Preparation and characterization of poly(lactic acid) composites involving aromatic diboronic acid and organically modified montmorillonite

In this study, composites of polylactide, PLA, involving 1, 2 and 3 mass% 1,4-benzene diboronic acid, BDBA, in the absence and presence of 3 mass% organically modified montmorillonite, Cloisite 30B, C30B, were prepared and characterized. Homogenous dispersion for the composites involving only 1 mass% BDBA and agglomeration for the ones with higher BDBA content were observed. For the composites involving nanoclay, mainly intercalated dispersion was detected. Both TGA and DP-MS results indicated a decrease in thermal stability upon the addition of 1 mass% BDBA. However, as the amount of BDBA incorporated into PLA matrix was increased, thermal stability was also increased. Trans-esterification reactions between BDBA and PLA, although caused decomposition of PLA chains at low concentrations of BDBA to a certain extent, at high concentrations generated a cross-linked structure increasing thermal stability. In the presence of C30B, thermal stability of the composites was increased further. This behavior was associated with enhanced interactions of BDBA and PLA upon diffusion into clay layers.