Synthesis, characterisation and degradability of polyamides derived from aldaric acids and chain end functionalised polydimethylsiloxanes

Activated glucaric and galactaric acid derivatives were reacted with two different α,ω-diaminoalkyl polydimethylsiloxanes to give novel carbohydrate-segmented silicone polyamides, which were characterised by spectroscopic methods. Their intrinsic viscosities, Huggins constants, molecular weights and thermal properties have been determined by viscosimetric analysis, size exclusion chromatography, differential scanning calorimetry and thermal gravimetric analysis, respectively. Due to the immiscibility of carbohydrates and silicones, some of the presented materials demonstrate strong microphase separation with Tgs up to 144 °C. It could be shown, that galactaric acid segmented silicones display a higher Tg than their glucaric acid analogues. By varying the contents of glucaric and galactaric acid in a homologous series, which was dominated by cyclic products, as could be shown by MALDI TOF MS, the observed DSC signals could be shifted between 28 and 54 °C. In a first test on biodegradability, employing Proteinase XIV from Streptomyces griseus, it could be shown that this class of materials can be at least partly degraded by enzymes, with the amide bond functioning as a predetermined breaking point.