Tuning the Properties of Biobased PU Coatings via Selective Lignin Fractionation and Partial Depolymerization

Polyurethane (PU) coatings with high lignin content and tunable properties were made using a combination of fractionation and partial catalytic depolymerization as a novel strategy to tailor lignin molar mass and hydroxyl group reactivity, the key parameters for use in PU coatings. Acetone organosolv lignin obtained from pilot-scale fractionation of beech wood chips was processed at the kilogram scale to produce lignin fractions with specific molar mass ranges (Mw 1000-6000 g/mol) and reduced polydispersity. Aliphatic hydroxyl groups were distributed relatively evenly over the lignin fractions, allowing detailed study of the correlation between lignin molar mass and hydroxyl group reactivity using an aliphatic polyisocyanate linker. As expected, the high molar mass fractions exhibited low cross-linking reactivity, yielding rigid coatings with a high glass transition temperature (Tg). The lower Mw fractions showed increased lignin reactivity, extent of cross-linking, and gave coatings with enhanced flexibility and lower Tg. Lignin properties could be further tailored by lignin partial depolymerization by reduction (PDR) of the beech wood lignin and its high molar mass fractions; excellent translation of the PDR process was observed from laboratory to the pilot scale necessary for coating applications in prospective industrial scenarios. Lignin depolymerization significantly improved lignin reactivity, and coatings produced from PDR lignin showed the lowest Tg values and highest coating flexibility. Overall, this study provides a powerful strategy for the production of PU coatings with tailored properties and high (>90%) biomass content, paving the path to the development of fully green and circular PU materials

Tuning the Properties of Biobased PU Coatings via Selective Lignin Fractionation and Partial Depolymerization

Polyurethane (PU) coatings with high lignin content and tunable properties were made using a combination of fractionation and partial catalytic depolymerization as a novel strategy to tailor lignin molar mass and hydroxyl group reactivity, the key parameters for use in PU coatings. Acetone organosolv lignin obtained from pilot-scale fractionation of beech wood chips was processed at the kilogram scale to produce lignin fractions with specific molar mass ranges (Mw 1000-6000 g/mol) and reduced polydispersity. Aliphatic hydroxyl groups were distributed relatively evenly over the lignin fractions, allowing detailed study of the correlation between lignin molar mass and hydroxyl group reactivity using an aliphatic polyisocyanate linker. As expected, the high molar mass fractions exhibited low cross-linking reactivity, yielding rigid coatings with a high glass transition temperature (Tg). The lower Mw fractions showed increased lignin reactivity, extent of cross-linking, and gave coatings with enhanced flexibility and lower Tg. Lignin properties could be further tailored by lignin partial depolymerization by reduction (PDR) of the beech wood lignin and its high molar mass fractions; excellent translation of the PDR process was observed from laboratory to the pilot scale necessary for coating applications in prospective industrial scenarios. Lignin depolymerization significantly improved lignin reactivity, and coatings produced from PDR lignin showed the lowest Tg values and highest coating flexibility. Overall, this study provides a powerful strategy for the production of PU coatings with tailored properties and high (>90%) biomass content, paving the path to the development of fully green and circular PU materials

Efficacy and safety of tenecteplase in combination with enoxaparin, abciximab, or unfractionated heparin: The ASSENT-3 randomised trial in acute myocardial infarction

Background: Current fibrinolytic therapies fail to achieve optimum reperfusion in many patients. Low-molecular-weight heparins and platelet glycoprotein IIb/IIIa inhibitors have shown the potential to improve pharmacological reperfusion therapy. We did a randomised, open-label trial to compare the efficacy and safety of tenecteplase plus enoxaparin or abciximab, with that of tenecteplase plus weight-adjusted unfractionated heparin in patients with acute myocardial infarction. Methods: 6095 patients with acute myocardial infarction of less than 6 h were randomly assigned one of three regimens: full-dose tenecteplase and enoxaparin for a maximum of 7 days (enoxaparin group; n=2040), half-dose tenecteplase with weight-adjusted low-dose unfractionated heparin and a 12-h infusion of abciximab (abciximab group; n=2017), or full-dose tenecteplase with weight-adjusted unfractionated heparin for 48 h (unfractionated heparin group; n=2038). The primary endpoints were the composites of 30-day mortality, in-hospital reinfarction, or in-hospital refractory ischaemia (efficacy endpoint), and the above endpoint plus in-hospital intracranial haemorrhage or in-hospital major bleeding complications (efficacy plus safety endpoint). Analysis was by intention to treat. Findings: There were significantly fewer efficacy endpoints in the enoxaparin and abciximab groups than in the unfractionated heparin group: 233/2037 (11.4%) versus 315/2038 (15.4%; relative risk 0.74 [95% CI 0.63-0.87], p=0.0002) for enoxaparin, and 223/2017 (11.1%) versus 315/2038 (15.4%; 0.72 [0.61-0.84], p<0.0001) for abciximab. The same was true for the efficacy plus safety endpoint: 280/2037 (13.7%) versus 347/2036 (17.0%; 0.81 [0.70-0.93], p=0.0037) for enoxaparin, and 287/2016 (14.2%) versus 347/2036 (17.0%; 0.84 [0.72-0.96], p=0.01416) for abciximab. Interpretation: The tenecteplase plus enoxaparin or abciximab regimens studied here reduce the frequency of ischaemic complications of an acute myocardial infarction. In light of its ease of administration, tenecteplase plus enoxaparin seems to be an attractive alternative reperfusion regimen that warrants further study