Novel hyperbranched poly(urethane–imide)s with enhanced thermal, mechanical, and UV-shielding properties:

A series of novel hyperbranched poly(urethane-imide)s (HBPUIs) was synthesized and derived from as-prepared imide-containing glycol and commercial materials via an A(2) + B-2 + B-3 approach. The chemical and morphological structures of the resulting polymers were evaluated by infrared attenuated total reflection and X-ray diffraction techniques, respectively. Compared with pure HBPU, HBPUIs exhibited better thermal stability with the 10% weight loss temperature of 282-298 degrees C under nitrogen atmosphere, good mechanical property with the tensile strength of 2-19 MPa, and elongation at breaks of 461-896%. Moreover, optical transmissivity of all films was measured and the results showed that they had excellent transparency in the scope of visible light. Meanwhile, the cutoff wavelengths of as-prepared HBPUI films were at around 350 nm, which can block the whole ultraviolet (UV)-C (200-280 nm) and UV-B (280-320 nm), as well as a part of UV-A (320-400 nm). Furthermore, the designed photocatalytic degradation experiment of the methylene blue (MB) confirmed that HBPUI films had good UV-shielding performance with 70% degradation of MB after intense UV irradiation (400 W) for 50 min under the protection of HBPUI film with 14% imide-containing glycol. This endowed HBPUIs with potential applications prospect in UV-shielding materials.