羰基合成与选择氧化国家重点实验室（OSSO）知识库

Polyoxymethylene dimethyl ethers (H₃CO(CH₂O)_nCH₃, PODE_n, DMM_n, n≥2) with unique physical and chemical properties open a new route for energy conservation and emission reduction of diesel fuels and can also be used in various industrial fields. The present work firstly prepared a series of high purity single component compound of PODE_n with increasing the number of repeating units (n) from 2 to 5. The structures of the samples were characterized by NMR, IR, Raman and DFT. The mass density and viscosity of PODE_n were measured in the range of 298.15 to 323.15 K. The densities and viscosities gradually decreased with the increase of temperature. While the density and viscosity values gradually enlarged with the number of –CH₂O– units from 2 to 5. The flash point and pour point of PODE_n (n = 2 to 5) were also measured, they all increased with the chain length. The DSC of samples were texted, the absorbed latent heat and released latent heat increased with the degree of polymerization increasing.