Center for Advanced Macromolecular Design

Sydney, Australia

Center for Advanced Macromolecular Design

Sydney, Australia

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Ren J.M.,University of Melbourne | McKenzie T.G.,University of Melbourne | Fu Q.,University of Melbourne | Wong E.H.H.,University of Melbourne | And 7 more authors.
Chemical Reviews | Year: 2016

Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings. © 2016 American Chemical Society.


Fan K.W.,Center for Advanced Macromolecular Design | Stenzel M.H.,Center for Advanced Macromolecular Design | Granville A.M.,Center for Advanced Macromolecular Design
Journal of Materials Chemistry B | Year: 2015

5,6-Dihydroxy-1H-indazole (DHI) is able to self-polymerize through the same mussel-inspired chemistry responsible for generating poly(dopamine) (PDA), demonstrating the potential to expand this class of catecholamine-exclusive chemistry onto heterocyclic catechol derivatives for the preparation of functional materials. Although DHI exhibits slower polymerization kinetics compared to dopamine, the two chemical species are compatibly polymerizable under the same reaction conditions and allow the preparation of copolymer coatings in different molar ratios. Of these copolymers, the 1:3-copolymer (DHI-to-dopamine ratio) has demonstrated adequate structural stability as a polymer coating. While PDA performs as an intact framework, the incorporated DHI enhances the colloidal stability and provides additional coordinating functionality through the pyrazole moieties. The 1:3-copolymer was fabricated into polymer capsules which exhibit negligible cytotoxicity towards murine dermal fibroblasts (L929) and enhanced binding behaviour towards copper(ii). This represents a new channel for fabricating cargo carriers for biomedical applications that involve the use of transition metal-based species. © 2015 The Royal Society of Chemistry.


Fu C.,Tsinghua University | Fu C.,Center for Advanced Macromolecular Design | Xu J.,Center for Advanced Macromolecular Design | Tao L.,Tsinghua University | Boyer C.,Center for Advanced Macromolecular Design
ACS Macro Letters | Year: 2014

A novel and facile method, involving enzymatic monomer synthesis and a photocontrolled polymerization technique, has been successfully employed for the preparation of high-order multiblock copolymers. New acrylate monomers were synthesized via enzymatic transacylation between an activated monomer, i.e., 2,2,2-trifluoroethyl acrylate (TFEA), and various functional alcohols. These synthesized monomers were successfully polymerized without further purification via photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization under low energy blue LED light (4.8 W) in the presence of an iridium-based photoredox catalyst (fac-[Ir(ppy) 3]). In this condition, PET-RAFT allows us to achieve high monomer conversion (∼100%) with excellent integrity of the end group (>80%). Different multiblock (co)polymers, including poly(hexyl acrylate) pentablock homopolymer, poly(methyl acylate-b-ethyl acrylate-b-n-propyl acrylate-b-n-butyl acrylate-b-n-pentyl acrylate) pentablock copolymer, and poly(3-oxobutyl acrylate-b-methyl acrylate-b-3-(trimethylsilyl)prop-2-yn-1-yl acrylate) triblock copolymer containing functional groups were rapidly prepared via sequential addition of monomers without purification steps. © 2014 American Chemical Society.


Xu J.,Center for Advanced Macromolecular Design | Xu J.,Australian Center for NanoMedicine | Shanmugam S.,Center for Advanced Macromolecular Design | Fu C.,Center for Advanced Macromolecular Design | And 3 more authors.
Journal of the American Chemical Society | Year: 2016

