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An active film was prepared from chitosan incorporated with montmorillonite (MMT) and pomegranate rind powder extract (PRP). The effect of MMT (1 %, 3 %, and 5 % w/w chitosan) and PRP (1 %, 1.5 %, and 2 % w/v chitosan) on the physical, mechanical and antioxidant properties of the chitosan-based films was studied. Fourier transform infrared (FTIR) spectra revealed that good interactions occurred between functional groups of chitosan with MMT or with PRP. The results showed that the water vapor barrier property of the films was significantly improved by incorporation of MMT and PRP (p < 0.05). When compared to pure chitosan film, the WVP of M3P2 film (Chitosan/3 % MMT/2 % PRP) decreased by 25.2 %. Tensile strength of the films was affected by the addition of MMT and PRP. However, percent elongation at break was not significantly changed by addition of PRP. The film incorporated with 3 % MMT and 2 % PRP that contained the highest amount of total phenolic (15.2 mg GAE/g DW), was found to be the most active radical scavenger. These results suggest that chitosan films containing MMT and PRP can be used for development of active food packaging materials.

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The synthesis of hydroxy-terminated poly(ethylene glycol)-co-poly(ε-caprolactone) (MPEG−PCL) was investigated by the reaction of poly(ethylene glycol) and ε-caprolactone in the presence of stannous octoate. The polymerization was proved to be carried out in a controllable way. Bromo-terminated MPEG−PCL copolymer has been synthesized by macromolecular reaction as a possible method to prepare primary amino-terminated MPEG−PCL. The conversion of hydroxy-terminated MPEG−PCL to amino-terminated MPEG−PCL was detected quantitatively. The primary amino-terminated MPEG−PCL was an effective macroinitiator for the ring-opening polymerization of β-benzyl l-aspartate-N-carboxy anhydride. The A−B−C triblock copolymer of MPEG−PCL−PBLA thus synthesized may be used as a new potential biomaterial, which contains both a hydrophilic unit and a hydrophobic unit as well as functional groups.

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Nanocomposites of poly(⑀-caprolactone) (PCL) with hydroxyapatite nanocrystals (HAP) prepared through the solvent-cast technique were characterized by means of transmission electron microscopy (TEM), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and tensile tests. Such composites are of great importance to make bone-like substitutes as HAP nanocrystals have similar composition, morphology, and crystal structure as natural apatite crystals. The TEM micrograph reveals the nanocrystals dispersed homogeneously in the matrix at a microscale level. The solvent-cast samples commonly show much higher melting points and crystallinity than the melt-quenched samples, due to a lower undercooling as well as more sufficient time to crystallize. For both cases of samples, the melting point decreases slightly with HAP content while the level of crystallinity attained by the PCL component is not hindered by the nanocrystals. Both the glass transition temperatures and the nonisothermal crystallization temperatures are composition dependent. The tensile modulus increases with increasing HAP content while the yield stress is almost invariant with composition. Theoretical prediction of the modulus based on Halpin-Tsai equations shows excellent agreement with the experimental result. By analysis of the variation in fracture stress and strain with composition, a ductile-to-quasi-brittle transition is revealed to be operative for the nanocomposites, as also can be seen by SEM.

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Antimicrobial active films based on poly(lactic acid) (PLA) were prepared with poly(ε‐caprolactone) (PCL) and thymol (0, 3, 6, 9, and 12 wt%) by solvent casting methods. The films were characterized by thermal, structural, mechanical, gas barrier, and antimicrobial properties. Scanning electron microscopy analysis revealed that the surface of film became rougher with certain porosity when thymol was incorporated into the PLA/PCL blends. Thymol acted as plasticizers, which reduce the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the films. The addition of PCL into the pure PLA film decreased the glass transition temperature of the films. The presence of thymol decreased the crystallinity of PLA phase, but did not affect the thermal stability of films. Water vapor barrier properties of films slightly decreased with the increase of thymol loading. The antimicrobial properties of thymol containing films showed a significant activity against Escherichia coli and Listeria monocytogenes. The results indicated the potential of PLA/PCL/thymol composites for applications in antimicrobial packaging. Copyright © 2014 John Wiley & Sons, Ltd.