Waterborne Polyurethane Dispersions and Thin Films: Biodegradation and Antimicrobial Behaviors.

Biodegradable and antimicrobial waterborne polyurethane dispersions (PUDs) and their casted solid films have recently emerged as important alternatives to their solvent-based and non-biodegradable counterparts for various applications due to their versatility, health, and environmental friendliness. The nanoscale morphology of the PUDs, dispersion stability, and the thermomechanical properties of the solid films obtained from the solvent cast process are strongly dependent on several important parameters, such as the preparation method, polyols, diisocyanates, solid content, chain extension, and temperature. The biodegradability, biocompatibility, antimicrobial properties and biomedical applications can be tailored based on the nature of the polyols, polarity, as well as structure and concentration of the internal surfactants (anionic or cationic). This review article provides an important quantitative experimental basis and structure evolution for the development and synthesis of biodegradable waterborne PUDs and their solid films, with prescribed macromolecular properties and new functions, with the aim of understanding the relationships between polymer structure, properties, and performance. The review article will also summarize the important variables that control the thermomechanical properties and biodegradation kinetics, as well as antimicrobial and biocompatibility behaviors of aqueous PUDs and their films, for certain industrial and biomedical applications.

Preparation of Nanoscale Semi-IPNs with an Interconnected Microporous Structure via Cationic Polymerization of Bio-Based Tung Oil in a Homogeneous Solution of Poly(ε-caprolactone).

Nanoscale semi-interpenetrating polymer networks of bio-based poly(ε-caprolactone) (PCL) and polymerized tung oil have been prepared via in situ cationic polymerization and compatibilization in a homogeneous solution. This novel blending technique produced a nanoscale morphology of poly(ε-caprolactone) with average particle sizes as small as 100 nm dispersed in a cross-linked tung oil matrix for 20 and 30 wt % PCL blend compositions. In addition, the exothermic cationic polymerization of tung oil in the presence of the PCL homogeneous solution created a microporous morphology with open three-dimensional interconnected cluster structures. The porous morphology was found to be composition-dependent (the pore size and interconnectivity decreased with increasing PCL content in the blend). The values of the cross-link density and storage modulus in the glassy state for fully cured samples increased significantly and reached a maximum for the 20 wt % PCL blend. This simple, versatile, low-cost strategy for preparing nanoscale and interconnected three-dimensional cluster structures with a microporous morphology and desired properties should be widely applicable for new polymer systems.

Unexpected tackifiers from isosorbide.

Molecularly well-defined tackifiers with up to 100 % bio-content were prepared from isosorbide and various cyclic anhydrides. These tackifiers are tacky over a broad temperature range and exhibit high maximum tack (ca. 2000 kPa). Structural modifications shift the temperature at which maximum tack is observed and change the viscosity of the tackifiers.

Biobased polyurethanes prepared from different vegetable oils.

In this study, a series of biobased polyols were prepared from olive, canola, grape seed, linseed, and castor oil using a novel, solvent/catalyst-free synthetic method. The biobased triglyceride oils were first oxidized into epoxidized vegetable oils with formic acid and hydrogen peroxide, followed by ring-opening reaction with castor oil fatty acid. The molecular structures of the polyols and the resulting polyurethane were characterized. The effects of cross-linking density and the structures of polyols on the thermal, mechanical, and shape memory properties of the polyurethanes were also investigated.