Polyurethane Dispersions with Peptide Corona: Facile Synthesis of Stimuli-Responsive Dispersions and Films

Abstract

Peptide-polymer hybrid particles of submicron size yielding stimuli-responsive macroscopic films are presented. A thermoplastic polyurethane (PU) carrying polysiloxane and polyester soft segments serves as core material to obtain flexible, yet semicrystalline films with temperature-sensitivity. The synthesis is based on the high-sheer emulsification of isocyanate-terminated PU prepolymers, which in our model system purposefully lack any ability of colloidal self-stabilization. While emulsification in water leads to immediate coagulation, stable dispersions of polyurethane nanoparticles were formed in aqueous solutions of a hydrolyzed protein from wool. A comparison of dispersion and film properties to nonreactive, otherwise identical dispersions suggests covalent attachment of the peptide to the PU backbone. We show that the colloidal stability of the hybrid particles is completely governed by the peptide corona, and hence pH-triggered coagulation can be employed to induce particle deposition and film formation. Differential scanning calorimetry confirms partial crystallinity in the film and reveals strongly modified crystallization behavior due to the peptide.

Phosphonic Acid-Functionalized Polyurethane Dispersions with Improved Adhesion Properties

“…This is further supported by the rather similar conversions obtained for samples using the alternative method of reagent addition and pH increase in the aqueous phase prior to dispersing and the much lower conversion obtained with AMPA, the other end-cap reagent investigated, which possesses a more hydrophilic structure (see Figure S2). It can further be noted that surprisingly slow reaction kinetics of NCO-functional PUDs with nucleophiles have been observed before from our group, although a quite different system was investigated, namely, the preparation of PUDs stabilized with a protein corona . However, the results indicate that, with more complex, partially charged end-capping reagents of pronounced hydrophilicity, interfacial adsorption can dominate the reaction.…”

“…Through addition of a slight excess of isocyanate with regard to alcohol functionalities, a prepolymer of moderate molecular weight with NCO end groups is obtained. These end groups can be used for a chain extension under aqueous conditions (after dispersion) to increase the molecular weight of the PU chains and/or for an end-cap in order to introduce a desired functionality into the polymer structure. ,, For this procedure, highly nucleophilic chain extenders and/or functionalization agents are required in order to kinetically subdue the unwanted side reaction with water. For the same reason, most systems solely rely on aliphatic polyisocyanates because they are less sensitive toward water.…”

“…Polyester segments capable of crystallizing were included in order to provide a temperature-induced change in modulus. Indeed, the incorporation of crystalline moieties is a well-known method to provide a reversible setting mechanism in the film. , Furthermore, since crystallization in the film is strongly dependent upon polymer composition and separation between hard and soft segments in PUs, an analysis of the heat flow diagrams often gives valuable information about the film composition …”

“…They further display an extraordinarily rich chemistry due to the reversibility of isocyanate-based bonds (urethane, urea, biuret, allophanate, etc.) and allow for facile modification reactions, e.g., to integrate thermal- or UV-curing capabilities. , In the recent past, due to a rising environmental concern and increasingly stringent governmental regulations restricting the production of volatile organic compounds (VOCs), researchers have begun to shift their focus from traditional, solvent-based PUs to aqueous PUD systems. , In particular, complex structures may be obtained which provide, e.g., self-stabilization and specific surface functionalization of the dispersions and semicrystallinity in the film. , Surprisingly, only a few reports on PUDs comporting phosphorus groups (P-PUDs) can be found in the literature. For flame retardancy purposes, a polyphosphate polyol , and a phosphorus spiro compound were utilized .…”

Simultaneous Improvement of Oxidative and Hydrolytic Resistance of Polycarbonate Urethanes Based on Polydimethylsiloxane/Poly(hexamethylene carbonate) Mixed Macrodiols

“…Polyurethanes (PUs) are block copolymers comprising soft segments (SS) and hard segments (HS). Via tuning the chemical composition of HS and SS, versatile PUs could be obtained with a combination of excellent mechanical properties, good biocompatibility as well as processability, making them promising candidates in biomedical applications. − Particularly, the documented strength, durability, flexibility, and biostability extend the use of PUs in long-term implantable medical devices. However, PUs were observed to be degraded in vivo mainly through hydrolytic and oxidative degradation .…”