Recent advances in the fine topology regulation of hyperbranched polymers from an A2 + B3 strategy were presented from the perspectives of topology description and architecture control.

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The attention network test (ANT) is a reliable tool to detect the efficiency of alerting, orienting, and executive control networks. However, studies using the ANT obtained inconsistent relationships between attention networks due to two reasons: on the one hand, the inter-network relationships of attention subsystems were far from clear; on the other hand, ANT scores in previous studies were disturbed by possible inter-network interactions. Here we proposed a new computing method by dissecting cue-target conditions to estimate ANT scores and relationships between attention networks as pure as possible. The method was tested in 36 participants. Comparing to the original method, the new method showed a larger alerting score and a smaller executive control score, and revealed interactions between alerting and executive control and between orienting and executive control. More interestingly, the new method revealed unidirectional influences from alerting to executive control and from executive control to orienting. These findings provided useful information for better understanding attention networks and their relationships in the ANT. Finally, the relationships of attention networks should be considered with more experimental paradigms and techniques.

In this contribution, we report a convenient expression of average number of cyclic structures (ANC) and cyclic-average molecular weight (M C ) to quantificationally describe the topological defect of intramolecular cyclization in highly branched polymers synthesized via A 2 + B n (n ≥ 3) stepwise polymerization strategy by a combination of nuclear magnetic resonance spectrometry (NMR) and size exclusion chromatography (SEC). The ANC and M C depend on the number ratio of dendritic, linear, terminal units and numberaverage molecular weight of hyperbranched polymers, which can be derived from NMR and SEC, respectively. The analysis of hyperbranched polycarbosilanes with silicon hydrogen bonds (A) or vinyl groups (B) termini from A 2 + B 3 approach indicates that the quantificational description of ANC and MC make it easy to well understand intramolecular cyclic structures resulting in a highly branched topology. Regulating the flexibility and rigidness of internal units in A 2 monomers is an effective way to control the extent of intramolecular cyclization. Because of the general and convenient nature, the ANC and M C have potential for the quantificational description of intramolecular cyclization, i.e. one type of topological defect, in a variety of hyperbranched polymers synthesized via A 2 + B n strategy.

Terminal index (TI) was presented as a new characteristic parameter for quantitative description of branched and cyclic topology of highly branched soluble polymers derived from A2 + B3 stepwise polymerization. TI is defined as the ratio of terminal units of an A2 + B3 type highly branched polymer to those in its perfect hyperbranched counterpart. TI is concisely represented as T/(D + L), which can be conveniently calculated from a quantitative NMR spectrum. The model of soluble A2 + B3 type polymers is suggested as an intermediate between multicyclic polymers and perfect hyperbranched polymers. The TI ranges between 0 and 1 where a higher TI indicates a perfect hyperbranched topology while a low TI indicates a multicyclic structure. The analysis of soluble A2 + B3 type polyesters and polycarbosilanes as model polymers demonstrates that TI as a more precise parameter, along with degree of branching, can be generally applied to understand the fine topology of highly branched polymers derived from A2 + B3 polymerization.