Yellow colored viscous poly(amic acid
) (PAA) was obtained.
After the formation of amic acid
linkages between maleic anhydride units of PSMA and three aromatic amines (AS, AIPA, and 6FAL), a free radical polymerization inhibitor (BHT) and a chemical imidization agent (acetic anhydride; 10 mL) were added and the reaction mixture was reacted for 4.5 h at 100 [degrees]C to afford side-chain polyimides (PSI-x)  (Figure 2).
Designed as an alternative to polymers that are water-soluble only in high-pH, alkaline solutions, these SMA 1000MA amic acid
resins are said to eliminate the tarnish typical with bronze and copper dispersion while producing a pigment with "true metallic color."
This resin contains amic acid
functionality, groups that are possible to form only with anhydride-containing resins.
The most used method for the synthesis of aromatic polyimides via soluble poly(amic acid
) precursors has disadvantages connected with the low stability of the poly(amic acid
) solutions and incomplete cyclization of the poly(amic acid
)s to polyimide structures (1), (2).
An amic acid
modfiled base resin is nonionic in nature and is soluble at a pH of 7.
The poly(amic acid
) (PAA) precursor solution was prepared through poly-condensation reaction between BPDA and PDA in NMP.
Poly (amic acid
) (PAA) hybrids with organically modified montmorillonite (Cloisite 30B) were synthesized from N, N'-dimeihylacelamide (DMAc) solution.
The hybrid films were prepared using a poly (amic acid
) having phthalide groups and tetraethoxysilane via solgel technique and thermal cyclodehydration.
Therefore, the processing of the polyimides is generally carried out via soluble poly(amic acid
) precursors, which are cast onto various substrates, and then they are converted into polyimide films by thermal treatment.
In this novel process, termed solid-state powder foaming by the authors, poly(amic acid
) (PAA) precursor powders are prepared by reacting aromatic diacid-diesters with aromatic diamines in the presence of a hydrogen bonding solvent (e.g., tetrahydrofuran, THF and methanol, MeOH).
Polyimide foams and microstructures discussed in the present work were obtained by thermal treatment of poly (amic acid
) solid phase precursor powders containing solvents that act as BAs [1-4].