Waterborne polyurethanes from CO₂ based polyols with comprehensive hydrolysis/oxidation resistance

Abstract

5Carbon dioxide based oligo(carbonate-ether) diol (CO 2 -polyol) with both carbonate units and ether units in one polymer chain were prepared from copolymerization of CO 2 and propylene oxide (PO) using zinccobalt double metal complex as catalyst, and used to prepare CO 2 based waterborne polyurethane (CO 2 -WPU). The carbonate units in CO 2 -polyol improved the mechanical and oxidation resistance properties of CO 2 -WPU, while the ether units in CO 2 -polyol enhanced the hydrolysis resistance of CO 2 -WPU. The 10 tensile strength of CO 2 -WPU didn't show obvious drop during immersion in 0.25% sodium hydroxide solution, whereas that of oligoesterol based WPU dropped over 50% after 300 min, and lost mechanical property after 520 min immersion. Meanwhile, the retention of tensile strength of CO 2 -WPU was Ca.72% even after 46 h immersion in 6 wt% H 2 O 2 solution, while that was only Ca.32% for oligoetherol based WPU. Moreover, the thermal-mechanical performance of CO 2 -WPU film can be conveniently adjusted by 15 carbonate unit content (CU%) in CO 2 -polyol, i.e., when CU% in CO 2 -polyol increased from 30% to 66%, the glass transition temperature (T g ) increased from -7.8 0 C to 18.8 0 C, accompanied by an increase of tensile strength from 35.6 MPa to 52.2 MPa, a decrease of elongation at break from 630% to 410%. This work suggests that the CO 2 -WPU may be promising alternative for conventional WPU whose oligoetherol and oligoesterol were from fossil resources, and its comprehensive hydrolysis/oxidation 20 resistance may be a bonus unavailable from common oligomerol based WPU. 65 75%. 13 Recently, there is a nice report from Bardow that CO 2polyol may be viable alternative in polyurethane industry from an environmental point of view based on life cycle assessment. 14 We are wondering whether polyol derived from CO 2 and PO is suitable oligomerol for WPU. Up to now, however, there is few 70 reports on such issue.

CO2-fixation into cyclic and polymeric carbonates: principles and applications

“…341 The advantages of CO 2 -based poly(carbonateether)s as polyols for polyurethane synthesis over their polyester and polyether counterparts was further demonstrated by synthesising a series of polyurethanes from poly( propylene carbonate-ether) polyols and comparing them with polyurethanes incorporating polyester ( poly(butylene adipate glycol)) or polyether ( poly( propylene oxide glycol)) segments. 326 It was observed that the polycarbonate-based polyurethane (with 66% carbonate linkages and 34% ether linkages) exhibited better mechanical properties, although with a lower elongation at break compared to the other two polyurethanes, indicating a more rigid plastic behaviour (Table 10, entries 9-11). In addition, the poly(carbonate-ether)-based polyurethane exhibited better resistance against hydrolysis and oxidation compared to the polyester and polyether polyurethanes, which was ascribed to the presence of ether linkages with good hydrolysis resistance and to the relatively hydrophobic and rigid propylene carbonate repeating units, which might limit the permeation of water and, thus, increase the hydrolysis and oxidation resistance.…”

“…336 A general drawback of polyurethane formulations for foams is that products prepared with polyesters as polyols exhibit excellent mechanical properties but poor hydrolysis resistance, while polyurethanes prepared using polyethers as polyols possess proper hydrolysis resistance but insufficient oxidation resistance and display poor mechanical properties. 326,327 Since CO 2 -epoxide-based polycarbonates share similarities with both polyesters and polyethers with regard to the chemical structure but have lower tendency to hydrolyse compared to polyesters, polycarbonate polyols have been investigated as an alternative to conventional polyester and polyether polyols. Additionally, employing CO 2 -based poly(carbonate-ether) polyols is a greener option, as it allows increasing the renewable content of the polymer (up to 43 wt% CO 2 in the case of poly( propylene carbonate)).…”

Recyclable bio‐based crosslinked polyurethanes with self‐healing ability

“…PU is usually prepared by the step‐growth polymerization of isocyanates with two or more NCO groups with petroleum‐based polyols . Due to the rapid consumption of fossil resources and serious environmental pollution, intensive interest has been paid to developing bio‐based polyols from renewable resources for preparing PU . The most popular renewable polyols are currently derived from plant oil .…”

Facile Room-Temperature Preparation of Flexible Polyurethane Foams from Carbon Dioxide Based Poly(ether carbonate) Polyols with a Reduced Generation of Acetaldehyde

“…18 In addition, the PEC polyols exhibit better hydrolysis resistance and oxidative stability compared with polyester- and polyether-type polyols. 19 Chemical and oxidative stability derived from PEC polyols are important and highly desirable properties in PU applications. Therefore, the PEC polyols represent substitutable and sustainable polyols, which exemplify the chemical conversion of renewable CO 2 into valuable products.…”