END-MODIFIED POLYAMIDE/PHOTOACID GENERATOR/CROSSLINKER THREE-COMPONENT-NEGATIVE-TYPE PHOTOSENSITIVE BRANCHED POLYAMIDE

Abstract

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 (η_ inh ),weight-average molecular weight (M_w)and polydispersity (M_w/M_n)of polymer a and b were 0.39 dL/g,0.64 dL/g,7.49×10~4 and 1.31×10~5,1.88 and 3.5, respectively.Thermogravimetric analysis (TGA) was used to measure the thermal stability of the polymers,5% weight loss temperature (T_ d5 ) 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.