Preparation Of Functionalized Poly (Ether Carbonate) And Cyclic Carbonate And Their Application In Waterborne Polyurethane

The effective conversion of CO2 into general polymer materials is a research hotspot in the field of CO2 utilization.The copolymerization reaction of epoxide and CO2 can obtain poly(ether-carbonate)(PEC)which contains both polyester segments and polyether segments.However,there was still little research on the preparation of PEC-based WPU.Functionalized PEC-based WPU were even less reported.Besides,the cyclization reaction of epoxide and CO2 can generate cyclic carbonate.The further reaction of cyclic carbonate with amine can produce non-isocyanate polyurethane(NIPU),which can reduce the dependence of the polyurethane industry on highly toxic and highly polluting isocyanates.In this work,we designed and prepared several functional poly(ether-carbonate)s.Then we used PEC as the soft segment of WPU to improve the thermal stability,water resistance and mechanical properties.We also prepared bio-based non-isocyanate waterborne polyurethane coatings synthesized from cyclic carbonates.The main research contents and results of this dissertation are as follows:(1)Siloxane-functionalized poly(ether-carbonate)(SPEC)was prepared by copolymerization of ?-(2,3-epoxypropoxy)propytrimethoxysilane(KH-5 60),propylene oxide(PO)and CO2,using polypropylene glycol-400(PPG-400)as the initiator agent and double metal cyanide complex(DMC)as the catalyst.SPEC has a Mn of 1500-3900 g/mol,a PDI of 1.7-2.5,a carbonate segment ratio of 9.2-21.9 mol%,and a siloxane segment ratio of 3.6-11.1 mol%.With SPEC as the soft segment and isophorone diisocyanate(IPDI)as the hard segment,stable emulsion of siloxane-functionalized waterborne polyurethane SPEC-WPU was prepared.SPEC-WPU has hydrolyzable siloxane segments,which can form a WPU cross-linked network.SPEC-WPU exhibits better mechanical properties and water resistance than PEC-WPU and PPG-WPU prepared from PEC and PPG with the same molecular weight.The SPEC-WPU had a tensile strength of 16.5 MPa,an elongation at break of 683.4%,a Td,s%of 227 ?,a surface water contact angle of 82°,and a water absorption rate of 36.6%at 90 h.The results show that SPEC from the silane coupling agent and CO2 is expected to be a substitute for common commercial polyols.(2)High-content siloxane-functionalized poly(ether-carbonate)HSPEC was prepared by copolymerization of KH-560 and CO2,using PPG-400 as the initiator agent and DMC as the catalyst.HSPEC has a Mn of 800-2300 g/mol,a PDI of 1.2-2.3,a carbonate segment ratio of 15-30 mol%,and a siloxane segment ratio of 14-60 mol%.With HSPEC/PPG-2000 as the soft segment,IPDI as the hard segment,a stable emulsion of high-content siloxane-functionalized waterborne polyurethane HSPEC-WPU was prepared.The emulsion particle size of HSPEC-WPU was less than 200 nm.The siloxane segments of HSPEC could be cross-linked during the emulsification stage,effectively improving the tensile strength and Young's modulus of WPU.The WPU with 15 wt%HSPEC has the highest tensile strength and Young's modulus,which were 15.9 MPa and 137.0 MPa,respectively.Compared with WPU without HSPEC,it was increased by 55.9%and 161.9%,respectively.With the increased dosage of HSPEC,the thermal stability of WPU slightly improved.Td,5%of WPU was about 237.8-246.5?,and the thermal decomposition rate curve in the first decomposition step moves toward the high-temperature region.When the dosage of HSPEC was greater than 20%,the performance of WPU showed a decline.(3)Eugenol-based poly(ether-carbonate)EUPEC was prepared by the copolymerization reaction of eugenol epoxy resin,PO and CO2 by using PPG-400 as the initiator agent,DMC as the catalyst.The EUPEC has a Mn of 3700-4400 g/mol,a PDI of 1.8-2.3,a carbonate segment ration of 18-39 mol%,and a eugenol segment ratio of 2.1-11.2 mol%.Moreover,using different EUPEC/PPG-2000 according to formula 1(mass ratio 10:90)and formula 2(mass ratio 20:80)as soft segments,bio-based waterborne polyurethane EUWPU was prepared.We also set the control group by using PPG-4000/PPG-2000 as the soft segment according to the same formula.The particle size of the modified WPU emulsion was between 95-110 nm,and the dried EUWPU films had a Tg of-57.0? to-53.5?,an initial decomposition temperature of higher than 240?,a tensile strength of 7.7-14.7 MPa,and an elongation at break of 538-623%.Compared with the control group without EUPEC,tensile strength and Young's modulus of EUWPU in Formula 1 were increased by 87.9%and 43.3%,respectively;and tensile strength and Young's modulus of EUWPU in Formula 2 were increased by 133%and 198%,respectively.The results showed that the high-rigidity long-chain polyol could improve the tensile strength and Young's modulus while maintaining its elongation at break,which provided an idea for the preparation of high-strength and high-toughness waterborne polyurethane.(4)Diphenolic acid(DPA),a bio-based material with a similar structure to bisphenol A,was reacted with CO2 to prepare DPA-based bis(cyclic carbonate),followed by ring-opening reaction with different primary diamines to prepare various DPA-based poly(hydroxyl urethane)(PHU).By using acetone as the solvent and bisphenol A epoxy resin as the cross-linking agent,a hybrid solvent-borne PHU coating film was prepared.The coating has an excellent hardness(4H),adhesion(grade 1),and a very flat surface(Rm less than 5 nm),and the water contact angle was 82°-108°.Subsequently,by the reaction bewteen succinic anhydride and hydroxyl groups on PHU and neutralizing with sodium bicarbonate(NaHCO3),waterborne PHU was successfully prepared.By adjusting the dosage of sodium bicarbonate(NaHCO3),the particle size of the PHU emulsion was controlled between 78-321 nm.Using water-based bisphenol A epoxy resin as a cross-linking agent,a hybrid waterborne PHU coating film was prepared.The adhesion of waterborne PHU film was between grade 4 and grade 1,and the pencil hardness was between 3B and 3H.The AFM image shows the surface morphology of the water-based PHU coating,which shows a larger surface roughness when the NaHCO3 addition is too low and too high,indicating that there is an optimal range of NaHCO3 addition(12.5%-16.7%).The maximum roughness of the optimized water-based PHU coating is only 2.4 nm,which could achieve the flatness of the solvent-borne PHU coating.