| 摘要 |
A polyolefin is functionalized with two, three, or more terminal coumarin groups. When irradiated with longer wavelength ultraviolet light (e.g., 365 nanometers), the coumarin groups cyclodimerize to form a chain-extended or crosslinked polyolefin. The cyclodimerization can be reversed by irradiation with shorter wavelength ultraviolet light (e.g., 254 nanometers). When the crosslinked polyolefin is used to form a barrier layer in a light emitting diode or a photovoltaic device, scratches in the barrier layer cleave the cyclodimer groups and can be “healed” by irradiation to reduce or remove the scratches. |
| 主权项 |
1. A compound of the following formula: wherein:
L is a multivalent initiator residue;k is an integer greater than or equal to 2;A for each occurrence independently is selected from —NRa—, —O—, or —OC(O)—, wherein Ra is a H or a C1-C4 alkyl;R3, R4, R5 for each occurrence independently is each independently selected from H, C1-C6 alkyl, C2-C6 alkenyl, amino, C1-C6 alkoxy, —C(O)ORa, hydroxy, or a halogen;n for each occurrence independently is an integer not less than 2;m for each occurrence independently is 0, 1, 2 or 3;R1 for each occurrence independently is H or a C1-C4 alkyl, a C1-C6 alkoxy or a substituted or unsubstituted aryl; andR2 for each occurrence independently is H, X2, CH2X2, CHX22, CX23, CN, or NO2, wherein X2, for each occurrence, is independently a halogen. |
