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

Abstract

Shape memory polymers (SMPs) have been proposed for a wide variety of biomedical applications, such as cerebrovascular aneurysm occlusion; however, risks associated with degradation byproduct formation have raised the need for more biostable formulations. In this study, the use of cyclized isocyanates, in the form of isocyanurate-containing alcohols, was examined in aliphatic SMPs as a method of improving biostability. The materials were investigated for thermomechanical behavior, shape memory response, biostability, and cytocompatibility. In vitro experiments indicated that the isocyanurate-containing porous SMPs possess similar mechanical properties, albeit with improved toughness and no impact to strain recovery shape memory behavior, although atmospheric water uptake increased. Importantly, SMP life span was greatly increased, as control materials were demonstrated to fully degrade in accelerated testing by 25 days, while the modified materials retain more than 90% of their original mass. These modifications also resulted in increased cytocompatibility, indicating that this method may be used for translating biomaterials toward clinical applications.

Terpene- and terpenoid-based polymeric resins for stereolithography 3D printing

“…The displayed strains at break are relatively large for highly crosslinked thermosetting materials, particularly for the limonene system after post-curing at high temperatures. 34,36,37 Strain at break was found to correlate with the post-polymerisation post-cure temperature (ESI Fig. S17 †), with limonene displaying approximately 180% strain before break after post-curing at 120°C (after irradiation), but after a 30°C post-curing step of the same duration, fracture strain was only 77.3% (55.9% strain for the prepolymer) ( Fig.…”

Mesoporous Silica Nanoparticles to Tune Oxidative Degradation Rates in Composite Shape Memory Polymers

“…This distinct shoulder at 1458 cm -1 may correspond to the peak at 1445 cm -1 displayed in the MSN FTIR spectra, indicating the particle presence in the films. Greater analysis of the these SMPs and the characteristic FTIR peaks are discussed elsewhere [5,10,11,15,16,24]. Importantly, use of antioxidants in the particles did not significantly alter the spectroscopic signal from the SMPs, indicating that the antioxidants may be accumulated within the pores rather than on the particle surface and is therefore not interacting significantly with the material matrix during polyurethane synthesis.…”

“…Antioxidants BHT and Piper were substituted, stoichiometrically, for TEA for the alcohol group concentration during synthesis of degradation-resistant, antioxidant-loaded MSNs; TEA was used for producing plain MSNs. 10 In short, a stock solution of DI H 2 O (64 mL), 10.5 mL EtOH, and 25% wt CTAB was mixed together for 20 min at room temperature. TEA (16.5 mL) was added dropwise and stirred until dissolved.…”

“…The products produced over the life of the SMP have been indicated to be cytocompatible at the levels released during mass loss, and more importantly, work by Oliva et al suggests that similar aldehyde functional groups could improve biomaterial-tissue adhesion, and thus this degradation may be fortuitous over the long-term, despite it being reliant upon the cellular response to the material [5,7,8]. In general however, controlling the degradation of SMPs, either by increasing the degradation rate or increasing biostability, would broaden potential medical applications [9][10][11].…”

Improved oxidative biostability of porous shape memory polymers by substituting triethanolamine for glycerol

“…The external stimulus that drives the shape change originally is also used to return the SMP to its original configuration; for several polymer species, including polyurethanes, water and other hydrogen bonding molecules may induce a solvent shape memory effect through interruption of the fixed shape by plasticizing the polymer at lower temperatures . Thermoplastic systems typically display higher recovery forces with lower recoverable strains, while thermoset SMPs have the opposite trend, and with sufficient strain recovery are ideal for void space occluding applications, such as in aneurysm treatment devices in clinical settings …”