Enhanced shape memory performance of polyurethanes via the incorporation of organic or inorganic networks

Abstract

A diol compound with a reactive azetidine-2,4-dione group was prepared and introduced as a side chain moiety of poly(3-caprolactone) (PCL) based polyurethane (PU). The PUs with reactive pendants were crosslinked by 1,6-diaminohexane, or modified by an alkoxysilane (3-aminopropyltriethoxysilane, APTS) followed by a sol-gel reaction to bring about crosslinked PUs for shape memory applications. Thermal and mechanical properties of the crosslinked PUs are strongly dependent on the chemical structure of the interchain-linker between the polymer chains. Higher tensile strengths would be achieved for the PU samples crosslinked with alkoxysilanes in comparison with the ones crosslinked with an aliphatic diamine, while higher values of elongation at break were observed for the latter. As compared to the PCL based linear and side-chain PUs, much better shape memory performance was observed as the PU sample was crosslinked with the aliphatic diamine, or by the sol-gel reaction of alkoxysilanes, particularly the latter. Higher shape retention (91%) and recovery (99%) ratios were observed for the CPU samples with inorganic networks. By introducing the chemically crosslinked structures, the deformed PU samples completely recovered their original shape in less than 10 seconds without any deficiency during shape recovery measurements.Scheme 1 Synthesis route of 4-isocyanate-4 0 -(3,3-dimethyl-2,4-dioxo-azetidine)diphenyl methane based diol (IDD-diol).Scheme 2 Synthesis routes of MDI and PCL based LPUs and SPUs.This journal is Fig. 4 X-ray diffraction patterns of (a) LPUs (LPU45, LPU50, and LPU55) and SPUs (SPU45, SPU50, and SPU55), and (b) CPUs (CPU55-A05, CPU55-A10, CPU55-S20, CPU55-S40, and CPU55-S60).This journal is

Influence of the soft segment nature on the thermomechanical behavior of shape memory polyurethanes

“…). ATR‐FTIR was used to assess the formation of polyurethanes . Chemical structure of the resultant SMPUs was fully confirmed and results were reported in a previous work .…”

A Facile Synthetic Route to Ether Diols Derived from 1,1-Cyclopentylenylbisphenol for Robust Cardo-Type Polyurethanes

“…To develop shape memory materials, a polymer exhibits both a large modulus difference during transition range and a lengthy rubbery plateau. − For segmented polyurethanes, the shape deformation can be realized via the reversible phase transition such as glass transition from the soft segment, while the shape recovery could be bound via strong hydrogen-bonding interactions from the hard segment . It is noted that the presence of strong hydrogen bonding from the urethane linkages can achieve sufficient physical cross-linking to exhibit elastomeric properties, without resorting to either chemical cross-linking or crystallinity for linear segmented PUs .…”

“…By incorporation of cardo five-membered ring structures into the PUs (Scheme S1), we have found that the resulting polymers were imparted with certain distinctive mechanical and morphological properties as compared to those of the PUs based on common bisphenols. These cardo-type PUs exhibited a large modulus variation at glass transition, and an extended rubbery plateau in dynamic mechanical analyses, which might be fit for shape memory materials. − …”

Design of Thermoplastic Polyurethanes with Conferred Antibacterial, Mechanical, and Cytotoxic Properties for Catheter Application

“…This can be explained with the greater macromolecular chain mobility toward a greater degree of order after the addition of the active moieties, as part of the hard segment. 27 Thermal transitions relative to the materials soft segment melting temperature (T m ) can be observed in the range of 156 to 170 °C, explained with the high hard segment content. 28 The decrease in T m values, from 189 °C for TPUr to 145 °C for TPU-QPS-TOP, was explained with the addition of the ionic moieties, reflecting again the greater polymer chains mobility and less thermally stable crystalline domains (Figure 5).…”