Study On The Copolymerization Of Carbon Dioxide With Epoxy Compounds Catalyzed Under Double Metal Cyanide Complexes

Double metal cyanide complexes?DMC?catalyst is one of the most industrially valuable catalysts,which can efficiently catalyze the oligomerization of epoxides and carbon dioxide to prepare oligo?carbonate-ether?polyols.The preparation process not only makes full use of greenhouse gas CO₂,but also consumes less energy than conventional polyols preparation.The research has demonstrated that oligo?carbonateether?polyols with 20 wt%CO₂ have been estimated to reduce greenhouse gas emissions and energy consumption by about 11–19%and 13–16%,respectively,as compared to polyether polyols analogues in the production process.Meanwhile,the polyurethanes made from oligo?carbonate-ether?polyols have more excellent properties in comparison with the polyethers polyurethane and polyesters polyurethane,such as wear resistance,water resistance,and solvent resistance.Moreover,oligo?carbonate-ether?polyols prepared using bisphenols compounds as chain transfer agents?CTA?can impart excellent flame retardant properties to polyurethanes because of low H/C ratio of bisphenols compounds.In this thesis:we first discussed the the effect of different bisphenols as CTA on the preparation of low molecular weight oligo?carbonateether?polyols by propylene oxide?PO?/CO₂copolymerization.Then we investigated the effect of the reaction conditions on the oligomeric reaction and the properties of oligo?carbonateether?polyols producted with the preferred bisphenol compound 4,4'-biphenyldiphenol?DOD?as the chain transfer agent.The main results were summarized as follows:1.The low molecular weight oligo?carbonateether?polyols was prepared by using bisphenol compounds with different pK_a values as CTAs.The experimental results show that bisphenol compounds with lower pK_a value that the terminal hydroxyl activity is higher on the catalyst a greater impact,which is not conducive to the progress of the reaction.Bisphenol compounds with larger steric hinders reduce their chain transfer capacity due to steric hindrance,with a slight activity.However,while higher pK_a values lone ligand structure will occur and the electrophilic group of the DMC catalyst,a greater influence on the catalyst,the reaction is carried out against.It was found by experiment that the preparation of oligo?carbonateether?polyols with DOD as CTA was the most excellent.2.The preparation of oligo?carbonate-ether?polyols was studied.We systematically investigated the influences of the molar ratio of PO/DOD,reaction temperature,reaction pressure,the amount of catalyst,etc.on oligomerizations under DOD as CTA.As the experimental results show,The number average molecular weight?M_n?of obtained polyols was in the range of 2200g/mol to 4300 g/mol by changing the molar ratio of PO/DOD.Lower temperature and higher CO₂pressure were beneficial for increasing f_PPC while reaction yield,PO conversion and M_n are decrased.We can through the longer reaction time to improve yield and PO conversion.The of f_PPC of polyols reached to 41.7%and by-product cyclic PC is just 8.3 wt%when the oligomerization was performed at 90 ^? under 4.0 MPa with 20 mg DMC for 6 h in 100 mL PO,the molar ratio of PO/DOD is 42.9 mol/mol.And the viscosity of polyols is increased with increasing Mn and fPPC.