Poly(amic acid)s and their ionic salt solutions: Synthesis, characterization and stability study - Polyimides and Other High Temperature Polymers - page 5

Figure 3. Synthesis schematic of base poly(amic acid) (PAA), co-poly(amic acid) (Co-PAA) and
their ionic bond type photodefinable poly(amic acid) (PDPAA)s.
(Co-PAA), for example, [BPDA + o-TDA (90%) + SiDA (10%)], 38.25 g (0.13
mole) of solid BPDA powder was added to an equimolar amount of diamines
mixture [consisting of 24.84 g of o-TDA (0.117 mole) and 3.23 g of SiDA (0.013
mole)] pre-dissolved in freshly distilled NMP to make 20% solid concentrations.
The reaction mixture was stirred under a nitrogen atmosphere at room tempera-
ture overnight to make viscous polyamic or co-poly(amic acid) solutions. Then it
was filtered and packed in a polypropylene bottle under an argon environment.
2.2.1. (b) Photodefinable ionic salt formulation (PDPAA) from poly(amic acid)
(PAA) and co-poly(amic acid) (Co-PAA)
Two series of photodefinable ionic salt formulations (PDPAA) were synthesized
from the BTDA and BPDA based poly(amic acid) (PAA) and co-poly(amic acid)
(Co-PAA) with DEEM and DMEM. A stoichiometric amount of DEEM or
DMEM was added based on the calculation of theoretical mole % of free carbox-
ylic acid groups on the polymer chain from the chemical structural repeat unit.
The solution was stirred in a nitrogen environment at room temperature for two
hours and then packaged in 60 mL polypropylene bottles under an argon envi-
ronment for further study.