Aliphatic polycarbonate-based polyurethane elastomers and nanocomposites. II. Mechanical, thermal, and gas transport properties

Bridging polymer architecture, printability, and properties by digital light processing of block copolycarbonates

CO2-based aliphatic polycarbonates (aPCs), produced through the alternating copolymerization of epoxides with CO2, present an appealing option for sustainable polymeric materials owing to their renewable feedstock and degradable characteristics. An ongoing challenge in working with aPCs is modifying their mechanical properties to meet specific demands. Herein, we report that monomer ratio and polymer architecture of aPCs impact not only printability by digital light processing (DLP) additive manufacturing, but also dictate the thermomechanical and degradation properties of the printed objects. We found that block copolymers exhibit tailorable thermomechanical properties ranging from soft elastomeric to strong and brittle as the proportion of hard blocks increases, whereas the homopolymer blend failed to print objects and statistical copolymers delaminated or overcured, displaying the weakest mechanical properties. In addition, the hydrolytic degradation of the prints was demonstrated under various conditions, revealing that BCP prints containing a higher proportion of hard blocks had slower degradation and that statistical copolymer prints degraded more slowly than their BCP counterparts. This study underscores that polymer composition and architecture both play key roles in resin printability and bulk properties, offering significant prospects for advancing sustainable materials in additive manufacturing through polymer design.

Porous polycaprolactone and polycarbonate poly(urethane urea)s via emulsion templating: structures, properties, cell growth

Macroporous, emulsion-templated, linear poly(urethane urea) elastomers were synthesized from polyols (poly(ε-caprolactone)s or polycarbonates) and a diisocyanate. Growing cells adhered to the walls, spread, and penetrated into the porous structures.

The Influence of Nanofiller Shape and Nature on the Functional Properties of Waterborne Poly(urethane-urea) Nanocomposite Films

A series of waterborne polycarbonate-based poly(urethane-urea) nanocomposite films were prepared and characterized. An isocyanate excess of 30 mol% with respect to the hydroxyl groups was used in the procedure, omitting the chain-extension step of the acetone process in the dispersion preparation. The individual steps of the synthesis of the poly(urethane-urea) matrix were followed by nuclear magnetic resonance (NMR) spectroscopy. The nanofillers (1 wt% in the final nanocomposite) differed in nature and shape. Starch, graphene oxide and nanocellulose were used as representatives of organic nanofillers, while halloysite, montmorillonite, nanosilica and hydroxyapatite were used as representatives of inorganic nanofillers. Moreover, the fillers differed in their shape and average particle size. The films were characterized by a set of methods to obtain the tensile, thermal and surface properties of the nanocomposites as well as the internal arrangement of the nanoparticles in the nanocomposite film. The degradation process was evaluated at 37 °C in a H2O2 + CoCl2 solution.

Recent developments in the field of barrier and permeability properties of segmented polyurethane elastomers

Polyurethane (PU) elastomers represent an important class of segmented copolymers. Thanks to many available chemical compositions, a rather broad range of chemical, physical, and biocompatible properties of PU can be obtained. These polymers are often characterized by high tensile and tear strength, elongation, fatigue life, and wear resistance. However, their relatively high permeability towards gases and water as well as their biocompatibility still limits the PU’s practical application, especially for biomedical use, for example, in implants and medical devices. In this review, the barrier and permeability properties of segmented PUs related to their chemical structure and physical and chemical properties have been discussed, including the latest developments and different approaches to improve the PU barrier properties.