Terminal units, hyperbranched polymer characterization

Hyperbranched polymers are characterized by their degree of branching (DB). Hie DB of polymers obtained by the step-growth polymerization of AB2-type monomers is defined by Eq. (2.1) in which dendritic units have two reacted B-groups, linear units have one reacted B-group, and terminal units have two unreacted B-groups191 ... 

A hyperbranched polymer is often characterized by the degree of branching DB [Holter et al., 1997 Jo and Lee, 2001 Kim, 1998 Lee et al., 2000]. For the hyperbranched polymer produced from AB2, there are three different types of repeat units dendritic, linear, and terminal units defined as units having two, one, and no B groups reacted, respectively. The degree (fraction) of branching (DB) is given by... 

A closer investigation of the hyperbranched base polyester reveals that the repeating unit can be incorporated in three different ways in the polymer skeleton, assuming that no side reactions occur. The terminal units all have both their hydroxyl groups left unreacted (C), while bis-MPA in interior layers are either fully branched or linearly incorporated (B) (Figure 8). These linearly incorporated building blocks do not exist in a dendrimer. In order to mimic these differently incorporated building blocks, low molar mass model compounds were synthesized and characterized with C-NMR (Table 5). The base polyesters were subsequently... 

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