Synthetic Route to Conjugated Donor–Acceptor Polymer Brushes via Alternating Copolymerization of Bifunctional Monomers

Abstract

Alternating donor–acceptor conjugated polymers, widely investigated due to their applications in organic photovoltaics, are obtained mainly by cross-coupling reactions. Such a synthetic route exhibits limited efficiency and requires using, for example, toxic palladium catalysts. Furthermore, the coating process demands solubility of the macromolecules, provided by the introduction of alkyl side chains, which have an impact on the properties of the final material. Here, we present the synthetic route to ladder-like donor–acceptor polymer brushes using alternating copolymerization of modified styrene and maleic anhydride monomers, ensuring proper arrangement of the pendant donor and acceptor groups along the polymer chains grafted from a surface. As a proof of concept, macromolecules with pendant thiophene and benzothiadiazole groups were grafted by means of RAFT and metal-free ATRP polymerizations. Densely packed brushes with a thickness up to 200 nm were obtained in a single polymerization process, without the necessity of using metal-based catalysts or bulky substituents of the monomers. Oxidative polymerization using FeCl3 was then applied to form the conjugated chains in a double-stranded (ladder-like) architecture.

Synthesis of alternating copolymer PAspNa‐alt‐PAsp(Pr) for drug delivery system

“…As mentioned, the aminolysis of PBLA is a simple and efficient method to attribute functional fractions to the backbone of PBLA without causing undesirable side reactions. The succinimide was formed in the polymer backbone, which is an intermediate converted to poly‐aspartamide to accompany the α, β isomerization of the backbone is shown to be the mechanism by which this reaction proceeds 19 . It is important to note that the (─CH) peak at 4.6 ppm has shifted significantly when compared to the PBLA spectra in Figure 3 after 10 min.…”

“…The succinimide was formed in the polymer backbone, which is an intermediate converted to poly-aspartamide to accompany the α, β isomerization of the backbone is shown to be the mechanism by which this reaction proceeds. 19 It is important to note that the (─CH) peak at 4.6 ppm has shifted significantly when compared to the PBLA spectra in Figure 3 after 10 min. The new peaks were also clearly seen at 5.3 (k) and 5.1 (m) ppm (Figure 3).…”

“…18 Despite their potential advantages, these alternative copolymers also have limitations in terms of their synthesis and properties, highlighting the need for continued development of new copolymers for drug delivery applications. 19 Poly(β-benzyl-L-aspartate) (PBLA) is a biocompatible polymer that has received considerable attention for drug delivery applications due to its tunable properties and ability to be modified at the side chains. 20,21 PBLA-based drug delivery systems have shown promise in targeted drug delivery and sustained release applications, as well as in the delivery of poorly soluble drugs.…”

“…The alternative copolymer demonstrated a rapid release of DOX within cells and exhibited superior anticancer efficacy compared to free DOX in in vitro cell experiments 18 . Despite their potential advantages, these alternative copolymers also have limitations in terms of their synthesis and properties, highlighting the need for continued development of new copolymers for drug delivery applications 19 …”