Multiscale approach to the morphology, structure, and segmental dynamics of complex degradable aliphatic polyurethanes

Abstract

A multiscale approach spanning from the segmental (subnanometer) up to micrometer level was applied for detailed study of the self‐assembly of aliphatic block polyurethane (PU) elastomers. To understand the principles of the self‐organization of hard and soft segments in the complex multi‐component systems, several two‐component model PU samples, that is, the products of 1,6‐diisocyanatohexane (HDI) with three diols differing in the length and constitution were also prepared, characterized, and investigated: (i) polycarbonate‐based macrodiol (MD), (ii) biodegradable oligomeric diol (DL‐L; product of butane‐1,4‐diol and D,L‐lactide), and (iii) butane‐1,4‐diol (BD). The study (particularly 13C‐1H PILGRIM NMR spectra) reveals complex internal organization and interesting (application appealing) behavior of multi‐component PUs. Hard segments (HDI+BD products) feature self‐assembled and significantly folded chain conformations with interdomain spacing 15–22 nm (small‐angle X‐ray scattering analysis). The small domains are hierarchically assembled in various structural formations of µm size (spherulites) depending on PU composition, as detected by transmission electron microscopy and atomic force microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41590.

Thermal and mechanical properties of multiple‐component aliphatic degradable polyurethanes

“…The popularity of PU elastomers actually derives from the fact that their functional properties can be easily tuned by the choice of reaction components, preparation and processing conditions. The variability of the composition of macrodiols: difference in length and mainly in the constitution (based on polyether, polyester, polycarbonate, polybutadiene and their combinations); chemical nature of diisocyanates (aromatic, aliphatic or cycloaliphatic), and a wide choice of chain extenders (mainly short diols, as butane‐1,4‐diol), together with the possibility to modify the preparation procedure offer an almost infinite variety in end‐use (often unique) properties.…”

“…As the differences detected by above‐mentioned experimental techniques on the macroscopic‐scale have the origin in the behavior at the nanometer level, the analysis and interpretation of their results should be supported by methods that aim at microscopic details, such as spectroscopy (Fourier transform infrared [FTIR], NMR) and microscopy (SEM, AFM, TEM) techniques . Only the appropriate combination of methods of both types helps to elucidate the structure–functional property relationships in details.…”

“…Only the appropriate combination of methods of both types helps to elucidate the structure–functional property relationships in details. As concerns this paper, the discussion and interpretation of macroscopic PUE properties on large scales are based not only on pieces of information gained in this study, but also on the knowledge obtained by the multidisciplinary approach employed in our preceding study …”

“…Polycarbonate‐based macrodiol of M w ca 2800 was used as the component satisfying good tensile characteristics (elongation at break, tensile strength, toughness), while the role of oligomeric diol based on D,L ‐lactide (marked as DL‐L; synthesized for this purpose) was to secure regular distribution of degradable (ester) units in the PU chain. Butane‐1,4‐diol belongs to common chain extenders and 1,6‐diisocyanatohexane is more and more used diisocyanate, especially in coating and film formulations . The differences in PU composition were achieved by varying molar ratio of hydroxyl groups in individual diols; the isocyanate‐to‐total hydroxyl ratio was kept constant and equal to 1.05.…”

“…The differences in PU composition were achieved by varying molar ratio of hydroxyl groups in individual diols; the isocyanate‐to‐total hydroxyl ratio was kept constant and equal to 1.05. The detailed description of our multiscale approach (ranging from the segmental to micrometer levels) used for studying the complex structure, morphology, and segmental dynamic of complex PU elastomers by a combination of spectroscopy, microscopy, and scattering techniques has been published elsewhere . In contrast to the previous study at the nanometer level, this contribution is aimed mainly on mechanical, thermal, and thermomechanical properties of bulk multicomponent PUs (and on comparison with model two‐ and three‐component PUs).…”