Design And Synthesis Of Functional Polyesters

A series of functional groups of aliphatic polyesters were synthesized through molecular design.Firstly,hydroxyl functionalized polylactide（PLA-OH）and hydroxyl functionalized polycaprolactone（PCL-OH）were synthesized by melting polymerization.N₁,N₂-bis（tert-butoxycarbonyl）-L-lysine was utilized to add protecting group,after deprotection with trifluoroacetic acid,amino functionalized polylactide（PLA-NH₂）and amino functionalized polycaprolactone（PCL-NH₂）were prepared.Finally,lovastatin polycaprolactone（LOV-PCL）microspheres were prepared by PCL-OH and lovastatin.The structures and properties of these products were characterized by infrared absorption spectra（FT-IR）,hydrogen nuclear magnetic resonance（¹H-NMR）,differential scanning calorimetry（DSC）,thermal gravimetric analyzer（TGA）,et al.FT-IR and ¹H NMR indicated that a series of different groups polyesters were synthesized successfully.The results show that PLA-OH has the highest yield with reaction temperature of 120℃,reaction time of 4h,the amount of the acid is 4%of the monomer mass.PCL-OH has the highest yield with reaction temperature of 140℃,reaction time of 4h,the amount of the acid is 8%of the monomer mass.Thermal analysis results show that:the glass transition temperature（T_g）,melting point（T_m）and decomposition temperature（T_d）of PLA-OH decreased with increasing molecular weight.For different groups of PLA,when the molecular weight is the same,the T_g is PLA-Boc>PLA-NH₂>PLA-OH ranking from high to low,while T_d is in the order of PLA-OH>PLA-Boc>PLA-NH₂,and T_d of all PLA is more than 200℃.The result indicates that the functional synthesis of PLA have good thermal stability.For the same groups PLA,the greater the molecular weight,the higher T_g,T_m and T_d.The T_g,T_m and T_dof PCL-OH decreased with increasing molecular weight.For different groups of PCL,when the molecular weight is same,the T_g is PCL-Boc>PCL-NH₂>PCL-OH from high to low,while T_d is PCL-OH>PCL-Boc>PCL-NH₂,and the T_d of all PCL is more than200°C.The result indicates that the functional synthesis of PCL have good thermal stability.For the same groups PCL,the greater the molecular weight,the higher T_g,T_m and T_d.SEM,DSC and UV Vis spectra show that,LOV-PCL microspheres were synthesized,the higher the molecular weight of PCL-OH,the more drug loading.In summary,functionalized polylactide and functionalized polycaprolactone were synthesized successfully,the polycaprolactone microspheres of lovastatin were prepared.The article provide a new technology for the preparation of drug microspheres.