Property enhancement of healable supramolecular polyurethanes

Abstract

Low molecular weight additives which can cooperatively self-assemble with supramolecular polyurethanes via complementary hydrogen bonding interactions offer an attractive route to enhancing the properties of addressable polymer networks. Here, we present the design, synthesis, characterisation and mechanical properties of a series of supramolecular polyurethanes with varied loadings of a low molecular weight bis-urea additive. These additives are able to self-assemble with analogous recognition motifs within the supramolecular polyurethanes to form polar 'hard' domains, promoting phase separation within the material and, crucially, increasing the strength of the polymer network. In addition, the bis-urea additive is a by-product within the polymerisation and thus can be synthesised in situ, without the need for complex purification or blending. The mechanical properties of these reinforced polymers were enhanced when compared to the pristine supramolecular polyurethane alone, as a result of higher degrees of order within the polymer matrix. Furthermore, a formulation comprising the small molecule blended with the supramolecular polyurethane was produced to examine the effect of material preparation and filler dispersion within the polymer matrix. Interestingly, the mechanical performance of a blended material was diminished as a result of modest dispersion and incorporation within the polymer matrix. These findings thus demonstrate a facile, one-pot, method that does not require purification to produce reinforced supramolecular polyurethanes. This methodology may find use in industrial applications in which enhancements to the physical and mechanical properties can be easily achieved through the in situ synthesis of low molecular weight additives within the polymerisation.

A 3D printed drug delivery implant formed from a dynamic supramolecular polyurethane formulation

“…Analysis of SPU1 by GPC (Figure S7) revealed a bimodal distribution, attributed to chain extension within the polyurethane, with a Mn of 6100 Da and Đ = 2.06, corresponding to approximately 2 repeat units per polymer chain. 34 This is in close agreement with the integration analysis carried out by 1 H NMR spectroscopy. The thermal characteristics of the polymer were also probed using differential scanning calorimetry (Figure S8) which revealed a Tg at -47.8 °C, which can be attributed to the soft domain of the phase separated supramolecular polymer, comprising of the hydrogenated polybutadiene.…”

“…These results are in good agreement with structurally related SPUs which demonstrate two thermal transitions. 31,32,34 Furthermore, the temperature range of Tgs of the bulk and self-assembled components indicated that the polymer was relatively malleable at room temperature and appropriate for use as a biomedical device produced by hot-melt extrusion printing. In order to assess the suitability of the supramolecular polymer for use in a biomedical device, films were required for analysis prior to 3D printing.…”

“…Herein, a dynamic supramolecular polyurethane (SPU) is reported which is able to self-assemble through hydrogen bonding and π-π stacking interactions, 31 giving rise to thermally reversable material properties. [32][33][34] The thermally addressable nature of the SPU makes it an ideal candidate for hot-melt extrusion, inclusive of 3D printing approaches, as the melt viscosity is in a suitable range for printing and a stiff, yet flexible structure is rapidly produced upon cooling. 35 The relatively low temperature required to dissociate the supramolecular interactions, and thus deposit the material, may also widen the range of actives available to be formulated as a result of the mild processing conditions preventing thermal degradation.…”

The effect of chiral end groups on the assembly of supramolecular polyurethanes

“…The increase in final dissociation temperature was attributed to more ordered assembly in the homochiral terminated polymer 1. Additionally, the extent of hydrogen bonding of urea and urethane groups remained greater in the homochiral polymer network 1 when compared with previously reported [63][64][65][66][67] SPUs featuring similar end-groups, remaining stable even at 150°C, indicating a more stable assembly formed in 1 through the enhanced order in the packing of the hard domain. After thermal equilibration of the SPU 1 film for approximately 30 minutes at room temperature, full recovery of the relative percentage of hydrogen bonding was observed within the SPUs.…”

Marble Powder Blended Utilization Polyurethane as Soundproof Materials

“…Solid polyurethane foam is one of the most efficient, high-performance insulating materials, allowing for very good energy savings in adjusting space usage. Excellent insulation of buildings is a significant contributor [8].…”