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

Abstract

The degradation behaviors including oxidation and hydrolysis of silicone modified polycarbonate urethanes were thoroughly investigated. These polyurethanes were based on polyhexamethylene carbonate (PHMC)/polydimethylsiloxane (PDMS) mixed macrodiols with molar ratio of PDMS ranging from 5% to 30%. It was proved that PDMS tended to migrate toward surface and even a small amount of PDMS could form a silicone-like surface. Macrophages-mediated oxidation process indicated that the PDMS surface layer was desirable to protect the fragile soft PHMC from the attack of degradative species. Hydrolysis process was probed in detail after immersing in boiling buffered water using combined analytical tools. Hydrolytically stable PDMS could act as protective shields for the bulk to hinder the chain scission of polycarbonate carbonyls whereas the hydrolysis of urethane linkages was less affected. Although the promoted phase separation at higher PDMS fractions lead to possible physical defects and mechanical compromise after degradation, simultaneously enhanced oxidation and hydrolysis resistance could be achieved for the polyurethanes with proper PDMS incorporation.

Hydrolysis‐resistant polyurethane elastomers synthesized from hydrophobic bio‐based polyfarnesene diol

“…The MC (water uptake) and physical properties can be used to evaluate the hydrolytic stability of PUEs . The results are presented in Table and Figure .…”

“…Polyurethanes (PUs), resulting from the polycondensation of polyisocyanate and polyols, have been widely used in various forms including flexible and rigid foams, adhesives, fibers, thermoplastic and thermosetting elastomers, and coatings . By mediating the chemical structures, molecular weight of polyols, hard segment content (HSC), synthesis method, and thermal history, PUs could be tailored to meet specific requirements such as excellent physical or damping properties, biocompatibility, flame retardancy, hydrophobicity or hydrophilicity, and abrasion and hydrolysis resistance . Among these requirements, hydrolysis resistance is the most critical when PUs are exposed to high humidity or in direct contact with aqueous environment during life cycle time, such as using as insulation layer of oil extraction pipes in offshore condition and implanted devices …”

State of the Art of Small‐Diameter Vessel‐Polyurethane Substitutes

“…For example, PCU synthesized from aliphatic polyols is more stable than from aromatic polyols, and its biostability increases with the increase in polyol molecular weight . When polydimethylsiloxane (PDMS) is introduced into PCU as a soft segment, it would form a silicone‐like surface due to a small amount of PDMS migrating toward surface, which could resist the attack of degradative species and improve the biostability . In the case of isocyanate compounds, MDI‐based PCU is more biostable than HDI‐based one in the presence of cholesterol enzyme because more hydrophobic surface and lower hysteresis of the former interfere with the molecular reorganization .…”

Improving the Oxidative Stability of Shape Memory Polyurethanes Containing Tertiary Amines by the Presence of Isocyanurate Triols

“…More recently, these structures have been used as cross-linkers in self-healing, shape memory, and other functional or advanced materials. We hypothesize that this structure could be used to develop more biostable SMP formulations. − More importantly, isocyanurates present a more similar material chemistry as opposed to altering the composition by incorporating ethers (which may oxidize in thermosets), carbonates (which may hydrolyze), siloxanes (which may exhibit significantly altered mechanical behavior and phase separation), or olefins (which may phase separate or be otherwise immiscible for processing). ,, …”

“…16−19 More importantly, isocyanurates present a more similar material chemistry as opposed to altering the composition by incorporating ethers (which may oxidize in thermosets), carbonates (which may hydrolyze), siloxanes (which may exhibit significantly altered mechanical behavior and phase separation), or olefins (which may phase separate or be otherwise immiscible for processing). 4,20,21 This paper presents the results from of utilizing the isocyanaurate functionality in aliphatic polyurethane SMPs with the intent of improving biostability and examining the roles of both diisocyanate and amino alcohol with regards to thermomechanical and biostability behavior. SMP compositions were varied to increase the material life span to predicted values of nearly 20 years compared to the 18 month life span of the controls.…”