Polyether-Thiourea-Siloxane Copolymer Based on H-Bonding Interaction for Marine Antifouling.

By introducing thiourea and ether groups into MQ silicone resin polymer via free radical polymerization, a polyether-thiourea-siloxane (PTS) copolymer was synthesized. The characterization of the synthesized copolymer indicated the occurrence of H-bonding interactions and a narrow molecular weight polydispersity index. Antifouling coatings were produced by incorporating the synthesized copolymer and phenylmethylsilicone oil (PSO). The addition of a minute amount of copolymer enhanced the hydrophobicity of the coating by increasing its surface roughness. However, excessive addition of copolymer resulted in a significant deterioration of the coating surface smoothness. The copolymer improved the mechanical properties of the coating, but excessive addition decreased the crosslinking density and weakened the mechanical performance. With increasing copolymer addition, the leaching of PSO was significantly improved due to the change in the storage form of PSO in the coating caused by the copolymer. Based on the H-bonding interaction of the copolymer, the adhesion strength between the coating and the substrate was significantly improved. However, excessive addition of copolymer did not infinitely enhance the adhesion strength. The antifouling performance demonstrated that an appropriate amount of copolymer could obtain adequate PSO leaching efficiency, thereby effectively enhancing the antifouling performance of the coating. In this study, the prepared coating P12 (12 g of PTS in 100 g of PDMS) showed the most effective antifouling performance.

Improved heat resistance properties of poly(l-lactide)/basalt fiber biocomposites with high crystallinity under forming hybrid-crystalline morphology.

In this work, the heat resistance and thermomechanical properties of biodegradable poly(l­lactide) (PLLA) was improved greatly by using short basalt fibers (SBF). The heat deformation temperature (HDT) of PLLA/SBF composites was markedly improved from 62.5 to158.8 °C when its crystallinity was increased from 44.3% to 67.7% after appropriate thermal treatment. Fibers reinforcement and interface crystalline morphology were the two important reasons for the change of in heat deformation and storage modulus of PLLA before and after crystallization. Polarized optical microscopy (POM) demonstrated that the transcrystalline and shish-kebab were successfully induced by SBF, and the "crystalline-network" structure was formed in the composites after isothermal treatment. The PLLA/SBF composites with the formation of interface crystalline had a significantly higher overall heat resistance compared with the common PLLA. As the scanning electron microscope (SEM) analysis, the low values of impact strength might be due to the presence of large spherulites cracks and weak interfacial adhesion.

High-performance biodegradable polylactide composites fabricated using a novel plasticizer and functionalized eggshell powder.

A novel polyester poly(diethylene glycol succinate) (PDEGS) was synthesized and evaluated as a plasticizer for polylactide (PLA) in this study. Meanwhile, an effective sustainable filler, functionalized eggshell powder (FES) with a surface layer of calcium phenyphosphonate was also prepared. Then, PLA biocomposites were prepared from FES and PDEGS using a facile melt blending process. The addition of 15 wt% PDEGS as plasticizer showed good miscibility with PLA macromolecules and increased the chain mobility of PLA. The crystallization kinetics of PLA composites revealed that the highly effective nucleating FES significantly improved the crystallization ability of PLA at both of non-isothermal and isothermal conditions. In addition, the effective plasticizer and well-dispersed FES increased the elongation at break from 6% of pure PLA to over 200% for all of the plasticized PLA composites. These biodegradable PLA biocomposites, coupled with excellent crystallization ability and tunable mechanical properties, demonstrate their potential as alternatives to traditional commodity plastics.

Polycaprolactone nanocomposite reinforced by bioresource starch-based nanoparticles.

Biodegradable polymer nanocomposites with bioresource starch-based nanoparticles (SNPs) as reinforcing fillers for polycaprolactone (PCL) were prepared by melt blending. Scanning electron microscopy observation revealed that SNPs as spherical particles were evenly dispersed in the PCL matrix without any aggregation even with the content of SNPs increasing to 10wt% in the nanocomposite. Consequently, the rheological performances of PCL have been improved efficaciously after incorporation with SNPs as well as mechanical properties, especially with a percolation network structure of SNPs in the PCL matrix formed. In addition, the enzymatic hydrolysis experiments showed a more interesting behavior that the hydrolysis rates had been accelerated apparently in the nanocomposites than that in the neat PCL as observed. Such high performance nanocomposites may have great potential in expanding the utilization of starch from sustainable resources and the practical application of PCL-based biodegradable materials.