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In this paper, methacrylated γ-PGA (mPGA) precursor was synthesized via reaction between γ-PGA and glycidyl methacrylate (GMA). Hydrogels from this precursor were prepared under 365 nm ultraviolet irradiation. The swelling behavior and mechanical properties were studied in detail as functions of the degree of substitution (DS), precursor concentration, and environmental pH. Results showed that the crosslink density, swelling kinetics and mechanical properties of the hdyrogel could be tailored by adjusting the DS and concentration of the precursor as well as the environmental pH. Three-dimensional photo-encapsulation of swine cartilage chondrocytes and Live/Dead assay proved the cytocompatibility of the hydrogel. [ABSTRACT FROM AUTHOR]

Polylactide (PLA), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), and poly(butylene adipate-co-terephthalate) (PBAT) ternary blends were prepared by extrusion blending. The biodegradable PLA/P(3HB-co-4HB)/PBAT films were successfully obtained by using blown films technique. Excellent stiffness-toughness balance was achieved for 55/10/35 PLA/P(3HB-co-4HB)/PBAT film. The tensile strength reached 33.0 MPa (MD) and 23.5 MPa (TD), the elongation at break exceeded 130 %, and tear strength exceeded 110 kN/m. The Young's modulus as low as about 1800 MPa also met packaging applications. SEM observations revealed rough and long ligaments, indicating that the tear specimens were broken yieldingly. The addition of PBAT elastomers was the main reason for the improved toughness of the film. From DMA and SEM analysis, it was demonstrated that PLA, P(3HB-co-4HB), and PBAT were partially compatible. With increasing P(3HB-co-4HB) content, the melt and cold crystallization of PLA was promoted. The enzymatic degradation experiments indicated that the films had good biodegradability. These findings gave important implications for designing and manufacturing biodegradation package of high biological carbon content. [ABSTRACT FROM AUTHOR]

Efficient deep-red organic light-emitting diodes (OLEDs) were investigated based on the blend of poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) with 4,7-bis(5-(7-(9H-carbazol-9-yl)-9,9-dioctyl-9H-fluoren-2-yl)thiophen-2-yl)benzo[c] [1,2,5] thiadiazole (compound 1). By optimizing the blend ratio, the turn-on voltage of the devices was significantly reduced from 4.9 V to 2.4 V. A highest external quantum efficiency of 2.56% was achieved at a blend ratio of 95:5 (wt) for compound 1: MEH-PPV. The CIE coordinate was measured to be (0.70, 0.30), with the luminescence peak at around 680 nm. Based on experimental observations the improvement mechanism is described. [ABSTRACT FROM AUTHOR]