Hyperbranched polyamides synthesis

Chao D, He L, Berda EB, Wang S, Jia X, Wang C (2013) Multifunctional hyperbranched polyamide synthesis and properties. Polymer 54 3223-3229... 

Shabbir S, Zulfiqar S, Sarwar Ml (2011) Amine-teuminated aromatic and semi-aromatic hyperbranched polyamides synthesis and characterizatitHi. J Polym Res 18 1919—1929... 

The solid-phase synthesis of dendritic polyamides was explored by Frechet et al. [49]. Inspired by the technique used by Merrifield for peptide synthesis, the same strategy was used to build hyperbranched polyamides onto a polymeric support. The idea was to ensure the preservation of the focal point and to ease the purification between successive steps. The resulting polymers were cleaved from the solid support, allowing ordinary polymer characterization. The reaction was found to be extremely sluggish beyond the fourth generation. 

Nasar, A. S., Jikei, M., Kakimoto, M.aki. (2003). Synthesis and properties of polyurethane elastomers crosslinked with amine-terminated AB2-type hyperbranched polyamides, Eur. Pnlvm. 1. 39,1201-1208. 

Ohta Y, Fuji S, Yokoyama A, Furuyama T, Uchiyama M, Yokozawa T (2009) Synthesis of well-defined hyperbranched polyamides by condensation polymerization of AB2 monraner through changed substituent effects. Angew Chem Int Ed 48 5942—5945... 

To the best of our knowledge, only one other example of a carboxylic acid functionalized hyperbranched structure is known in the literature, and this concerns a polyamide [19]. The synthesis reported starts from A2 (aminofunctional) and B3 (carboxylic acid functional) units and leads to low molecular weight products due to low conversion in dilute solution. These conditions were mandatory to prevent gelation [20]. Two different approaches to the synthesis of carboxylic acid functional hyperbranched polyesteramides are presented below [21]. 

A wide range of other monomer units have been employed in the synthesis of hyperbranched macromolecules and the range of structures obtained is nearly as diverse as those for dendritic macromolecules. For example, hyperbranched polyphenylenes [93], polyesters [104, 107-109], polyethers [110-112], polyamides [113], polysilanes [114], polyetherketones [100], polycarbazoles [115], etc. [116-118] have been prepared. Interestingly, a number of groups have also used growth processes other than condensation chemistry to prepare hyper-... 

Hyperbranched polymers are formed by polymerization of AB,-monomers as first theoretically discussed by Flory. A wide variety of hyperbranched polymer structures such as aromatic polyethers and polyesters, aliphatic polyesters. polyphenylenes, and aromatic polyamides have been described in the literature. The structure of hyperbranched polymers allows some defects, i.e. the degree of branching (DB) is less than one. The synthesis of hyperbranched polymers can often be simplified compared to the one of dendrimers since it is not necessary to use protection/deprotection steps. The most common synthetic route follows a one-pot procedure " where AB,-monomers are condensated in the presence of a catalyst. Another method using a core molecule and an AB,-monomer has been described. ... 

Y. Ishida, A. C. F. Sun, M. Jikei and M. Kakimoto, Synthesis of hyperbranched aromatic polyamides starting from dendrons as monomers Effect of monomer multiplicity on the degree of branching , Macromolecules, 2000, 33, 2832-8. 

G. Yang, M. Jikei, M. Kakimoto, Synthesis and properties of hyperbranched aromatic polyamide. Macromolecules, 32, 2215-2220 (1999). 

Froehling, P. E. Dendrimers and dyes-a review. Dyes and pigments, 48, 187-195 (2001). Jikei, M., Fujii. K., and Kakimoto, M. Synthesis and characterization of hyperbranched aromatic polyamide copolymers prepared from AB and AB monomers. Macromol. Symp., 2003,199,223-232 (2001). 

R. Mahmoodi, T. Dodel, T. Moieni, and M. Hasanzadeh, Synthesis and Application of Amine-Terminated AB2-Type Hyperbranched Polymer to Polyamide-6 Fabrics , Polymers Research Journal, 7, 00, (2013). 

Scheme 21 Synthesis of linear-hyperbranched diblock polyamides...

Jikei M, Chon SH, Kakimoto MA, Kawauchi S, Imase T, Watanebe J (1999) Synthesis of hyperbranched aromatic polyamide from aromatic diamines and tiimesic acid. Macnnnole-... 

Liou GS, Lin HY, Yen HJ (2009) Synthesis and characterization of electroactive hyperbranched aromatic polyamides based on A2B-type triphenylamine moieties. Mater Chem 19 7666-7673... 

It was,and still is, a purpose of our work to illustrate the synthetic potential of "a-b monomers" in the field of aromatic polyethers, polyesters and polyamides (concentrating on polyesters in the present contribution). The preparation of star-shaped and hyperbranched polycondensates is plagued by side-reactions resulting in crosslinks, and thus, clean step-growth processes are a basic requirement for a successfid synthesis. In this connection the potential of silicon mediated polycondensations should be explored, because polycondensations of silylated monomers may be a cleaner process than that of the corresponding nonsilylated (protonated) monomers, for instance, because proton catalyzed side reactions, such as the Fries-rear-rangement, are avoided. 

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