New synthetic methods for the formation of basic, polyvalent, hyperbranched grafts

Abstract

A practical synthetic route to polybasic, polyamine, hyperbranched grafts using commercially available polyethyleneimine (PEI) and cyanuric chloride as a coupling agent is described. The grafting process was followed by XPS spectroscopy, TGA analysis, ATR‐IR spectroscopy, acid–base titration, and by 13C CP‐MAS NMR spectroscopy. In the case of silica gel, thermal gravimetric analyses showed that a 35 wt % loading of graft could be obtained. Acid–base titration of hyperbranched PEI grafts on silica gel and oxidized polyethylene powder showed the ion‐exchange capacities of these PEI‐grafted substrates were 1.00 and 0.17 mmol of base/g of solid, respectively. Although the focus of the paper is on grafting on silica gel, the influence of the kind of support and solvent on the grafting process and the ion‐exchange capacity was examined. Water was a good solvent for PEI grafting onto silica gel, but a more hydrophobic polyethylene support required the use of dichloromethane as a solvent for PEI graft synthesis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4654–4665. 2005

Two Decades of Triazine Dendrimers

“…While our 20 years of triazine dendrimer chemistry have been reviewed in the past [ 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ], this review is the first attempt to catalogue our entire effort. With the exception of the methodology developed for installing NH 2 groups on triazines with benzylated amines [ 78 ], the use of cyanuric chloride to generate hyperbranched PPI [ 79 ], the use of these materials as objects for light-driven transportation [ 80 ], and their use as a lens to view mechanistic organic chemistry [ 81 ], this effort summarizes the entirety of our body of work, which was performed by a host of talented coworkers and collaborators from my time at Texas A&M University and concluding at Texas Christian University. Throughout, we looked to the community for lessons learned and inspiration.…”

Covalent Layer‐by‐Layer Assembly Using Reactive Polymers

“…Amine-functionalized polymers and small molecules have also been used in combination with reactive building blocks bearing isocyanate [81,82], dichlorophosphazene [83], acrylate [84][85][86]147], alkyl halide [87,88], epoxide [89], or aldehyde groups [90][91][92][93][94][95][96][97][98] to fabricate covalent LbL films cross-linked with urea [81,82], phosphazene [83], amino-ester [84][85][86]147], alkyl amine [84][85][86][87][88], or Schiff base [90][91][92][93][94][95][96][97][98] (imine) linkages. Approaches based on reactions between amine-and aldehyde-functionalized components (to form imine or Schiff base linkages) have been particularly well studied because of the relatively fast and mild (aqueous) nature of these reactions, which also permits reactive immobilization of biomacromolecular agents such as proteins into cross-linked multilayers.…”

Covalent layer-by-layer assembly—an effective, forgiving way to construct functional robust ultrathin films and nanocomposites

“…The Bergbreiter and Simanek groups reported using nucleophilic aromatic substitution of PEI (4) and cyanuric chloride (12) as a route to LbL covalent grafts on silica. 42 Water, instead of organic solvents, can be used as a solvent for the PEI-grafting in this case. The stepby-step process shows a trend of linear growth based on acid--base titration of the free amine groups of the PEI-grafts.…”