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Poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) (PEG-PLGA) block copolymers and their thermoresponsive hydrogels have been widely studied as injectable depots for the sustained release of therapeutics. The thermogelling temperatures of PEG-PLGA copolymer solutions and the properties of their corresponding hydrogels are highly sensitive to the polymer microstructure. Often, it can be difficult to precisely control the microstructure because of transesterification side reactions that occur during ring-opening polymerisation (ROP) of lactide (L) and glycolide (G) monomers under various conditions. Therefore, we undertook a detailed study to understand how different reaction conditions influenced the reaction kinetics, monomer sequence and side reactions for the synthesis of a PLGA-PEG-PLGA triblock copolymer. ROP was conducted under thermal control (100, 110 and 120 degrees C) or in the presence of the catalysts tin(ii) 2-ethylhexanoate (Sn(Oct)(2)) and tin(ii) trifluoromethanesulfonate (Sn(OTf)(2)) at various catalyst loadings. The reactions were monitored via proton nuclear magnetic resonance (H-1 NMR) spectroscopy, gel permeation chromatography (GPC) and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI ToF MS). While ROP proceeded faster with catalysts than the uncatalysed reaction at an equivalent temperature, the onset of side reactions typically occurred at much lower monomer conversions and to a greater extent, resulting in a plateau in the molecular weight and broadening of the molecular weight distribution. For Sn(Oct)(2) catalysed ROP, an increase in the catalyst loading had negligible effect on the occurrence or extent of side reactions, but led to a surprising increase in the rate of polymerisation of L relative to G. Sn(OTf)(2) catalysed ROP resulted in significant side reactions from the start of the polymerisation. These results provide insights into the influence of polymerisation conditions on the microstructure of PLGA-PEG-PLGA triblock copolymers that may prove useful for their improved and controlled synthesis. Refereed/Peer-reviewed

Ligation chemistries are often required to perform under stringent conditions that preserve the integrity and function of (bio)conjugates, including specific biological buffers. To explore the versatility of the pentafulvene-maleimide ligation for (bio)conjugations, we studied the stability of the coupling partners and their Diels-Alder cycloaddition (DAC) in buffers used commonly in biological assays, protein chemistry and bioconjugates. The stability of 6,6-dialkylpentafulvene and maleimide derivatives to a panel of buffers with pH values between 3.7 and 10.1 was monitored via(1)H NMR spectroscopy. While the pentafulvene displayed excellent stability, hydrolysis of the maleimide was observed in several cases, although the extent of hydrolysis did not correlate with pH. For almost all buffers the pentafulvene-maleimide DAC proceeded efficiently and at a significantly faster rate than maleimide hydrolysis under the conditions studied. The buffer composition nor pH appeared to have a significant effect on the kinetics of the DAC with second-order rate constants (k(2)) ranging from 0.14 to 0.33 M-1 s(-1) (23 +/- 1 degrees C). This study highlights the versatility of the pentafulvene-maleimide ligation to proceed under a wide range of conditions relevant for (bio)conjugations and that maleimide hydrolysis in aqueous system may be promoted or inhibited by certain buffers. Refereed/Peer-reviewed

A facile, highly efficient, and metal-free synthesis of well-defined polyester-based core cross-linked star (CCS) polymers with yields of up to 96 % was achieved via an organic catalyst (i.e., methanesulfonic acid) mediated ring-opening polymerization (ROP) at room temperature, through either a two-pot or a one-pot, two-step strategy. CCS polymers with narrow molecular weight distributions (PDI ≤ 1.3) and macroinitiator (MI) conversions of 90−96% were prepared using poly(ε- caprolactone) (PCL) MIs with molecular weights ranging from 9.9 to 36.2 kDa and [4,4′-bioxepane]-7,7′-dione (BOD) as the cross-linker. Furthermore, transesterification was identified as being responsible for the small percentage of unincorporated low molecular weight polymer remaining and star−star couplings in the star formation. Compared to CCS polymers synthesized via the methanesulfonic acidmediated ROP, CCS polymers prepared via ROP mediated by high transesterification rate catalysts (i.e., stannous octoate (Sn(Oct)2)) suffer from much lower star purity (ca. 70%) and star−star coupled products due to more prominent transesterification side-reactions. Refereed/Peer-reviewed

