Stimuli-degradable polymers are regarded as interesting materials for various applications like patterning or drug delivery. In particular, light as a trigger received a lot of attention due to the possibility of adjusting wavelength, light intensity and irradiation time, which leads to a precise and controlled application. In this study, we report the synthesis of two novel light-degradable polyurethanes which are based on 6-nitropiperonal and differ in the implementation of the light-cleavable unit. Degradation of these backbone- or side-chain-cleavable polymers was analyzed by UV/Vis spectroscopy and SEC. While both polymers showed rapid decomposition in solution, differences in the degradation rates were observed dependent on the incorporation site of the light-cleavable unit. Furthermore, nanoparticles were fabricated and characterized by photon correlation spectroscopy as well as scanning electron microscopy proving the processability of the polymers for potential application as, e.g., a controlled release system.

中文翻译：

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主链与侧链：两种基于 6-硝基胡椒醛的光降解聚氨酯

可刺激降解聚合物被认为是用于各种应用（例如图案化或药物递送）的有趣材料。尤其是光作为触发器，由于可以调整波长、光强度和照射时间，从而实现了精确可控的应用，因此受到了很多关注。在这项研究中，我们报告了两种新型光降解聚氨酯的合成，它们基于 6-硝基胡椒醛并且在光可裂解单元的实施方面有所不同。这些主链或侧链可裂解聚合物的降解通过紫外/可见光谱和 SEC 进行分析。虽然两种聚合物在溶液中都显示出快速分解，但观察到降解速率的差异取决于光可裂解单元的掺入位点。此外，例如，受控释放系统。