Semicrystalline Non-Isocyanate Polyhydroxyurethanes as Thermoplastics and Thermoplastic Elastomers and Their Use in 3D Printing by Fused Filament Fabrication

Abstract

Chemical fixation of the greenhouse gas carbon dioxide with diepoxides followed by melt-phase polyaddition of the resulting difunctional cyclic carbonates with 1,12diaminododecane (DDA) yields semicrystalline polyhydroxurethane (PHU) thermoplastics. Also, 100% biobased semicrystalline PHU thermoplastics are feasible. Opposite to conventional polyurethane syntheses, neither isocyanates nor phosgene are required as intermediates. Preferably, melt-phase polyaddition is performed in a twin-screw compounder in the absence of catalysts, which also catalyze side-reactions. Calorimetric measurements and small-angle X-ray scattering reveal the fundamental structure−property relationships governing PHU crystallization. The PHU melting temperatures vary between 40 and 115 °C, and PHU Young's moduli range from 220 to 1430 MPa. Moreover, non-isocyanate PHU thermoplastic elastomers (TPHE) are readily tailored via melt-phase polyaddition of diamine-terminated flexible PHU prepolymers serving as soft segments combined with semicrystalline PHU as hard segments. As verified by means of thermal analysis (DSC), dynamic mechanical analysis (DMA), X-ray diffraction (SAXS), and microscopy (AFM), the careful balance between soft and semicrystalline hard-segment incorporation accounts for nanophaseseparation, which in the past has failed as a result of phase intermixing resulting from strong hydrogen bonding between soft and hard segments. For the first time, tailored PHU thermoplastics are employed in extrusion-based additive manufacturing by means of fused deposition modeling (FDM) or fused filament fabrication (FFF). Clearly, the presence of hydroxyl groups and their hydrogen bonding improves filament fusion and adhesion essential for achieving mechanical properties similar to PHU melt extrusion without encountering warpage.

Benefit of the Reactive Extrusion in the Course of Polyhydroxyurethanes Synthesis by Aminolysis of Cyclic Carbonates

“…More recently, the authors reported the polymerization of different bis-cyclic carbonates through reactive extrusion process, with 1.12 diaminododecane as a co-monomer, to design semi-crystalline PHUs, suitable for 3D-printing applications. 35 In this study, a series of bio-based biscyclic carbonates, i.e. one ether-activated namely DGDC (Diglycerol Dicarbonate) for which the synthesis and the use for PHUs synthesis has been already described [36][37][38][39] , a second ester-activated, Seb-bCC-ester,(bis((2-oxo-1,3-dioxolan-4-yl)methyl) decanedioate), obtained from Glycerol Carbonate, and a third, non-activated and containing amide linkages, Und-6DA-bisCC, were reacted with the commercial diamines, 1.4-diaminobutane (4DA), 1.6diaminohexane (6DA), 1.10-diaminodecane (10DA), 1.12-diaminododecane (12DA), m-Xylylenediamine (xy-DA), and L-Lysine, by reactive extrusion.…”

Solubility-governed architectural design of polyhydroxyurethane-graft-poly(ε-caprolactone) copolymers

“…1 The most common synthesis route to create PHUs is step-growth polymerization between diamines and cyclic dicarbonates, a highly attractive method from a sustainability point of view. It is atom-economical, it can be performed under bulk conditions and can be combined with extrusion techniques 2,3 to shorten the polymerization time needed and improve the final characteristics of the PHUs.…”

Hybrid polyhydroxyurethanes: How to overcome limitations and reach cutting edge properties?

“…Furthermore, to avoid the use of organic solvents, current trends propose to work in bulk (without solvent), [79] in water [80][81][82][83] or under reactive extrusion or blending. [84][85][86][87] Besides, new routes have also emerged to avoid side-reactions, low conversions, low molar masses and the need of high temperature. For this purpose but also to obtain better properties, the use of different reactive sites is required.…”