Polymer/Polymer Inclusion Compounds as a Novel Approach To Obtaining a PLLA/PCL Intimately Compatible Blend

Abstract

Introduction. Aliphatic polyesters represent an important family of biodegradable materials. Increasing attention has been focused on hydrolytically unstable lactone polymers owing to their usefulness in biomedical applications.To enhance the rate of biodegradation, the permeability and the tensile properties of the biomaterials, copolymerization, and blending processes have been used. Blending with other biodegradable polymers might offer a more cost-effective way of modifying the properties of hard and brittle poly(L-lactic acid) (PLLA) than chemical modification. 1,2 Previously, several blend systems containing PLLA have been investigated, such as PLLA/poly(ethylene oxide) (PEO), 3,4 PLLA/poly(DLlactide) (PDLLA), 5-7 PLLA/PEO-poly(propylene oxide)-PEO copolymers, 8 PLLA/poly(3-hydroxybutyrate) (PHB), 9 PLLA/poly( -caprolactone) (PCL), 9 and PLLA/poly(pvinylphenol) PVPh. 10 However, most of the blends were found to be immiscible, including a phase-separated morphology identified for PLLA/PCL blends. 9 Taking advantage of the ability of R-cyclodextrin (R-CD) to form inclusion compounds (ICs) with both PLLA and PCL, an intimately compatible blend can be achieved when PLLA/PCL-R-CD IC was obtained and afterward washed with a solvent (H 2 O) for the R-CD host, which is a nonsolvent for the guest polymers.Recently, we have reported that R-CD forms a crystalline IC with high molecular weight PCL. 11 Here, we have also found that R-CD can form complexes with PLLA (M w ) 285 000), as well as simultaneously with PLLA and PCL.The miscibility of the PLLA/PCL blend extracted from R-CD IC channels has been investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and polarizing optical microscopy. These preliminary results are compared to those of a PLLA/PCL blend cast from their common solution in dioxane.Experimental Section. a. r-CD IC Formation. A heated solution (50 °C) of PCL (0.4 g, 3.5 mmol in monomer unit, M w ) 65 000) and PLLA (0.25 g, 3.5 mmol in monomer unit, M w ) 285 000) in dioxane (200 mL) was slowly added to 50 mL of an aqueous solution saturated with R-CD (7.25 g, 7.5 mmol) also held at 50 °C. After 1 h of stirring at 50 °C, the solution was allowed to cool to room temperature while continuously stirring for another 24 h. A white powder was collected

Molecular Processing of Polymers with Cyclodextrins

“…13). The rapid solidification of PCL and PLLA upon coalescence [12] implies a potentially improved dispersion of the drug in the PCL and PLLA matrices, which likely will critically impact their ability to deliver drugs.…”

Preparation and Characterization of PEG/PLA Multiblock and Triblock Copolymer

“…[1][2][3][4][5] As a non-biodegradable but biocompatible polymer, PEG has been used for many clinical applications. 6 PEG presents outstanding properties, such as hydrophilicity, solubility in water and in organic solvents, nontoxicity, and absence of antigenicity and immunogenicity.…”

“…In the last two decades, various synthetic methods have been developed to prepare a variety of PLA/PEG related copolymers with different structures and compositions. These copolymers can be classified according to their block structure as diblock, 5 triblock,…”

Preparation of Highly Transparent and Thermally Stable Films of α‐Cyclodextrin/Polymer Inclusion Complexes

“…[1] Since Harada et al found that many a-CDs can thread onto a poly(ethylene glycol) (PEG) chain to form a crystalline inclusion complex (IC), [2] it has been found that CDs form ICs with several biodegradable aliphatic polymers, such as PCL, [3] poly(3-hydroxybutyrate), [4] poly(butylene succinate), [5] and their copolymers. [6][7][8] The formation [9,10] and properties of CD-ICs with various polymers have been studied to improve miscibility, [11][12][13] biodegradation, [14] and crystallization of polymers. [15] By threading a-CD molecules, some physical properties of the polymers are changed.…”