A three-component negative-type photosensitive branched polyamide based on an endmodified polyamide b

4

4′-methylenebis［2

6-bis(hydroxymethyl)phenol］(MBHP) as a cross-linker and a photoacid generator(5-propylulfonyloxyimino-5H-thiophen-2-ylidene)-2-(methylphenyl)acetonitrile(PTMA) has been developed.The polymer b was prepared from a branched polyamide a having degree of branching of 0.36 and cinnamyl chloride

while polymer a was sythesized from an ABB' type monomer

4-(2

4-diaminophenoxy)benzoic acid 3 in the presence of triphenyl phosphite/pyridine (TPP/Py) as a condensing agent.3 was prepared in three steps starting from the displacement of 4-hydroxybenzoic acid methyl ester with 2

4-dinitrofluorobenzene in the presence of potassium carbonate

the nitro groups of 4-(2

4-dinitrophenoxy) benzoic acid methyl ester 1 were reduced to amino groups by hydrogenation in ethyl acetate

and subsequent alkaline hydrolysis of the resulting 4-(2

4-diaminophenoxy) benzoic acid methyl ester 2.In order to avoid the effect of polymer a with amino groups on the subsequent reaction (light crosslinking) of the branched polymer

the end-modification of the amino groups was carried out by using cinnamyl chloride 5.Prior to the endmodification of polymers

the reaction of aniline 4 and 5 for determining whether the desired model compound 6 was formed in quantitative yield to constitute a polymer-forming reaction and to confirm the structure of polymers was studied.The end-modification reactions of polymer b was performed based on the reaction conditions of the model compound above described.Followed by end-modified polymer b with cinnamoyl was successfully prepared with cinnamyl chloride.The monomer 3

model compound 6 and the polymers were characterized by 1H-NMR

The average molecular weights of the polymers were determined by gel permeation chromatography(GPC).The thermal stability of the polymers was measured by thermogravimetric analysis (TGA) under a nitrogen atmosphere.The findings show that the monomer 3 and model compound 6 were successfully synthesized.Degree of branching of branched polyamide a was 0.36

caculationed from 1H-NMR

according to the definition of degree of branching given by Frey.Inherent viscosities (ηinh)

weight-average molecular weight (Mw)and polydispersity（Mw/Mn）of polymer a and b were 0.39 dL/g

0.64 dL/g

7.49×104 and 1.31×105

1.88 and 3.5

respectively.Thermogravimetric analysis (TGA) was used to measure the thermal stability of the polymers

5% weight loss temperature (Td5) of polymer a was observed at 356℃

which is higher than that of polymer b (356℃).The difference in TGA traces may be caused by the terminal cinnamoyl groups.Almost resulting polyamide a and end-capping polyamide b showed excellent solubility and readily dissolved in various solvents such as N-methyl-2-pyrrolidinone (NMP)

N

N′-dimethylacetamide (DMAc)

N

N′-dimethylformamide (DMF). The photosensitive polymer containing polymer b (85 wt%)

MBHP (10 wt%) and PTMA (5 wt%) showed a clear negative image featuring 40 μm line and space pattern when it was pre-baked at 100℃ for 10 min

subsequently exposed to a 436 nm light (g-line) and developed with a developer of DMF at 25℃ for 10 s

rinsed with water (H-2O)

post-baked at 110℃ for 3 min.