janus polyurethane membrane can effectively promote periodontal tissue regeneration in a rat periodontal defect model. Combined with its excellent mechanical properties and biocompatibility, the polyurethane membrane is a promising material for potential periodontal tissue regeneration.

Preparation of degradable castor oil-based waterborne polyurethane with tannic acid as crosslinking agent and its application on leather surface coating

In recent years, the types and quantities of polyurethane products have increased day by day. However, traditional petroleum-based water-based polyurethanes not only have the problem of difficult waste disposal, but also accelerate the depletion of petroleum materials. Herein, an eco-friendly polymer was successfully prepared by introducing tannic acid (TA) into castor oil-based waterborne polyurethane (WPU). The effects of the incorporation of TA, a bio-based material, on the particle size of the resulting polyurethane (PU) dispersion, and the thermal performance, mechanical properties, and hydrophobicity of PU membranes were systematically investigated. Finally, ATR-FTIR and SEM of cured films after degradation were measured to characterize the degradation ability of the membranes. It was found that the tensile strength of the samples is improved from 12.67 to 19.57 MPa with the TA content increasing from 0 to 1.5%, nevertheless their elongation at break declines from 306.51 to 237.12%. A noteworthy increase in the glass transition temperature (Tg) was exhibited by using DSC and DMA for the resulting PU films with increasing the TA content. Besides, the improvement in the water absorption of the blend films decreases from 14.5 to 10.2% according to the advantage of TA increasing the degree of cross-linking of the system. After 120 days of degradation, it can be seen that the urethane bond and the aliphatic ester bond played a vital role in the degradation process through the infrared of the degraded films. At the same time, the introduction of TA improves the degradation performance of WPU films. What is more, the application of WPU dispersions containing tannins on the leather surface shows excellent comprehensive performance, which means that WPU dispersions have potential applications as leather finishing agents. This work takes advantage of two kinds of bio-based materials, the mass of bio-based materials accounts for 57% of the total mass, which not only shortens the utilization of petroleum resources, but also effectively resolved the problem that poor quality of castor oil-based WPU and traditional waste is difficult to degrade, improving the commercial value of castor oil-based PU.

PH-Responsive and degradable polyurethane film with good tensile properties for drug delivery in vitro

In this paper, we synthesized a new type of pH-responsive block polyurethane (PMCU) through the condensation polymerization of N-methyldiethanolamine (MDEA), poly(ε-caprolactone) and 4,4′-dicyclohexylmethane diisocyanate. The chemical structure of the PMCU were characterized, and the influence of MDEA content on the physicochemical properties of the casted PMCU films were studied detailly. The tensile test demonstrated the good tensile properties of the PMCU films with the breaking strain of 983–425% and the ultimate strength of 11.7–31.2 MPa. The tertiary amine groups and polyester segments endowed the material with pH sensitivity and hydrolytic degradability, respectively. The pH responsiveness of the films was confirmed from the enhanced equilibrium swelling ratio (ESR) with decreasing pH value of the medium, and the ESR in acidic condition (pH 1.5) was much higher than that in neutral (pH 7.0) and basic (pH 12.0) conditions. The studies of drug sustained-release in vitro at different pH indicated a pH-dependent release efficiency, which was closely related with the ESR and almost unaffected by the slow hydrolytic degradation. In addition, the cytotoxicity assay showed that the PMCU had good cytocompatibility to L929 cells. This study showed that pH-responsive promising platform for targeted drug delivery in the biomedical areas.

Achieving morphological evolution and interfacial enhancement in fully degradable and supertough polylactide/polyurethane elastomer blends by interfacial stereocomplexation

The degradable polyurethane elastomers containing poly (L-lactide) (L-PU) and poly (D-lactide) (D-PU) were synthesized and incorporated in commercial PLLA as the toughening modifier. The stereocomplexation of PLA (sc-PLA) is successfully achieved at the interface of PU and PLLA domains in a single melt-blending process. The morphology and matrix crystallization in PLLA/D-PU blends is significantly improved by the presence of interfacial sc-PLA, showing morphological evolution to strip-shaped dispersion of PU phase and remarkable acceleration in matrix crystallization kinetics. After incorporating D-PU, the mechanical properties of blends are improved by interfacial sc-PLA, demonstrating that the notched Izod impact strength increases from 11.8 ± 3.1 KJ/m2 of PLLA/L-PU15 to 27.0 ± 5.8 KJ/m2 of PLLA/D-PU15 and even greater enhancement after thermal annealing is achieved. By observing the morphology of the impact fracture surface, the toughening mechanism of D-PU is investigated, revealing that the superior interfacial strength facilitates shear yielding of non-annealed sample and further prohibits de-bonding of rubber phase after thermal annealing. Hydrolysis tests in alkaline environment show that although interfacial sc-PLA can retard the hydrolysis rate, the blends still experience rapid weight loss to achieve full degradation. This work provides a highly effective strategy to toughen PLLA without sacrificing its degradability.

One-Shot Preparation of Thermoresponsive Comb Polyurethane Hydrogel for Both Excellent Toughness and Large Volume Switching.

Thermoresponsive degradable polyurethane (PU) hydrogels are expected as the next-generation biomedical devices, although they have an important trade-off relationship between toughness and thermoresponsive properties. Tough and thermoresponsive comb PU hydrogels are prepared by one-shot poly-addition between hexamethylene diisocyanate, triethylene glycol tartrate ester, poly(ethylene glycol) 300 (PEG300), and glycerol. The swelling ratio change between 4 and 40°C decreases as the proportion of PEG300 increases and is maintained at 600% switching within 30% PEG300. Moreover, the one-shot preparation of comb PU hydrogel with PEG300 improves toughness up to 100 times compared to the original comb PU hydrogel. Rheological analysis suggests that the bimodal toughening phenomenon for the proportion of PEG300 is due to the network structure and the hydrophobic aggregation domain. This simple toughening method using a heteronetwork based on the kinetic difference of step-growth PU is expected to apply to other chemical structures.

