Versatile Copolymers from [l]-Lactide and [d]-Xylofuranose

Abstract

The new monomer 1,2-o-isopropylidene-[d]-xylofuranose-3,5-cyclic carbonate (IPXTC) was prepared. The organometallic catalysts AlR3−H2O (R = ethyl, isobutyl), ZnEt2−H2O, and Sn(Oct)2 were evaluated for the copolymerization of [l]-lactide ([l]-LA) with IPXTC. This work showed that Sn(Oct)2 was preferred for the formation of high molecular weight copolymers. For example, a copolymerization ([l]-LA/IPXTC = 83:17 mol/mol) at 120 °C for 6 h gave poly([l]-LA-co-7 mol % IPXTC) with an M n and polydispersity (M w/M n) of 78 400 and 1.9, respectively. The comonomer reactivity ratios were 4.15 and 0.255, respectively, for [l]-LA and IPXTC copolymerizations conducted at 120 °C, M/C = 200, and Sn(Oct)2 as catalyst. Structural investigations by NMR revealed that [l]-LA/IPXTC copolymers had short average IPXTC repeat unit segment lengths. Increased copolymer IPXTC content resulted in products with lower melting transition temperatures but higher glass transition temperatures. To obtain hydroxyl functionalized P([l]-LA) copolymers, the pendant IPXTC ketal protecting group was removed. The deprotection was performed in CH2Cl2 using CF3COOH/H2O without substantial molecular weight decrease. Hence, an efficient route has been developed to synthesize high molecular weight PLA-based copolymers that consist of [l]-lactic acid and [d]-xylofuranose repeat units. The [d]-xylofuranose repeat units have vicinal diol groups that will facilitate further functionalization and modification of these copolymers. The “tailorability” of the new copolymers is expected to be of great value for the development of important new bioresorbable medical materials.

Anionic Ring-Opening Copolymerization of L-Lactide with a Five-Membered Cyclic Carbonate Having a Glucopyranoside Structure

“…27,28 In order to confirm the presence of copolymeric MBCG-LL linkage in the polymerization product, we prepared two model compounds, 3a and 3b, and compared them to the copolymerization product based on their 13 C NMR spectra. The model compounds are methyl 4,6-O-benzylidene--D-glucopyranoside having an ester group at the 2-O-or 3-Oposition and a carbonate group at another position.…”

“…esters, [6][7][8][9] amides, 4,10 carbonates, [11][12][13][14][15] etc., have been prepared. We have reported the ring-opening polymerization of a fivemembered cyclic carbonate, methyl 4,6-O-benzylidene-2,3-Ocarbonyl-,D-glucopyranoside (MBCG), which was prepared from methyl -D-glucopyranoside.…”

Thermomechanical behavior and nonisothermal crystallization kinetics of poly(ε-caprolactone) and poly(ε- caprolactone)/poly(N-vinylpyrrolidone) blends

“…It can be used in different biomedical applications, such as in scaffolds, tissue engineering, and for controlled release of drugs [1][2][3][4]. By now, many researchers have synthesized PCL copolymers or blends such as PCL/PEG [5], PCL/polysaccharides [6][7][8], PCL/PVC [9], as well as incorporated various functional groups into PCL [10,11]. Even some PCL-based organic-inorganic hybrid materials have also been synthesized by sol-gel method [12].…”

Compositional analysis of biodegradable polyphosphoester copolymers using nmr spectroscopic methods

“…In recent years COSY NMR has been successfully used for the spectral characterization of novel biodegradable polymers with complex chemical linkages. 15,16 Such a two-dimensional NMR technique is very effec- tive in determining the correlations between different groups in the polymer. Finally, COSY NMR also offers the ability to determine whether any unexpected correlations or linkages may exist in the polymer and display any peak that may be hidden under or overlapped with other larger peaks and thus invisible on a regular 1 H-NMR spectrum.…”