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)-p olyurethane(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.

THE DEGRADATION AND BIOCOMPATIBILITY OF WATERBORNE BIODEGRADABLE POLYURETHANES FOR TISSUE ENGINEERING

To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes （PEGPUs） with low degree of crosslinking was synthesized using IPDI, BDO and L-lysine as hard segments, PCL and PEG as soft segment. The bulk structures and properties of the prepared polyurethanes were characterized by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC）, tensile mechanical tests and water contact angle （WCA） measurements. The degree of microphase separation was slightly improved because of the lowered crosslinking degree of these PEGPUs in comparison with the high cross-linking degree samples, leading to good mechanical properties, as indicated by DSC and stress-strain data. Moreover, biodegradability of the polyurethanes was evaluated in phosphate buffer solutions （PBS） under different pH values and enzymatic solution at pH 7.4 through weight loss monitoring. The results suggested that the degradation of these PEGPUs was closely related to their bulk and surface properties. And the degradation products didn＇t show apparent inhibition effect against fibroblasts in vitro. These studies demonstrated that the waterborne biodegradable polyurethanes could find potential use in soft tissue engineering and tissue regeneration.

Polyurethane as substrate for fungal strains

Polyurethane is a versatile plastic with several industrial applications in the modern life, but it is considered as a very recalcitrant material. Biodegradation of this plastic has been poorly explored, and most of the studies that have been published focus on bacterial enzymes. In this work, some fungi with the capacity of growing with polyurethane foam as nutrient source were isolated from sands contaminated with this plastic and from DIA/UAdeC collection, testing their ability to grow on polyurethane as sole carbon and nitrogen sources and their enzymatic activities were determined in specific media as well as their invasion capacity on polyurethane agar plates. 22 fungal strains demonstrated their capacity of growing on polyurethane. Among the enzymatic activities evaluate, the most common was the urease activity (95% of the strains).Protease, esterase and laccase activities were present in 86%, 50% and 36% respectively. The great ability of the isolated fungal strains to use polyurethane foam as nutrient opens an important opportunity to study at detail the biodegradation of this plastic, with clear implications in cell biology and environmental technology.

Rational design of biodegradable thermoplastic polyurethanes for tissue repair

As a type of elastomeric polymers,non-degradable polyurethanes(PUs)have a long history of being used in clinics,whereas biodegradable PUs have been developed in recent decades,primarily for tissue repair and regeneration.Biodegradable thermoplastic(linear)PUs are soft and elastic polymeric biomaterials with high mechanical strength,which mimics the mechanical properties of soft and elastic tissues.Therefore,biodegradable thermoplastic polyurethanes are promising scaffolding materials for soft and elastic tissue repair and regeneration.Generally,PUs are synthesized by linking three types of changeable blocks:diisocyanates,diols,and chain extenders.Alternating the combination of these three blocks can finely tailor the physio-chemical properties and generate new functional PUs.These PUs have excellent processing flexibilities and can be fabricated into three-dimensional(3D)constructs using conventional and/or advanced technologies,which is a great advantage compared with cross-linked thermoset elastomers.Additionally,they can be combined with biomolecules to incorporate desired bioactivities to broaden their biomedical applications.In this review,we comprehensively summarized the synthesis,structures,and properties of biodegradable thermoplastic PUs,and introduced their multiple applications in tissue repair and regeneration.A whole picture of their design and applications along with discussions and perspectives of future directions would provide theoretical and technical supports to inspire new PU development and novel applications.

Preparation and Physicochemical Properties of Hydroxyapatite/Polyurethane Nanocomposites

In this study, nanohydroxyapatite/polyurethane （nHA/PU） composites with various contents of methoxy- poly（ethylene glycol） modified nHA （0 wt%, 10 wt%, 20 wt% and 30 wt%） were prepared by solution blending process. The physicochemical properties of the composite membranes were investigated by Fourier transform infrared spectroscopy （FTIR）, X-ray diffraction （XRD）, Transmission electronic microscopy （TEM）, Differential scanning calorimetry （DSC）, Thermo gravimetric analysis （TGA） and tensile tests. TEM photos of the nanocomposites showed that the nHA was uniformly dispersed in the polymer matrix. The membrane with 10 wt% nHA showed the highest tensile strength which was about 75% higher than that of the pure PU membrane. However, the tensile strength decreased when high content （above 20 wt%） fillers were added, which was still higher than that of pure PU. TGA measurements suggested that the thermal stability of the membranes was improved owing to nHA fillers. XRD and DSC results illustrated that the crystallinity of PU soft segments decreased with the increasing content of nanoparticles in the composites.