Here, we exploit the selectivity of photoactivation of thiocarbonylthio compounds to implement two distinct organic and polymer synthetic methodologies: (1) a single unit monomer insertion (SUMI) reaction and (2) selective, controlled radical polymerization via a visible-light-mediated photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) process. In the first method, precise single unit monomer insertion into a dithiobenzoate with a high reaction yield (>97%) is reported using an organic photoredox catalyst, pheophorbide a (PheoA), under red light irradiation (γmax = 635 nm, 0.4 mW/cm2). The exceptional selectivity of PheoA toward dithiobenzoate was utilized in combination with another catalyst, zinc tetraphenylporphine (ZnTPP), for the preparation of a complex macromolecular architecture. PheoA was first employed to selectively activate a dithiobenzoate, 4-cyanopentanoic acid dithiobenzoate, for the polymerization of a methacrylate backbone under red light irradiation. Subsequently, metalloporphyrin ZnTPP was utilized to selectively activate pendant trithiocarbonate moieties for the polymerization of acrylates under green light (γmax = 530 nm, 0.6 mW/cm2) to yield well-defined graft co-polymers. © 2016 American Chemical Society.


Fu C.,Center for Advanced Macromolecular Design | Xu J.,Center for Advanced Macromolecular Design | Boyer C.,Center for Advanced Macromolecular Design
Chemical Communications | Year: 2016

A novel methodology of visible light regulated ring opening polymerization in the presence of reversible merocyanine-based photoacid was reported for the first time. In combination with a photoinduced radical polymerization technique, a dual wavelength light controlled orthogonal polymerization system was investigated to switch the polymerization between two different monomers and for the preparation of block and graft copolymers in one pot. © The Royal Society of Chemistry.


Xu J.,Center for Advanced Macromolecular Design | Shanmugam S.,Center for Advanced Macromolecular Design | Boyer C.,Center for Advanced Macromolecular Design
ACS Macro Letters | Year: 2015

In this study, we designed and synthesized novel organic single electron donor-acceptor molecules containing a free base porphyrin and a thiocarbonylthio group. The porphyrin acts as a light-harvesting antenna and donates an excited electron upon light irradiation to the electron-accepting thiocarbonylthio group. The excited electronic state of the donor-acceptor generates a radical from the thiocarbonylthio compound to activate a living radical polymerization in the presence of monomers. Thus, these donor-acceptor systems play the roles of highly efficient photoredox catalysts and radical initiators. The presence of both donor and acceptor in a single molecule enhanced the electron transfer efficiency in comparison to the donor/acceptor mixture and consequently greatly increased polymerization rates of vinyl monomers under visible light irradiation. The polymerizations mediated by these electron donor-acceptor photoredox catalysts were investigated under green (λmax = 530 nm, 0.7 mW/cm2) and red (λmax = 635 nm, 0.7 mW/cm2) lights, which exhibited great control over molecular weights, molecular weight distributions, and end-group functionalities. © 2015 American Chemical Society.


Yeow J.,Center for Advanced Macromolecular Design | Xu J.,Center for Advanced Macromolecular Design | Boyer C.,Center for Advanced Macromolecular Design
ACS Macro Letters | Year: 2015

The ruthenium-based photoredox catalyst, Ru(bpy)3Cl2, was employed to activate reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization via a photoinduced electron transfer (PET) process under visible light (λ = 460 nm, 0.7 mW/cm2). Poly(oligo(ethylene glycol) methyl ether methacrylate) was chain extended with benzyl methacrylate to afford in situ self-assembled polymeric nanoparticles with various morphologies. The effect of different intrinsic reaction parameters, such as catalyst concentration, total solids content, and cosolvent addition was investigated with respect to the formation of different nanoparticle morphologies, including spherical micelles, worm-like micelles, and vesicles. Importantly, highly pure worm-like micelles were readily isolated due to the in situ formation of highly viscous gels. Finally, "ON/OFF" control over the dispersion polymerization was demonstrated by online Fourier transform near-infrared (FTNIR) spectroscopy, allowing for temporal control over the nanoparticle morphology. © 2015 American Chemical Society.


