Block Copolymers of Methoxypoly(Ethylene Oxide) and Poly(ϵ-Caprolactone): Synthesis, Structure, Micellization, and Interaction with Prednisolon

Abstract

A series of MOPEO-b-PCL diblock copolymers (DBCs) with M _nMOPEO = 2.5 · 10³ and M _nPCL = (0.28 ÷ 2.43) · 10⁴ was synthesized using the anionic ring-opening block copolymerization. A bulk structure of the copolymers was studied with DSC. One glass transition and three melting peaks for MOPEO-b-PCL were found, thus implying the existence of separate crystalline domains of both blocks in a copolymer structure. The intense micellization of DBCs in dioxane/aqueous solutions was found with a spectrophotometry, a static light scattering, and photography. A reduction in CMC and an increase in −ΔG° values with growth of the PCL length and at the addition of prednisolon (PS) were established. The hydrogen bonding of PS with DBCs was confirmed with FTIR spectroscopy.

Keywords:

• Diblock copolymer
• drug
• micellization
• nanocontainer
• structure

Notes

¹The weight fraction of MOPEO in the diblock copolymer.

²The ratio between units in PCL and MOPEO blocks, base-mol_PCL/base-mol_MOPEO.

¹The glass transition temperature.

²The temperature region for a certain thermal transition.

³The specific capacity jump.

⁴The melting temperature.

⁵The melting enthalpy.

⁶The crystallinity degree: for pure MOPEG , where is the melting enthalpy for 100% crystalline PEO (196.8 J · g⁻¹) [14], but for MOPEO and PCL blocks in the copolymer [14], where w is the mass fraction of corresponding block in DBC; the value of for 100% crystalline PCL was taken of the study [12].

⁷The crystallinity degree, calculated under condition of a participation of only PCL blocks in this melting process.

¹The molar ratio between PS and DBC ϕ = 0.25 mol_PS/base-mol_DBC was constant in all the blends.