ABSTRACT:Hyperbranched polyamides with different degree of branchings (DBs) were prepared by different polycondensation conditions from an ABB 0 type monomer, 4-(2,4-diaminophenoxy)benzoic acid. Polyamide (PA1) with multi-amino groups prepared in the presence of (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonic acid diphenyl ester (DBOP) and triethylamine as condensing agents at room temperature had lower DB of 0.1. Polyamide (PA2) with multi-amino groups prepared in the presence of triphenylphosphite and pyridine as condensing agent at 100 C had higher DB of 0.2. The free amino groups of both polyamides were modified by acetyl chloride, benzoyl chloride and phthalic anhydride, respectively, to give corresponding modified polyamides. The solubility and thermal properties were not influenced by the different DBs but were influenced by the end groups. Strong films were prepared from polyamides with lower DBs and polyamides with amino groups. [DOI 10.1295 Hyperbranched polymers have been attracting considerable attention due to their unique characteristics: branched structure, which results in low viscosity and high solubility, and their large number of end groups, which can be modified for many applications.1,2 However, most of hyperbranched polymers derived from AB 2 monomers do not afford strong films due to lack of chain entanglements, which is a necessity for the mechanical properties of engineering plastics. We have previously reported a new method for increasing chain entanglement by preparing low degree of branching hyperbranched polymers from an ABB 0 type monomer. 3On the other hand, Frey has pointed out that DB statically approached 0.5 in case of the polymerization of AB 2 monomers. 4 Most of the hyperbranched polymers reported in the literature have actually DBs close to 0.5. There have been several attempts to increase DBs: (1) polymerization of dendrons having prefabricated dendritic units; 5 (2) polymerization of AB x monomers in the presence of core molecules (Bf); 6,7 (3) enhancement of the reactivity of linear units formed during the polymerization. [8][9][10] Thompson et al. also prepared a series of hyperbranched poly(ether imide)s with different degrees of branching by changing the polymerization time from 2.5 to 20 min. 11 The changes in DB are a result of molecular rearrangements occurring via a transetherification mechanism.Generally speaking, because reaction rate constants dependent on temperature and activation energy, for an ABB 0 monomer, the relative reactivity of the B and B 0 functional group may change as changing reaction conditions (temperature or condensing agent). That is, it is possible to vary the degree of branching of polymers derived from an ABB 0 type monomer by changing the reaction conditions.In this paper, we focus on the synthesis of polyamides with different degree of branching derived from an ABB 0 type monomer by using different condensation agents. The properties and structure of the polyamides derived from different reaction conditions were investigated. The end m...

Hyperbranched poly(ether nitrile)s were prepared from a novel AB2 type monomer, 2‐chloro‐4‐(3,5‐dihydroxyphenoxy)benzonitrile, via nucleophilic aromatic substitution. Soluble and low‐viscous hyperbranched polymers with molecular weights upto 233,600 (Mw) were isolated. According to the 1H NMR and GPC data, the unique polymerization behavior was observed, which implies that the weight average molecular weight increased after the number average molecular weight reached plateau region. Model compounds were prepared to characterize the branching structure. Spectroscopic measurements of the model compounds and the resulting polymers, such as 1H, DEPT 13C NMR, and MS, strongly suggest that the ether exchange reaction and cyclization are involved in the propagation reaction. The side reactions would affect the unique polymerization behavior. The resulting polymers showed a good solubility in organic solvents similar to other hyperbranched aromatic polymers. The hydroxy‐terminated polymer was even soluble in basic water. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5835–5844, 2009

ABSTRACT:A positive-type photosensitive polyamide based on the branched polyamides with low degree of branching and 1-{1,1-bis[4-(2-diazo-1-(2H)naphthalenone-5-sulfonyloxy)phenyl]ethyl}-4-{1-[4-(2-diazo-1-(2H)naphthalenone-5-sulfonyloxy)phenyl]methylethyl}benzene (S-DNQ) as a photosensitive compound has been developed. The branched polyamides with low degree of branching having amino end groups (2a and 2b) were prepared from a ABB 0 type monomer, 4-(2,4-diaminophenoxy) benzoic acid 1 in the presence of diphenyl(2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate (DBOP) and triphenylphosphite/pyridine (TPP/Py) as a condensing agent, of which the degrees of branching (DB) were 0.10 and 0.36, respectively. Followed by end-capping with 4-hydroxy benzoic acid, endmodified polymers with phenolic hydroxy groups (4a and 4b) were successfully prepared. The polymer properties were characterized by 1 H and 13 C NMR, GPC, TG/DTA and DSC, respectively. The photosensitive polymer based on polymer 4a and 30 wt % S-DNQ showed a sensitivity of 140 mJ cm À2 and a contrast of 2.1 when it was pre-baked at 80 C for 5 min, subsequently exposed to a 436 nm light (g-line) and developed with a developer of 5 wt % aqueous tetrametylammonium hydroxide (TMAH) solution: 2-propanol (4:1 by weight ratio) at 25 C. A fine positive image of 6 mm line-and-space pattern was obtained when the film was exposed to 300 mJ cm À2 by contact-printing mode. Aromatic polyamide is well known as an important class of high-performance polymeric materials due to their high thermal stability and excellent mechanical property. The applications, however, are restricted by their poor processability due to their insolubility and high softening temperature. The key reasons for insolubility and non-melting character in aromatic polyamides are the lack of chain flexibility and strong intermolecular interactions due to high symmetry, highly polar groups and extensive hydrogen bonding. To remedy this, a great deal of efforts have been expended by introducing bulky pendant groups or flexible segment along the polymer backbone, incorporating a crank and twisted non-coplanar into the polymer backbone, and replacing symmetrical aromatic rings by unsymmetrical ones and so on.1-5 On the other hand, a strategy to utilize the abilities in dendritic macromolecules to avoid the strong chain entanglement and to introduce a variety of functional end groups is particular recent interests. Dendritic aromatic polyamides consists of dendrimer, dendron, or hyperbranched type structures possess a variety of unique properties such as good solubility, low viscosity, multivalence, and encapsulation effects, which mainly are caused by the branching and spherical architecture. In particular, hyperbranched polyamides are of great interest from a synthetic point of view because of relatively easier for rapid and large-scale synthesis compared with the dendrimers. However, producing the film with good physical properties still remains a challenge for conventional hyperbranched polymers due to the la...