Injectable hydrogels are promising materials for the sustained delivery of therapeutics, bioactives and cell therapies. Hydrogels that display suitable processing times and rapid gelling kinetics upon injection are particularly desirable as they can limit burst release of their payload. Therefore, we aimed to develop hydrogels that could be readily processed at ambient temperature, gelled rapidly at physiological temperature, and possessed tuneable properties (e.g., degradation and release profiles). To achieve this, a unique dual cross-linking mechanism was investigated, employing a combination of pentafulvene-maleimide Diels-Alder cycloaddition (DAC) chemistry and thermoresponsive physical cross-linking with a functionalised poly(ethylene glycol -b -propylene glycol -b-ethylene glycol) (PEG-PPG-PEG; Pluronic F-127) copolymer. A combination of temperature dependent nuclear magnetic resonance spectroscopy, dynamic light scattering, and rheological measurements were conducted to interrogate the gelation mechanism. Whereas the reaction between aqueous solutions of maleimide functionalised Pluronic and pentafulvene functionalised PEG star polymer resulted in hydrogels with gelation times (tgel) between 30 and 55 mins at ambient temperature, significantly faster tgel values (5-10 mins) were observed at physiological temperatures (37 degrees C). The relatively slow gelation at ambient temperature provided good working times and injectability through narrow gauge (261/2 G) needles. While the initial Young's modulus (E) of the hydrogels was highly dependent on the gelation temperature, the E remained dynamic in response to further temperature changes post-gelation. The hydrogels displayed relatively low swelling (20-30% mass increases) and degradation times (td) up to 16 d, which provided for the sustained release of latex particles (cell mimic) over a period of 7-14 d. With their tuneable gelation kinetics and properties, the thermoresponsive DAC hydrogels have potential for the controlled release of therapeutics. Refereed/Peer-reviewed

Refereed/Peer-reviewed Introduced predators are a significant threat to global biodiversity and are responsible for most of all modern bird, reptile, and mammal extinctions. In Australia, the introduced feral cat (Felis catus) kills 459 million mammals annually and leaves many species facing extinction. Attempted reintroductions of threatened mammal species often fail due to the persistence of intractable feral cats termed "problem individuals" and the swift depredation of the reintroduced population. Biomaterial implants could hold the key to targeting problem individuals. Herein, we report the development of the population-protecting implant, a subcutaneous implant for native mammals. The implant is intended to be inert within the subcutaneous environment for the life of the native mammal and to release a toxic payload in the gastric environment of a feral cat when ingested during a predation event. By toxifying and causing the death of the feral cat, the problem individual is eliminated, and the remaining population of native mammals is protected from further predation. To achieve this, an innovative reverse enteric coating was developed for use as a biomaterial, which exhibited a previously unreported level of pH selectivity for solubility at gastric pH. Large batches of implants were manufactured via fluidized-bed spray coating with a uniform reverse enteric coating and low intrabatch variability. Implants with a 300 μm coating afforded significant stability and retention of the payload at subcutaneous pH in vitro, with rapid release of the payload observed at gastric pH. In addition, implants exhibited favorable stability in vivo in rats, with no observed difference in biocompatibility compared to conventional radio-frequency identification microchips. This work demonstrates a proof of concept of an innovative type of implant and serves as the basis for its future development and translation into the field.

This paper presents recycling of selective laser sintering (SLS) waste nylon into printable filaments and parts reinforced with Mg particles. Waste nylon and waste–Mg powder mixture with 2%, 4%, and 8% Mg to nylon were extruded into the filaments. Moisture absorption, differential scanning calorimetry, and melt flow index experiments were conducted to determine the thermal characteristics, while tensile and flexural tests were conducted to evaluate mechanical properties and failure mechanisms. The results were compared with off-the-self (OTS) nylon. Waste powder was found to be extrudable and printable as FFF filament. Waste filament diameter closely matched standard filament size, while exhibiting reduced moisture absorption. High melting and crystallisation temperature for the waste nylon demonstrated a degradation of the plastic during the SLS process. Young’s modulus and ultimate tensile strength for the waste filament increased by 1.6-fold compared to that for OTS, while Mg-composite filament surpassed the waste and OTS. Waste and Mg composite dog bone results showed an increase in strength and stiffness, but the ductility deteriorated. Both flexural strength and modulus for the waste nylon increased by 13% and 26%, respectively, over OTS, and the addition of Mg enhanced flexural strength by up to 5-fold at 8% Mg over the waste. Printed surface topography demonstrated that the waste and Mg composite filaments can print the parts with desired geometric shapes and acceptable surface texture. The findings showed that recycling waste SLS powder into FFF prints would be a viable and useful alternative to disposal, given its abundance Refereed/Peer-reviewed

