Synthesis of Degradable Materials Based on Caprolactone and Vinyl Acetate Units Using Radical Chemistry

Abstract

Present studies are carried out with an aim to make degradable materials based on caprolactone and vinyl acetate units using radical chemistry. Radical ring-opening copolymerization of 2-methylene-1,3-dioxepane (MDO) with vinyl acetate in presence of AIBN initiator at 70 C was carried out to achieve the aim. The copolymerization introduced degradable PCL repeat units onto the C-C backbone of poly(vinyl acetate). Microstructure analysis of the copolymers is done using different 1D and 2D NMR techniques. Complete ring-opening polymerization of MDO to give ester units was observed during copolymerizations. Reactivity ratios were found out by Kelen Tüdos method and were r VAc ¼ 1:53 and r MDO ¼ 0:47 leading to statistical introduction of ester linkages onto the polymer backbone. The materials showed varied glass transition temperatures (from 37 to À44 C) depending upon the amount of ester linkages and very high elongations. The hydrolysis products were also tested for cytotoxicity studies in L929 cells and compared with that of known and accepted standard materials like poly(ethyleneimine). The hydrolysed products were non toxic and showed a cell viability > 95%. Keeping in view the combined properties like degradability, non-toxicity and low glass transition temperatures, the resulting materials could therefore be proposed for different applications like degradable gums, coatings etc.KEY WORDS: Radical Ring-Opening Polymerization / Polymer Synthesis / Degradable Polymers / Characterization / Ring-opening polymerization of "-caprolactone using anionic or metal catalysts is conventionally used for the synthesis of polycaprolactone (PCL), a well studied and in-demand degradable aliphatic polyester.1-7 A less known route to the formation of poly(caprolactone), first shown by Bailey et al. and later followed by some others, 9,10 is by radical ringopening polymerization of 2-methylene-1,3-dioxepane (MDO). 2-methylene-1,3-dioxepane is an interesting cyclic ketene acetal monomer giving poly("-caprolactone) (PCL), on the radical-ring-opening homopolymerization (RROP) and can introduce ester groups onto the vinyl polymer backbones during copolymerizations with vinyl monomers. The careful examination of 13C and 1 H NMR spectra by us 11 showed the occurrence of 100% ring-opening polymerization but the presence of about 9% branched structures in the resulting homopolymer obtained by RROP of MDO. This method of making ester linkages could be very well utilized for introducing degradability onto the nondegradable vinyl polymer backbones by copolymerizations. Also, the homopolymerization and copolymerization behaviour of different cyclic ketene acetals with some vinyl monomers like MMA, vinyl anisole, styrene etc. is reported by us 11-18 and others. 10,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The main problem during the copolymerization is the huge reactivity difference between the CKA and the vinyl monomers leading to either low molecular weight homo vinyl polymers without ester linkages or copolymers incorpor...

Computational Package for Copolymerization Reactivity Ratio Estimation: Improved Access to the Error-in-Variables-Model

“…Exhibit A presents an overview of recent literature [10][11][12][13] regarding the copolymerization of 2- Another important piece of information is the degree of parameter correlation, which can be evaluated according to the slope of the JCR. Parameter correlation is something that should be avoided as much as possible and can be minimized by using designed experiments.…”

“…Exhibit A presents an overview of recent literature [10][11][12][13] regarding the copolymerization of 2-methylene-1,3-dioxepane (MDO; monomer 1) and vinyl acetate (VAc; monomer 2) (see also Table 1; RR stands for reactivity ratio). This copolymer has gained considerable attention in the past decade, largely due to its degradable properties.…”

“…Hence, the cumulative and instantaneous mole fractions in the copolymer are about the same. This experimental fact (and subsequent analysis) is considered "best practice," and is used throughout the reactivity ratio estimation literature (see, for example, [10,[12][13][14]16,17]). …”

Functional Degradable Polymers via Radical Ring‐Opening Polymerization and Click Chemistry

“…We have used this method to prepare a new class of polymers poly(vinyl-co-ester)s by copolymerizing vinyl monomers with CKAs. [16][17][18][19][20][21] For example, the RROP of 2-methylene-1,3-dioxepane gives polycaprolactone. [ 20 ] Interestingly, the reaction product of each vinyl monomer with CKAs generates a resulting polymer with unique properties.…”

Synthesis of High‐Molecular‐Weight Tulipalin‐A‐Based Polymers by Simple Mixing and Heating of Comonomers

“…Already in our laboratory, we have synthesized a large number of such degradable and useful polymers. [15][16][17][18][19][20][21][22][23] Keeping in view the desire of having a degradable, high glass transition temperature polymer with good processability and solubility in various organic solvents having complete or partial bio-base for many different applications including packaging, we aim at modifying the properties of poly(MBL). For this aim, copolymerization of MBL was carried out with cyclic ketene acetal, 2-methylene-1,3-dioxepane (MDO), providing not only the degradable polycaprolactone units by ROP of MDO but also the flexibility and solubility in organic solvents for better processability.…”