Direct synthesis of terminally “clickable” linear and hyperbranched polyesters

Abstract

1,3-Dipolar cycloaddition of an organic azide and an acetylenic unit, often referred to as the ''click reaction'', has become an important ligation tool both in the context of materials chemistry and biology. Thus, development of simple approaches to directly generate polymers that bear either an azide or an alkyne unit has gained considerable importance. We describe here a straightforward approach to directly prepare linear and hyperbranched polyesters that carry terminal propargyl groups. To achieve the former, we designed an ABtype monomer that carries a hydroxyl group and a propargyl ester, which upon self-condensation under standard transesterification conditions yielded a polyester that carries a single propargyl group at one of its chain-ends. Similarly, an AB 2 type monomer that carries one hydroxyl group and two propargyl ester groups, when polymerized under the same conditions yielded a hyperbranched polymer with numerous ''clickable'' propargyl groups at its molecular periphery. These propargyl groups can be readily clicked with different organic azides, such as benzyl azide, x-azido heptaethyleneglycol monomethylether or 9-azidomethyl anthracene. When an anthracene chromophore is clicked, the molecular weight of the linear polyester could be readily estimated using both UV-visible and fluorescence spectroscopic measurements. Furthermore, the reactive propargyl end group could also provide an opportunity to prepare block copolymers in the case of linear polyesters and to generate nanodimensional scaffolds to anchor a variety of functional units, in the case of the hyperbranched polymer. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3200-3208, 2010

Thiol‐ene clickable hyperscaffolds bearing peripheral allyl groups

“…To this end, we recently developed a novel strategy to prepare peripherally “clickable” hyperbranched polyethers in a single step using a suitably designed AB 2 type monomer that carries two propargylbenzyl ether groups and one hydroxyl group; acid‐catalyzed melt‐transetherification of this monomer yielded a hyperbranched polymer bearing a large number of peripheral propargyl groups, which could in turn be quantitatively functionalized under mild conditions via the Cu‐catalyzed click reaction with a variety of organic azides 5. Later we also showed that hyperbranched polyesters can be similarly prepared under standard melt transesterification process of a suitably designed hydroxy bis(propargyl ester) monomer 6. This was an important finding because it demonstrated for the first time that propargyl ester groups can be trans‐esterified just like any other simple methyl or ethyl esters, which are typically the basic monomers for commercial production of polyesters.…”

Synthesis and properties of networking waterborne polyurethane/silica nanocomposites by addition of poly(ester amine) dendrimer

“…It is extremely difficult to homogenize WPU matrix with silica nanoparticles just relying on the mechanical blending method. As we know, poly(ester amine) dendrimers have attracted considerable attentions because they could bring benefits of low viscosity, excellent miscibility, and highly branching molecular structures, which contain a large number of functional end groups [15–18]. All kinds of applications have been exploited for poly(ester amine) dendrimer, e.g., coating, medicine, and nanoengineering [19–21].…”

Stimulus responsive fluorescent hyperbranched polymers and their applications

“…AEE (AIE) completely surmounts the chronic barrier and may lead to more novel applications with FHBPs. For the latter, it is also an effective strategy to synthesize FHBPs for there are a large number of end groups on the periphery of the spherical shape which could considerably influence the properties [33][34][35][36][37][38][39][40]. Meanwhile, the labeled chromophores may be a helpful way to investigate some tiny changes and nano-behavior of HBPs with fluorescence.…”