Synthesis of Dendron Functionalized Core Cross-linked Star Polymers

Connal, Luke A.; Vestberg, Robert; Hawker, Craig J.; Qiao, Greg G.

doi:10.1021/ma070661h

Cited by 63 publications

(53 citation statements)

References 32 publications

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“…Divinyl benzene (DVB, 80% mixture of isomers) and ethylene glycol dimethacrylate (EGDMA, 98%) monomers were washed 3 times with 5% sodium hydroxide solution and once with distilled water, the solutions were dried over MgSO 4 , filtered and distilled from calcium hydride. 2-(2 0 -Bromo-2 0 -methylpropanoyloxy)ethyl 2,2,5-trimethyl-1,3-dioxane-5-carboxylate (1) [30] was synthesized by a previously reported procedure. 9-Anthracenecarboxylic acid (99%), 4-dimethylaminopyridine (DMAP, 99þ %), anisole (anhydrous, 99þ %), tetrahydrofuran (THF, anhydrous, 99þ %), thionyl chloride (SOCl 2 , 99þ %), and copper (I) bromide (CuBr, 98%) were used without further purification.…”

Section: Methodsmentioning

confidence: 99%

Fabrication of Reversibly Crosslinkable, 3‐Dimensionally Conformal Polymeric Microstructures

Connal¹,

Vestberg²,

Hawker³

et al. 2008

Adv Funct Materials

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Multifaceted porous materials were prepared through careful design of star polymer functionality and properties. Functionalized core crosslinked star (CCS) polymers with a low glass transition temperature (Tg) based on poly(methyl acrylate) were prepared having a multitude of hydroxyl groups at the chain ends. Modification of these chain ends with 9‐anthracene carbonyl chloride introduces the ability to reversibly photocrosslink these systems after the star polymers were self‐assembled by the breath figure technique to create porous, micro‐structured films. The properties of the low Tg CCS polymer allow for the formation of porous films on non‐planar substrates without cracking and photo‐crosslinking allows the creation of stabilized honeycomb films while also permitting a secondary level of patterning on the film, using photo‐lithographic techniques. These multifaceted porous polymer films represent a new generation of well‐defined, 3D microstructures.

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Section: Methodsmentioning

confidence: 99%

Fabrication of Reversibly Crosslinkable, 3‐Dimensionally Conformal Polymeric Microstructures

Connal¹,

Vestberg²,

Hawker³

et al. 2008

Adv Funct Materials

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“…In order to explore this approach, the so-called "arm first" synthetic strategy, Hawker and coworkers prepared dendrons as functional initiators capable of initiating polymerization by atom transfer radical polymerization (Schemes 34 to 37) [185]. The synthesis of polyester dendrons up to the fifth generation by the divergent route using 38 is described.…”

Section: 15mentioning

confidence: 99%

“…Synthesis of fifth generation dendron with initiating moiety for atom transfer radical polymerization at the focal point [185].…”

Section: 15mentioning

confidence: 99%

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Polyester Dendrimers

Twibanire

Grindley

2012

Polymers

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Polyester dendrimers have been comprehensively reviewed starting from their first synthesis in the early 1990s by Hawker and Fréchet. Polyester dendrimers have attracted and continue to attract extensive interest because they are comparatively easy to make and because, whenever they have been tested, they have been found to be non-toxic. A number of different strategies for their synthesis have been examined and the methods employed for formation of the ester bond during dendrimer assembly have been summarized. The newest approaches, including the use of bifunctional orthogonally reacting dendrons and accelerated synthesis have been surveyed.

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“…[114][115] The arm-first approach allows the synthesis of star polymers with different arm composition, but its weakness is the incomplete arm-to-star conversion. [116][117] The third method involves the gafting-onto approach through the synthesis of linear polymeric chains with terminal functionalities and subsequent binding of the chains to a multifunctional core. This approach requires synthetic reactions with high coupling efficiency, and on the contrary this methodology provides good structural control of the resulting architecture.…”

Section: Star Polymersmentioning

confidence: 99%

Synthesis of well-defined complex polymer architectures by iterative growth

Solangi¹

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The 'pursuit of precision', inspired from nature's relationship between molecular structure and physiological function, has led to the conception of complex architectures. 'Living' radical polymerization (LRP) produces polymer building block precursors with a chemical functionality on either end of a linear polymer chain, and in combination with near-quantitative 'click' reactions, provides a facile method to construct structurally diverse architectures such as cyclics, dendrimers, stars and bio/inorganic-hybrids. Building complex polymer architectures has been driven by the quest to obtain new and predictable solution and bulk properties. Incorporating sequence control into these architectures through the judicious choice of monomer or macromers will have the potential to create advanced polymer materials with unique properties and functions that are commonly found in biological systems. This will lead to material design with potential applications as adaptive materials, catalysts, and use in vaccine and drug delivery.First, a series of symmetric and asymmetric complex polymer architectures were synthesized from polystyrene PSTY building blocks. Two PSTY building blocks of similar molecular weight were synthesized using ATRP. The telechelic building block consisted of a halide group on one end and both a hydroxyl and alkyne group on the other end. These telechilic polymer chains were coupled togather by sequential growth to produce three, four or seven HO-functionalities equally spaced along the polymer backbones. The key was to maintain the halide end-group on the telechelic polymer chain during the CuAAC coupling reaction after each sequential growth. This was accomplished by using the combination of the PMDETA ligand and toluene as a solvent to produce significantly faster rates of CuAAC coupling reaction over halide abstraction. The HO-functionalities were then converted to azide groups allowing further CuAAC reactions with either alkyne polymeric dendrons or cyclics to produce equally spaced grafts along the backbone. The relative hydrodynamic volume ratios of these grafted structures to their corresponding linear analogues were lower but similar to that found from the graft (i.e. dendron or cyclic) itself. Moreover, the same relative change in the hydrodynamic volume was independent of the number of grafts, suggesting that by combining many dendrons or cyclics on a polymer backbone, the effect on the coil conformation was minimal. This methodology was further extended to produce an asymmetric block copolymer consisting of one block with two dendron grafts and the other block with two cyclic grafts.Then, a new iterative sequential growth (ISG) strategy was developed which allows the synthesis of sequence defined polymers by direct azidation of alcohols. Four low molecular weight macromers of PSTY, poly(t-butyl acrylate) P t BA, and poly(methyl acrylate) PMA were prepared by either ATRP or SET-LRP with low dispersity values and poly(ethylene glycol) PEG was obtained from a commercial source. The mac...

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Synthesis of Dendron Functionalized Core Cross-linked Star Polymers

Cited by 63 publications

References 32 publications

Fabrication of Reversibly Crosslinkable, 3‐Dimensionally Conformal Polymeric Microstructures

Fabrication of Reversibly Crosslinkable, 3‐Dimensionally Conformal Polymeric Microstructures

Polyester Dendrimers

Synthesis of well-defined complex polymer architectures by iterative growth

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