Synthesis, Characterization, and Degradation Behaviors of End-Group-Functionalized Poly(trimethylene carbonate)s

Abstract

KEY WORDSPolycarbonate / Biodegradable Material / End-Group Effect / Biodegradable polymers are under investigation for biomedical, pharmaceutical applications, etc. Degradability is one of their important characters. Many factors affect the degradation rate. Besides environmental conditions, such as temperature, the degradation rate is strongly dependent on the film thickness, 1 additives such as monomer, 2 basic compounds, 3 acid drugs 4 or superoxide ion, 5 and catalyst such as SnOct 2 or zinc metal, 6-9 etc. The molecular architecture, 10-13 hydrophilicity, 14-16 reasonable crosslink, 17,18 and surface modification 19,20 have vital influence on the degradation properties, too.End-group effect is demonstrable on the degradation rate. 21 It was shown that poly(lactide-co-glicolide) (PLGA) with a free carboxyl group at the polymer terminus (uncapped PLGA) degrades faster than PLGA with a hydrophobic alkyl ester linkage at the polymer terminus (capped PLGA). 22 Lee 21 synthesized various end-group-functionalized, such as OH-, NH 2 -, Cl-, or COOH-terminated polylactides (PLAs) and found that the COOH end group plays a crucial role in the hydrolysis degradation in both alkaline and acidic medium. Protection of OH end group results in a substantial retarded degradation. 23 Polyanhydrides capped with fatty terminals also show a significantly slow degradation and drug release rate. 24 Linear aliphatic polycarbonates, such as poly(1,3-trimethylene carbonate) (PTMC), have been shown to be potential for use as medical implants and for drugdelivery applications. 25 But they degrade unexpectedly slow. 10 Many efforts have been made to enhance their degradation rate. Copolymers of PTMC were synthesized for adapting to applications requiring different degradation rates and mechanical properties. 10,[26][27][28][29] Pendant hydroxyl groups have been introduced to improve the hydrophilicity and hence the degradability. 30 Since end groups have special effect on degradation rate, end-group functionalized polycarbonates will have different degradation rate. Because the polymers of multiarm architecture have a higher end-group concentration than linear polymers of the same molecular weights, the multiarm structure can strengthen the end group effect. Some researchers have synthesized the OH-terminated PTMC by ring-opening polymerization (ROP), but the degradability has not been involved up to now. 31 In the present study, we synthesize PTMC with different number of arms terminated by hydroxyl group or carboxylic group and study the degradability of such end-group-functionalized PTMCs preliminarily. EXPERIMENTAL 1,3-Trimethylene carbonate (TMC) was synthesized according to the reported method. 32 All other regents were treated just before use. Synthesis of OH-Terminated PTMC (OH-PTMC)The ring-opening polymerizations (ROP) of TMC initiated by alcohols are illustrated in Scheme 1. These polymerization reactions were carried out in the melt bulk. All reaction reagents were used just after treated. A known amount of TMC was charged ...

Synthesis and characterization of poly(ε-caprolactone) and copolyesters by catalysis with molybdenum compounds: polymers with acid-functional asymmetric telechelic architecture

“…Vials were stoppered with a rubber septum and placed in a thermostated bath at 150 8C. In the case of the Ammonium decamolybdate (NH 4 ) 8 [17]. Final polymer was crystallized from chloroform/methanol and dried under vacuum.…”

“…At the same time, biodegradability of polylactones increases as the content of -COOH groups is higher [6]. Some examples found in the recent literature follow: (1) polylactide [7] and poly(trimethylene carbonate) [8] with carboxylic acid end groups; (2) block copolymer of CL and 2-methyl-2-carboxyl-propylene carbonate, with pendant carboxyl groups [9].…”

Synthesis and Characterization of OH-Terminated Poly(trimethylene carbonate)s by Alcohol-Initiated Ring-Opening Polymerization in Melt Bulk without Using Any Catalyst

“…Alcohol-initiated ring-opening polymerization (ROP) is a convenient method of choice for the preparation of OH-terminated PTMC. 1,3 This method was also used to synthesize OH-terminated polyesters, such as polycaprolactone, poly(lactide-co-glycolide), or polylactide, etc. [4][5][6][7][8][9][10][11][12] Several metal complexes have been usually chosen as catalysts, especially metal carboxylates and alkoxides, such as stannous octoate (SnOct 2 ) and aluminum isopropoxide.…”

Aplicaciones de la tecnología de radiación de microondas en la síntesis de biomateriales

“…Los poli(alquil carbonato)s (PACs) son una familia muy versátil de biomateriales normalmente sintetizados por la ROP de carbonato de trimetileno y sus derivados sustituidos en presencia de catalizadores metálicos [130,131]. Las propiedades más interesantes de estos materiales son buena biocompatibilidad, baja toxicidad y propiedades mecánicas ajustables de acuerdo a la aplicación [132].…”

“…horas [131]. Por ello, la implementación de una tecnología que permita acortar el tiempo de reacción aparece como muy atractiva.…”