Tham khảo tài liệu 'features of liquid crystal display materials and processes part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Polyimides Bearing Long-Chain Alkyl Groups and Their Application for LiqUid Crystal Alignment Layer and Printed Electronics 9 Solubility As far as the solublity of polyimides based on long-chain alkyl groups is concerned the following interesting results have been obtained. Experimental results of homopolymerization and copolymerization based on BTDA ADBP-12 AODB-12 DBAE-12 ADBA-12 DPABA-12 DDE are summarized in Table 1. Although all polyamic acid s were soluble in NMP which is a solvent used for polymerization however the solubility of homopolyimides and copolyimides depended on polymer structures. BTDA ADBP-12 homopolyimides and BTDA ADBP-12 DDE copolyimides containing 40 mol of ADBP or more were soluble in NMP. Thus the effect of long-chain alkyl group in ADBP for the enhancement of solubility was confirmed. BTDA AODB-12 homopolyimides and BTDA AODB-12 DDE copolyimides containing 25 mol or more of AODB-12 units were also soluble in NMP. Judging from the results of copolymerization based on BTDA ADBP-9 14 DDE and BTDA AODB-10 14 DDE it is recognized that AODB bearing alkyl groups via an ether linkage were more effective for the enhancement of solubility in comparison to ADBP. On the other hand all homopolyimides and copolyimide based on BTDA DBAE-8 14 DDE were insoluble in NMP probably due to the rigid ester linkage groups. The experimental results of copolymerization based on BTDA ADBA-12 DDE are quite unique. Although BTDA ADBA-12 homopolyimide was insoluble the copolymers BTDA ADBA-12 DdE 100 75 25 and BTDA ADBA-12 DDE 100 50 50 were soluble in nMp. The solubility of these copolyimides may be improved by the randomizing effect based on copolymerization as well as the entropy effect of long chain linear alkyl groups. Based on the fact that all copolyimides BTDA DBAE-8 14 DDE were insoluble in NMP ADBA is more effective for the enhancement of solubility in comparison to DBAE. Fig. 6 summarizes the effect of functional diamines AODB-X ADBP-X ADBA-X and .