Evaluation of a bone filler scaffold for local antibiotic delivery to prevent Staphylococcus aureus infection in a contaminated bone defect

We previously reported the development of an osteogenic bone filler scaffold consisting of degradable polyurethane, hydroxyapatite, and decellularized bovine bone particles. The current study was aimed at evaluating the use of this scaffold as a means of local antibiotic delivery to prevent infection in a bone defect contaminated with Staphylococcus aureus. We evaluated two scaffold formulations with the same component ratios but differing overall porosity and surface area. Studies with vancomycin, daptomycin, and gentamicin confirmed that antibiotic uptake was concentration dependent and that increased porosity correlated with increased uptake and prolonged antibiotic release. We also demonstrate that vancomycin can be passively loaded into either formulation in sufficient concentration to prevent infection in a rabbit model of a contaminated segmental bone defect. Moreover, even in those few cases in which complete eradication was not achieved, the number of viable bacteria in the bone was significantly reduced by treatment and there was no radiographic evidence of osteomyelitis. Radiographs and microcomputed tomography (µCT) analysis from the in vivo studies also suggested that the addition of vancomycin did not have any significant effect on the scaffold itself. These results demonstrate the potential utility of our bone regeneration scaffold for local antibiotic delivery to prevent infection in contaminated bone defects.

Synthesis and characterization of caprolactone based polyurethane with degradable and antifouling performance

In this work, a degradable polyurethane composed of caprolactone (CL) and L-Lactide (LLA) as soft segments, and 4,4′-methylenebis(cyclohexyl isocyanate) (H12MDI) and polytetramethylene ether glycol (PTMEG) as hard segments, was prepared. Hydrolytic degradation experiment revealed that the degradable polyurethane (PU) could be degraded in artificial seawater. It also showed that caprolactone-co-polyurethane (CL-PU) copolymer with higher crystallinity degraded much slower in artificial seawater. However, the introduction of LLA resulted in an increase in the hydrophilicity and reduction in the crystallinity of degradable PU, as demonstrated by the contact angle analysis. The result of the scanning electron microscope showed that the surface of degradable PU renewed under static condition. Moreover, degradable PU was able to be used as a carrier, and it controlled the release rate of 4, 5-dichloro-2-octyl-isothiazolone (DCOIT). The anti-diatom (Navicula incerta) test demonstrated that the (caprolactone-co-L-lactide)-co-polyurethane 4 (CL/LAx-PU4) with DCOIT contents prevented the adhesion of diatom Navicula incerta (88.37% reduction) due to their self-polishing and the release of antifoulants. Therefore, the degradable PU consisted of CL, LLA, and DCOIT could be a durable resin with good antifouling activity for the application in the marine anti-biofouling field.

Microstructure and Mechanical Properties of PU/PLDL Sponges Intended for Grafting Injured Spinal Cord.

Highly porous, elastic, and degradable polyurethane and polyurethane/polylactide (PU/PLDL) sponges, in various shapes and sizes, with open interconnected pores, and porosity up to 90% have been manufactured. They have been intended for gap filling in the injured spinal cord. The porosity of the sponges depended on the content of polylactide, i.e., it decreased with the increase of polylactide content. The rise of polylactide content caused an increase of Young modulus and rigidity as well as a more complex morphology of the polyurethane/polylactide blends. The mechanical properties, in vitro toxicity, and degradation in artificial cerebrospinal fluid were tested. Sponges underwent continuous degradation with varying degradation rates depending on the polymer composition. In vitro cell studies with fibroblast cultures proved the biocompatibility of the polymers. Based on the obtained results, the designed PU/PLDL sponges appeared to be promising candidates for bridging gaps within injured spinal cord in further in vitro and in vivo studies.

Evaluation of a novel biodegradable ureteral stent produced from polyurethane and magnesium alloys.

Indwelling ureteral stents represent a very frequently used procedure in urological clinical practice that ensures the drainage of urine from the upper urinary tract. However, the stents could result in many stent-associated complications, such as encrustation and patient discomfort. We developed a new type of biodegradable ureteral stents produced from degradable polyurethane and magnesium alloys. In the present study, we investigated the biocompatibility and the property of degradation of the biodegradable ureteral stents. We evaluated the cytotoxicity of biodegradable ureteral stent by the MTT assay in vitro. The rabbit dorsal muscle embedding test was used to assess the biocompatibility of the degradable stents. Inflammation and fibrosis of muscle tissue were noted to evaluate compatibility at 1, 2, 4, 6 weeks after stents implanted in muscle. The degradation of the biodegradable ureteral stents was assessed by measuring the weight loss of the samples in AUS (artificial urine solution). For validating the degradation property of degradable stents in vivo, we inserted a degradable stent or a conventional biostable stent into Bama pigs. Furthermore, blood studies, liver function tests, renal function tests, urine studies, and computerized tomography (CT) were performed postoperatively. Our study confirms that the degradable polyurethane-based biodegradable ureteral stent has good biocompatibility. Our biodegradable ureteral stents were completely degraded within 4 weeks and provided a better ability of drainage than conventional stents. They hold promise for decreasing the need for a secondary procedure and stent related morbidity, such as infections.

High-Performance, Biobased, Degradable Polyurethane Thermoset and Its Application in Readily Recyclable Carbon Fiber Composites

Carbon fiber (CF) reinforced polyurethane (PU) composites have attracted increasing attention in recent years. It is still a challenge to recycle the CF reinforced composites, and there is no repor...