Superior anti-biofouling properties of mPEG-modified polyurethane networks via incorporation of a hydrophobic dangling chain

Abstract PEG-modification is a proven method to enhance the hydrophilicity, protein resistance, and anti-biofouling properties of polymer coatings. It is considered as the gold standard interfacial modification technique such that the higher PEG content, the higher hydrophilicity, and lower protein adsorption, i.e., the initial stage of the biofouling process. Nevertheless, increasing the PEG content causes a higher water uptake, which declines the polymer mechanical strength and increases its hydrolytic degradation rate. Thus, an effective strategy to produce a limited-water-absorbing PEG-modified polymer is to force the majority of PEG molecules to migrate towards the interfacial region while the modification takes place. In the current paper, we report the synthesis and characterization of crosslinked polycarbonate-based polyurethanes (PU) containing methoxy polyethylene glycol (mPEG) dangling chains. We show that the simultaneous incorporation of a limited amount of a low-surface-energy dangling chain, i.e., 1-octadecanol (oDEC), along with mPEG, results in a considerably higher mPEG surface concentration, according to X-ray photoelectron spectroscopy (XPS), and a significantly lower water contact angle (WCA), up to 45° lower. We also put forward a reasonable mechanism for our outstanding observation and verified it through extensive experiments, e.g., dynamic WCA, Atomic force microscopy (AFM), and XPS. Moreover, we outline a delicate dynamic WCA experimental protocol, by which the smart and responsive behavior of our coatings is illustrated. Eventually, we examined the mixed hydrophobic/hydrophilic dangling chains strategy for low-protein adsorption applications, in which a great potential has been discovered.