One-Pot Nonisocyanate Synthesis of Sequence-Controlled Poly(hydroxy urethane)s from a Bis(six-membered cyclic carbonate) and Two Different Diamines

Boosting the Reactivity of Bis-Lactones to Enable Step-Growth Polymerization at Room Temperature

The development of new sustainable polymeric materials endowed with improved performances but minimal environmental impact is a major concern, with polyesters as primary targets. Lactones are key monomers thanks to ring-opening polymerization, but their use in step-growth polymerization has remained scarce and challenging. Herein, we report a powerful bis(γ-lactone) (γSL) that was efficiently prepared on a gram scale from malonic acid by Pd-catalyzed cycloisomerization. The γ-exomethylene moieties and the spiro structure greatly enhance its reactivity toward ring-opening and enable step-growth polymerization under mild conditions. Using diols, dithiols, or diamines as comonomers, a variety of regioregular (AB)n copolymers with diverse linkages and functional groups (from oxo-ester to β-thioether lactone and β-hydroxy-lactame) have been readily prepared. Reaction modeling and monitoring revealed the occurrence of an original trans-lactonization process following the first ring-opening of γSL. This peculiar reactivity opens the way to regioregular (ABAC)n terpolymers, as illustrated by the successive step-growth polymerization of γSL with a diol and a diamine.

Biodegradable isocyanate-free polyurethane films via a noncatalytic route: facile modified polycaprolactone triol and biobased diamine as precursors

A facile synthesis of isocyanate free polyurethanes (PU) was executed by the reaction of biodegradable cyclic carbonate and sustainable diamines generated via chemical modification. The biodegradable polyol polycaprolactone triol (PCL) was transformed into a new glycerol carbonate derivative, PCL-(COOGC)₃, and subjected to polyaddition with the diamines linalool diamine (LLDA), isosorbide diamine (ISODA) and hexamethylene diamine (HDA). Polyaddition of PCL-(COOGC)₃ with the above diamine precursors was conducted via a one-pot reaction under catalyst-free reaction conditions prior to film casting. The above precursors were characterized by Fourier-transform infrared (FTIR) and ¹H and ¹³C nuclear magnetic resonance spectroscopies, high-resolution mass spectrometry and electrospray ionization matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, whereas the PU films were studied by attenuated total reflectance-FTIR spectroscopy, solid state ¹³C NMR, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, X-ray diffractometry, differential scanning calorimetry and thermogravimetric analysis. High onset degradation temperature (T _d) values were observed for the PU films PU-1 (345.8 °C), PU-2 (309.6 °C) and PU-3 (344.6 °C), and further studies, including cross-link density, water contact angle, swelling behaviour and biodegradation (phosphate-buffered saline medium, pH = 7.2 at 45 °C) measurements, were conducted.