Synthesis and characterization of novel diblock copolymers of 5-(N-carbazoyl methyl)bicyclo[2.2.1]hept-2-ene and 5-(phthalimide methyl)bicyclo[2.2.1]hept-2-ene via living ring-opening metathesis polymerization

Ring-opening metathesis polymerization (ROMP) has been performed with {RuCl 2(CHPh)[P(C6H11)(3)](2)} catalyst to make low polydispersity block copolyme rs of 5-(N-carbazoyl methyl)bicyclo[2.2.1]hept-2-ene (CbzNB) and 5-(phthali mide methyl)bicyclo[2.2.1]hept-2-ene (NBMPI). Three diblock copolymers with the CbzNB and NBMPI were made, varying both molecular weight and percent o f each block. The hydrogenated diblock copolymers were successfully obtaine d by using p-toluenesulfonylhydrazide as a reducing agent. The novel dibloc k copolymers were characterized by means of gel permeation chromatography ( GPC) H-1 NMR, fluorescence, differential scanning calorimeter (DSC) and the rmogravimetric analysis (TGA). The molecular weight distributions of the di block copolymers are narrow ((M) over bar (W)/(M) over bar (n) similar to 1 .5). Unhydrogenated diblock copolymers exhibited a strong carbazole fluores cence, with monomer emission occurring in the near-UV at approximately 380 nm and extending into the blue-violet region. Similar results were also obs erved on hydrogenated diblock copolymers. All diblock copolymers exhibited good solubility in a variety of solvents such as methylene chloride, chloro form, tetrahydrofuran and 1,2-dichlorobenzene; however, there was no remark able difference between unhydrogenated and hydrogenated diblock copolymers. Two T-g values were observed for the CbzNB segment and the NBMPI segment b efore and after hydrogenation. Unhydrogenated diblock copolymers exhibited good thermo-oxidative stability, losing 10% mass in the range 369-389 degre esC in air and 400-416 degreesC in nitrogen. However, hydrogenated diblock copolymers showed better thermal stability than unhydrogenated diblock copo lymers, and 10% mass loss temperatures were recorded in the range 375-396 d egreesC in air and 415-428 degreesC in nitrogen. (C) 2001 Published by Else vier Science Ltd.