Spectroscopic Investigations of Core-Based, Randomly Hyperbranched Polymers and Comparison with their Dendrimeric Counterparts

Abstract

Randomly hyperbranched polymers containing a core region are a relatively new subclass of materials. In comparison to dendrimeric polymers, there are many similarities, including their proposed applications. Because the core-based hyperbranched polymers can be prepared in a one-pot synthesis, they are an attractive alternative to the dendrimers, which require a laborious multistep process. This research is centered around the comparison of core-based, randomly hyperbranched poly(ethyleneimine) with the dendrimeric poly(propyleneimine) to better understand their host-guest properties. Two sizes of each polymer class were examined, and studies were carried out using the solvatochromic reporter molecule phenol blue. Absorbance and fluorescence measurements (emission and anisotropy) were utilized to determine the location of the fluorophore within the polymer. Results indicate that the phenol blue does associate with both the hyperbranched poly(ethyleneimine) and the dendrmeric poly(propyleneimine), although the association is not the same for the two polymer classes. The loading capacity of both polymer classes was also determined.

Spectroscopic Characterization of Core-Based Hyperbranched Poly(ethyleneimine) and Dendritic Poly(propyleneimine) as Selective Uptake Devices

“…21,[23][24][25] However, the results obtained for polymer-associated HONR indicate that this larger dye does not associate with the polymers in the same manner. For the dendritic PPI samples, absorption and fluorescence emission polarity measurements of polymer-associated HONR agree.…”

“…Moreover, all samples contain the characteristic emission profile of associated PB. 21 There is also obvious evidence of associated HONR with both the dendrimers and CBHPs, indicating that, although HONR does associate with the polymers, it does not inhibit the association of PB. As expected based on the larger size of the dye, the association of HONR with the polymers is not as strong an association as that of PB with the polymers.…”

“…There is also a slight decrease in PB fluorescence emission postextraction, indicating that, although some of the dye is removed, the association of the guest with the polymers is strong enough to withstand extraction. 21 The extraction process removed more HONR from the dendritic samples than the CBHPs; this is most likely due to the structural differences of the two polymer families. Variation in both core and branching units and the less symmetrical structure of the CBHPs potentially allows a better fit for the HONR within the CBHP branches.…”

“…21,23,24 Whereas previous work with PAMAM dendrimers utilized Nile red as an interfering agent, the low solubility of Nile red in aqueous solutions led to the use of a structural derivative, HONR.…”

Hyperbranched poly(citric acid) and its application as anticancer drug delivery system

“…Dendrimers have a wide range of applications such as drug transport,10 gene transport,11 high‐loading supports for organic synthesis,12 water purification systems,13 and molecular nanocarriers 14. However large‐scale use of dendrimers is restricted because of their labor‐intensive synthesis and the resulting limited availability in bulk quantities 15.…”