RAFT Polymerization of a Biorenewable/Sustainable Monomer via a Green Process

Abstract

A biorenewable polymer is synthesized via a green process using the RAFT principle for the first time in supercritical CO2 at 300 bar and 80 °C. α‐Methylene‐γ‐butyrolactone polymers of various chain lengths and molecular weights are obtained. The molecular weights vary from 10 000 up to 20 000 with low polydispersity indexes (PDI <1.5). Furthermore, the monomer conversion in supercritical CO2 is substantially higher, respectively 85% for ScCO2 compared to ≈65% for polymerizations conducted in dimethyl formamide (DMF) solvent. Chain extensions are carried out to confirm the livingness of the formed polymers in ScCO2. This opens up future possibilities of the formation of different polymer architectures in ScCO2. The polymers synthesized in ScCO2 have glass transition temperature (Tg) values ranging from 155 up to 190 °C. However, the presence of residual monomer encapsulated inside the formed polymer matrix affects the glass transition of the polymer that is lowered by increasing monomer concentrations. Hence, additional research is required to eliminate the remaining monomer concentration in the polymer matrix in order to arrive at the optimal Tg.

Initiated Chemical Vapor Deposition (iCVD) of Bio-Based Poly(tulipalin A) Coatings: Structure and Material Properties

“…A peak between 2840 and 3000 cm −1 was assigned to C-H stretching in both the monomer and the polymer spectra. The broadest peak at 1760 cm −1 for both α-MBL and PMBL spectra was attributed to the C=O lactone stretching, and it corresponds to the reported C=O stretching in gamma-butyrolactone moieties [ 19 ]. This peak was compared to previously reported IR spectra of PMBL obtained via solution-phase RAFT polymerization, and it was confirmed that polymerization occurred by vinyl addition rather than ring opening [ 3 , 11 ].…”

“…This peak was compared to previously reported IR spectra of PMBL obtained via solution-phase RAFT polymerization, and it was confirmed that polymerization occurred by vinyl addition rather than ring opening [ 3 , 11 ]. The 1664 cm −1 peak attributed to the C=C stretching in the FTIR spectrum of the monomer (α-MBL) is no longer observed in the polymer spectrum, which proves the completion of the polymerization reaction without the presence of any remaining monomer [ 3 , 11 , 19 ]. Another peak between 1440 and 1500 cm −1 was assigned to methylene C-H bending [ 11 ].…”

“…Butyrolactone sustainable polymers have been previously synthesized via a wide range of free-radical polymerization (FRP) techniques, such as conventional FRP [ 11 , 12 , 13 , 14 , 15 , 16 ], atom-transfer radical polymerization (ATRP) [ 17 ], and reversible-addition fragmentation chain transfer (RAFT) [ 5 , 18 , 19 , 20 ]. Despite the interesting and unique properties of those monomers and their polymers, their polymerization studies are still relatively scarce in the literature and were mainly carried out in highly toxic organic solvents to produce bulk polymers, at low monomer conversions [ 5 ].…”

“…Among the most famous γ-butyrolactone monomers is α-methylene-γ-butyrolactone (α-MBL, Tulipalin A) [ 5 , 11 , 17 , 19 , 21 , 22 ], which can be directly derived from tulips (Tulipa gesneriana L) that are widespread in the Netherlands [ 23 ]. It has the strongest resemblance to the widely used methyl methacrylate (MMA) monomer and was therefore chosen as the focus of this work.…”

“…α-MBL has a five-membered lactone ring ( Figure 1 ), which can be used for hydrolyzable drug bonding as well as in co-polymerization by ring-opening polymerizations (ROP) [ 24 ]. The lactone ring can thus be used in analogous reactions to make new bio-based materials with various characteristics [ 15 , 19 ]. Additionally, α-MBL has sites where specific biomolecules can be attached for targeted drug delivery, which would serve as an interesting research pathway for novel drug delivery systems [ 25 ].…”