Aliphatic Polycarbonates with Controlled Quantities of d-Xylofuranose in the Main Chain

Abstract

Polycarbonates were synthesized by ring-opening copolymerizations of trimethylene carbonate (TMC) with 1,2-O-isopropylidene-d-xylofuranose-3,5-cyclic carbonate (IPXTC). Subsequent deprotection of the ketal protecting groups gave controlled quantities of vicinal diol pendant groups. Studies of TMC/IPXTC copolymerization showed that MAO and ZnEt2−0.5H2O were the preferred catalysts. The reactivity ratios measured by the Fineman−Ross method and using ZnEt2−0.5H2O as the catalyst were 0.31 and 0.20 for IPXTC and TMC, respectively. Hence, even though IPXTC has bulky substituents, IPXTC was more reactive than TMC early in the copolymerization. Consistent with the above, the average IPXTC chain segment length was longer early in the copolymerization but decreased with increased conversion. 1H and 13C NMR were used to analyze the repeat unit sequence distribution of copolymers. For copolymers with high IPXTC contents, three types of IPXTC linkages were found: head−head, tail−tail, and head−tail. The protecting ketal groups were removed by CF3COOH/H2O to give a novel polycarbonate with hydroxyl pendant groups. Longer deprotection times led to higher extents of deprotection but lower molecular weight. Studies by differential scanning calorimeter (DSC) showed that copolymers having from 8 to 83% IPXTC were all amorphous. In addition, a physical aging transition was apparent. The T g of the copolymer increased with increasing IPXTC copolymer content. Furthermore, the experimental T g values were in good agreement with that calculated by the Fox equation. After deprotection, the copolymer T g decreased, which is consistent with the loss of the bulky ketal side group.

Core Crosslinking of Biodegradable Block Copolymer Micelles Based on Poly(ester carbonate)

“…Nevertheless, for medical application, an equally important aspect is the biocompatibility and biodegradability of the material. Aliphatic polyesters and polycarbonates are biocompatible, biodegradable, and nontoxic materials 25–27. However, few studies of crosslinked micelles based on biodegradable poly(ester carbonate) have been reported.…”

Nucleophile-initiated and thermal bulk polymerizations of cyclic trimethylene carbonate in the absence of added catalysts

“…The polymerization can be achieved using a large variety of intiators: anionic, [1][2][3][4][5][6][7] cationic [4,[8][9][10] and of coordination-insertion type. [11][12][13][14][15][16][17] Very recently the enzymatic polymerization has also been developed. [18][19][20] The continuous interest in aliphatic polycarbonates results from their potential applications in several attractive domains.…”

Polycarbonates from Sugars: Ring-Opening Polymerization of 1,2-O-Isopropylidene-d-Xylofuranose-3,5- Cyclic Carbonate (IPXTC)

“…16,17 The general polymerization protocol and polymer characterization methods were also previously published. 16,17 Organometallic catalysts that contain aluminum, zinc and rare-earth metals as well as t BuOK were evaluated for their abilities to homopolymerize IPXTC. The results of this work are summarized in Tables 1 and 2.…”

“…The pendant ketal groups along P(LA-co-IPXTC) chains were transformed to vicinal diol groups by using CF 3 COOH/H 2 O. 16,17 Similar attempts to reach high extents of ketal deprotection for P(IPXTC) were carried out. P(IPXTC) that was soluble in CHCl 3 , CH 2 Cl 2 , and THF became insoluble in these solvents after the deprotection experiments.…”