DCC/DPTS

Deprotection of 26, followed by generation growth and coupling to the triphenolic core 5 using DCC/DPTS chemistry, then gave 27. This dendritic layer-block copolymer 27 is characterized by two inner concentric layers of hydrolyzable ester-functional groups surrounded by three outer concentric layers of ether-functional groups (Scheme 10).28... 

To prepare PEG-maleimide (PEG-MI), PEG methyl ether (Me-PEG) is reacted with (XXIII) in the presence of DCC and DPTS (see Problem 12.10) in CH2CI2 solution at room temperature for 12 h. On the other hand, PMMA-maleimide (PMMA-MI) is prepared by ATRP of MMA in toluene using (XVIII) as the initiator and Cu(I)Cl/PMDETA catalyst system. After the polymerization at 40°C for 3 h, the reaction mixture is passed through a basic alumina column to remove the catalyst and precipitated into hexane to recover the polymer (PMMA-MI). 

A one-pot solution polymerization was performed at room temperature using partially aromatic monomers, namely 4,4-bis(4 -hydroxyphenyl)valeric acid as AB2 and 3-(4-hydroxyphenyl)propionic acid as AB [118] (see Table 1, entry 5 for monomer combination), in the presence of 4-(A, A dimethylamino) pyridinium 4-tosylate (DPTS) as catalyst and dicyclohexylcarbodiimide (DCC). The dependencies of the DB and the thermal properties of the polymers on the AB AB2 monomer ratio were studied. Polyesters with statistical dendritic topology, controlled DB, and > 35,000 g/mol were obtained. The DB was found to decrease with an increase in the amount of AB monomers and increasing comonomer ratio in the polymer (rp = ratio of AB to AB2) as shown in Fig. 1. Interestingly, the DB for hb homopolyester and branched copolyester at rp = 0.46 was similar (see Fig. la), because of the fact that on adding the small-sized linear AB to the more voluminous AB2 monomers in the reaction mixture, the steric effects decreased, which promoted the formation of dendritic units formed by the AB2 monomer. The thermal... 

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