Preparation of Biodegradable Cationic Polycarbonates and Hydrogels through the Direct Polymerization of Quaternized Cyclic Carbonates

Abstract

Polymers exhibiting both antimicrobial and biodegradable properties are of great interest for next generation materials in healthcare. Among those, cationic polycarbonates are one of the most promising classes of materials because of their biodegradability, low toxicity, and biocompatibility. They are typically prepared by a chemical postmodification after the polymer has been synthesized. The main problem with the latter is the challenges of ensuring and verifying complete quaternization within the polymer structure. Herein, we report the first example of synthesizing and polymerizing charged aliphatic cyclic carbonates with three different alkane pendant groups (N-methyl, N-butyl, and N-hexyl) by ring-opening polymerization (ROP). These charged eight-membered cyclic carbonates displayed extraordinary reactivity and were even polymerizable in polar solvents (e.g., DMSO) and in catalyst free conditions that are generally unobtainable for other ring opening polymerization processes. A computational study was carried out and the findings were in agreement with the experimental data in regards to the dramatic increase in reactivity of the charged monomer over their neutral analogs. Furthermore, a series of hydrogels were prepared using the different charged eight-membered cyclic carbonates, and we found it to have a significant impact on the hydrogels’ ability to swell and degrade in water. Finally, the hydrogels demonstrated antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). These materials could be ideal candidates for biologically relevant applications where cationic structure is required.

Studying the Ring-Opening Polymerization of 1,5-Dioxepan-2-one with Organocatalysts

“…Among the various organocatalysts, the most studied were phosphazenes, guanidines, and amidines. Hedrick and coworkers have prepared polycarbonates, polylactides with excellent controlling and functionality using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the organocatalysts [17,18,19,20,21,22]. Zhao and Zhang’s group have developed a number of poly(ethylene oxide) based copolymers and polymerization methods with phosphazene catalysts [23,24,25,26].…”

Biodegradable Polycarbonate Iongels for Electrophysiology Measurements

“…Polycarbonates based on N -substituted cyclic carbonates are receiving growing attention in recent years for their potential applications to biological and medical engineering [18,19,24]. In this work, we prepared polycarbonate-based iongels via one-step ring-opening polymerization, as illustrated in Scheme 1.…”

“…Recently, Sardon and coworkers explored the use of N -substituted eight membered cyclic carbonate monomers to obtain polycarbonates intended for the biomedical field [18,19]. In this work, we prepared polycarbonate matrices by direct polymerization of cyclic carbonates in the presence of bifunctional cyclic carbonates and PEG-diol.…”

Organocatalytic Synthesis of Alkyne‐Functional Aliphatic Polycarbonates via Ring‐Opening Polymerization of an Eight‐Membered‐N‐Cyclic Carbonate

“…[ 34–38 ] Recently, a new class of strained 8‐membered cyclic carbonates derived from diethanolamine (2,2′‐dihydroxydiethylamine) were prepared and polymerized to well‐defined N ‐substituted polycarbonates. [ 39–45 ] The N ‐substitution not only enhanced the ring strain, thus increasing the reactivity of the carbonate, but also provided a synthetic handle to introduce functionality. Tailoring the functionality of these polymers has been successfully accomplished through their post‐ROP functionalization as well as through the preparation of functionalized monomers.…”