Copolymerization of Cyclic Phosphonate and Lactide: Synthetic Strategies toward Control of Amphiphilic Microstructure

Abstract

Controlling the microstructure of polymers through chemical reactivity is key to control the material properties of synthetic polymers. Herein we investigate the ring-opening copolymerization of a mixture of lactide and 2-ethyl-2-oxo-1,3,2-dioxaphospholane, promoted by an aluminum pyrrolidine monophenolate complex or 1,8-diazabicyclo[5.4.0]­undec-7-ene (DBU). This monomer mixture provides fast access to amphiphilic copolymers. The reaction conditions control the copolymer microstructure, which has been determined via a combination of 1H and 31P NMR spectroscopy. The choice of initiator has a profound impact: both initiators produce tapered block copolymers but with reverse monomer selectivity. While the aluminum initiator favors the cyclic phosphonate monomer, DBU favors lactide polymerization. Moreover, a sequential control of temperature facilitates the preparation of block copolymers in one pot. Thermal properties measured by TGA and DSC correlate to copolymer architectures. This methodology is the first report of copolymerization between cyclic phosphonates and lactide and opens the possibility to tune the thermal properties, solubility, and degradation rates of the resulting materials.

RNA-Inspired and Accelerated Degradation of Polylactide in Seawater

“… We used 1,8-diazabicyclo-[5.4.0]­undec-7-en (DBU) as an organocatalyst and prepared homopolymers of PLA and PLLA with different degrees of polymerization (entries 5, 6, 9, and 10 in Table for later comparison) . To the best of our knowledge, to date, only a single paper describes the statistical copolymerization of cyclic phosphonates with LA and DBU, while cyclic phosphates had been studied before as comonomers for LA only once with Al­(O i Pr) 3 as the catalyst . From our previous knowledge of cyclic phosphonates, a strong gradient formation was also expected during a statistical copolymerization of EVEP with LA.…”

Amphiphilic Polyphosphonate Copolymers as New Additives for PDMS-Based Antifouling Coatings

“…All of the polymers were found to be completely amorphous ( Table 2 ). Poly(alkyl ethylene phosphonate)s with short alkyl side chains are reported to have T g s around −40/−45 °C, and in particular, poly(ethyl ethylene phosphonate)s with various molecular weights exhibit T g values lower than −50 °C [ 2 , 48 ]. PEtEPMA and p(PEtEPMA) showed glass transition temperatures at ca.…”

“…In particular, main-chain PPEs are characterized by repeating phosphoester bonds in the backbone, and the pentavalent phosphorus atom can be exploited to graft different side chains, thus providing a useful tool for tuning the polymer properties [ 1 ]. Among the others, polyphosphonates are a subset of PPEs bearing an alkyl/aryl group in the side chain, linked to the phosphorus atom through a phosphonate bond [ 2 ]. The hydrolysis rate can be tuned by modifying the chemical structure of the lateral substituent, e.g., the longer and sterically bulkier the side chain is, the better it shields the main chain from nucleophilic attack [ 3 ].…”

Polyphosphonate-Based Macromolecular RAFT-CTA Enables the Synthesis of Well-Defined Block Copolymers Using Vinyl Monomers

“…PPEs are interesting as polymeric flame-retardant additives . Further, based on their nucleic acid analog structure and water-solubility, PPEs have been used in promising biomedical applications due to high levels of cytocompatibility, antifouling properties, and the so-called “stealth effect”. − A variety of strategies to access PPEs have been developed, including polycondensation, transesterification, , enzymatic polymerization, olefin metathesis, , and anionic ring-opening polymerization (AROP). , Especially, AROP was used to prepare PPE-containing amphiphilic block copolymers with PEG/polycaprolactone, − polylactide, − or side-chain functionalized PPEs as second blocks. ,, These materials have been assembled into nanoparticles for applications that range from surface protein adsorption and nanocarriers for drug or gene delivery ,, to antimicrobial nanomedical devices …”