Corrigan N.,Center for Advanced Macromolecular Design | Xu J.,Center for Advanced Macromolecular Design | Boyer C.,Center for Advanced Macromolecular Design
Macromolecules | Year: 2016

We report for the first time the use of phthalocyanine compounds, in conjunction with the common solvent N-methyl-2-pyrrolidone (NMP), as a photoinitiation system for radical polymerization under various visible and near-infrared wavelengths. A library of redox-inactive metallic phthalocyanine compounds were investigated for their ability to act as photosensitizers in these new two-component photoinitiation systems, for the radical polymerization of (meth)acrylate and (meth)acrylamide monomers. Conventional radical polymerization under these conditions was successful, and moreover, the addition of reversible addition-fragmentation chain transfer (RAFT) agents to these systems led to the production of polymers with molecular weights in agreement with theoretical predictions and molecular weight distributions typically lower than 1.15. In contrast to our previous systems described as photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) where RAFT agent is activated by the photocatalyst, we propose that the phthalocyanine compounds react via a reductive quenching pathway to oxidize NMP to an NMP radical, which can directly initiate the polymerization of monomers. © 2016 American Chemical Society.


Yeow J.,Center for Advanced Macromolecular Design | Sugita O.R.,Center for Advanced Macromolecular Design | Boyer C.,Center for Advanced Macromolecular Design
ACS Macro Letters | Year: 2016

We report the use of visible light to mediate a RAFT dispersion polymerization in the absence of external catalyst or initiator to yield nanoparticles of different morphologies according to a polymerization-induced self-assembly (PISA) mechanism. A POEGMA macro-chain transfer agent (macro-CTA) derived from a 4-cyano-4-((dodecylsulfanylthiocarbonyl)sulfanyl)pentanoic acid (CDTPA) RAFT agent can be activated under blue (460 nm, 0.7 mW/cm2) or green (530 nm, 0.7 mW/cm2) light and act simultaneously as a radical initiator, chain transfer agent, and particle stabilizer under ethanolic dispersion conditions. In particular, the formation of worm-like micelles was readily monitored by the increase of reaction viscosity during the polymerization; this method was shown to be particularly robust to different reaction parameters such as macro-CTAs of varying molecular weight. Interestingly, at high monomer conversion, different morphologies were formed depending on the wavelength of light employed, which may be due to differing degrees of polymerization control. Finally, the in situ encapsulation of the model hydrophobic drug, Nile Red, was demonstrated, suggesting applications of this facile process for the synthesis of nanoparticles for drug delivery applications. © 2016 American Chemical Society.


Xu J.,Center for Advanced Macromolecular Design | Shanmugam S.,Center for Advanced Macromolecular Design | Duong H.T.,Center for Advanced Macromolecular Design | Boyer C.,Center for Advanced Macromolecular Design
Polymer Chemistry | Year: 2015

In this article, we are investigating a series of organo-dyes, including methylene blue, fluorescein, rhodamine 6G, Nile red and eosin Y, to perform a visible light-mediated controlled/"living" radical polymerization of methacrylates. We demonstrate that eosin Y and fluorescein were efficient catalysts to activate a photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) mechanism. The concentration of eosin Y was varied from 10 to 100 ppm with respect to monomers. This polymerization technique yielded well-defined (co)polymers with a good control of the molecular weights ranging from 10 000 to 100 000 g mol-1 and low polydispersities (PDI < 1.30). A variety of functional monomers, including N,N-dimethylaminoethyl methacrylate, hydroxyl ethyl methacrylate, pentafluorophenyl methacrylate, glycidyl methacrylate, oligoethylene glycol methyl ether methacrylate (OEGMA), and methacrylic acid, were successfully polymerized. Finally, the addition of a tertiary amine, such as triethylamine, afforded the polymerization in the presence of air via a reductive quenching cycle. Different diblock polymethacrylate copolymers, i.e. PMMA-b-POEGMA and PMMA-b-PMMA, were prepared to demonstrate the high end group fidelity. This journal is © The Royal Society of Chemistry.

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