Molecular Brushes with a Polyimide Backbone and Poly(ε-Caprolactone) Side Chains by the Combination of ATRP, ROP, and CuAAC

Abstract

An approach to the synthesis of the novel molecular brushes with a polyimide (PI) backbone and poly(ε-caprolactone) (PCL) side chains was developed. To obtain such copolymers, a combination of various synthesis methods was used, including polycondensation, atom transfer radical polymerization (ATRP), ring opening polymerization (ROP), and Cu (I)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAC). ATRP of 2-hydroxyethyl methacrylate (HEMA) on PI macroinitiator followed by ROP of ε-caprolactone (CL) provided a “brush on brush” structure PI-g-(PHEMA-g-PCL). For the synthesis of PI-g-PCL two synthetic routes combining ROP and CuAAC were compared: (1) polymer-analogous transformations of a multicenter PI macroinitiator with an initiating hydroxyl group separated from the main chain by a triazole ring followed by ROP of CL, or (2) a separate synthesis of macromonomers with the desirable functional groups (polyimide with azide groups and PCL with terminal alkyne groups), followed by a click reaction. Results showed that the first approach allows to obtain graft copolymers with a PI backbone and relatively short PCL side chains. While the implementation of the second approach leads to a more significant increase in the molecular weight, but unreacted linear PCL remains in the system. Obtained macroinitiators and copolymers were characterized using 1H NMR and IR spectroscopy, their molecular weight characteristics were determined by SEC with triple detection. TGA and DSC were used to determine their thermal properties. X-ray scattering data showed that the introduction of a polyimide block into the polycaprolactone matrix did not change the degree of crystallinity of PCL.

Advances in design of polymer brush functionalized inorganic nanomaterials and their applications in biomedical arena

“…Numerous external factors like solvent quality (Aoki et al, 2008;Lenz et al, 2011), pH (Lego et al, 2010), ionic strength, and the presence of various electrolytes (Bünsow et al, 2010;Tan et al, 2011aTan et al, , 2011b or small molecules (Bracha & Bar-Ziv, 2014) influence brush configuration and contribute to responsive brushes with tunable functionalities like particle agglomeration (Nagase et al, 2012;Zan et al, 2019), lubrication, and protein adsorption (Laktionov et al, 2021). Polymer brushes can also produce block copolymer architectures (Kashina et al, 2021;Poisson et al, 2021;Smenda et al, 2021) and mixed polymer brushes (Bo et al, 2021;Bohannon et al, 2021;Ihara et al, 2021) that can be easily engineered to demonstrate stimuli-responsive characteristics.…”