Refereed/Peer-reviewed The applications of bioconjugation chemistry are rapidly expanding, and the addition of new strategies to the bioconjugation and ligation toolbox will further advance progress in this field. Herein, we present a detailed study of the Diels–Alder cycloaddition (DAC) reaction between pentafulvenes and maleimides in aqueous solutions and investigate the reaction as an emerging bioconjugation strategy. The DAC reactions were found to proceed efficiently, quantitatively yielding cycloadducts with reaction rates ranging up to ∼0.7 M–1 s–1 for a series of maleimides, including maleimide-derivatized peptides and proteins. The absence of cross-reactivity of the pentafulvene with a large panel of functional (bio)molecules and biological media further demonstrated the bioorthogonality of this approach. The utility of the DAC reaction for bioorthogonal bioconjugation applications was further demonstrated in the presence of biological media and proteins, as well as through protein derivatization and labeling, which was comparable to the widely employed sulfhydryl–maleimide coupling chemistry.

Amino end-group functionalised polyglycols are important intermediates in the synthesis of sophisticated polymeric architectures and biomaterials. Herein, we report a facile strategy for the end-group conversion of hydroxyl-terminated polyglycols to amino-terminated polyglycols in high isolated yields and with excellent end-group fidelity. Following traditional conversion of polyglycol hydroxyl end-groups to azides via the corresponding mesylate, reduction with zinc in the presence of ammonium chloride afforded a range of amino end-group functionalised poly(ethylene glycol) and poly(propylene glycol) homopolymers and copolymers with isolated yields of 82–99% and end-group conversions of >99% as determined by NMR spectroscopy and MALDI ToF MS. Furthermore, this process is applicable to a sequential reagent addition approach without intermediate polymer isolation steps with only a slight reduction in yield and end-group conversion (95%). Importantly, a simple work-up procedure provides access to high purity polyglycols without contamination from other reagents. Refereed/Peer-reviewed

Thermoresponsive polymers have been used extensively for various applications including food additives,pharmaceutical formulations, therapeutic delivery, cosmetics and environmental remediation, to mention a few. Many thermoresponsive polymers have the ability to form physical hydrogel networks in response to temperature changes, which are particularly useful for emerging biomedical applications, including cell therapies,drug delivery systems, tissue engineering, wound healing and 3D bioprinting. In particular, the use of polysaccharides with thermoresponsive properties has been of interest due to their wide availability, versatile functionality, biodegradability, and in many cases, inherent biocompatibility. Naturally thermoresponsive polysaccharides include agarose, carrageenans and gellan gum, which exhibit upper critical solution temperatures,transitioning from a solution to a gel state upon cooling. Arguably, this limits their use in biomedical applications, particularly for cell encapsulation as they require raised temperatures to maintain a solution state that may be detrimental to living systems. Conversely, significant progress has been made over recent years to develop synthetically modified polysaccharides, which tend to exhibit lower critical solution temperatures,transitioning from a solution to a gel state upon warming. Of particular interest are thermoresponsive polysaccharides with a lower critical solution temperature in between room temperature and physiological temperature,as their solutions can conveniently be manipulated at room temperature before gelling upon warming to physiological temperature, which makes them ideal candidates for many biological applications. Therefore,this review provides an introduction to the different types of thermoresponsive polysaccharides that have been developed, their resulting hydrogels and properties, and the exciting applications that have emerged as a result of these properties. Refereed/Peer-reviewed

The unusual electronic properties and unique reactivity of fulvenes have interested researchers for over a century. The propensity to form dipolar structures at relatively low temperatures and to participate as various components in cycloaddition reactions, often highly selectively, makes them ideal for the synthesis of complex polycyclic carbon scaffolds. As a result, fulvene cycloaddition chemistry has been employed extensively for the synthesis of natural products. More recently, fulvene cycloaddition chemistry has also found application to other areas including materials chemistry and dynamic combinatorial chemistry. This highlight article discusses the unusual properties of fulvenes and their varied cycloaddition chemistry, focussing on applications in organic and natural synthesis, dynamic combinatorial chemistry and materials chemistry, including dynamers, hydrogels and charge transfer complexes. Tables providing comprehensive directories of fulvene cycloaddition chemistry are provided, including fulvene intramolecular and intermolecular cycloadditions complete with reactant partners and their resulting cyclic adducts, which provide a useful reference source for synthetic chemists working with fulvenes and complex polycyclic scaffolds Refereed/Peer-reviewed

Polysaccharides have been used widely in many industries, from food technology and mining to cosmetics and biomedical applications. Over recent years there has been growing interest in the development of responsive polysaccharides with unique and switchable properties, particularly systems that display lower-critical solution temperatures (LCSTs). Therefore, in this study we aimed to investigate a novel strategy that would allow the conversion of non-responsive polysaccharides into thermoresponsive polysaccharides with tuneable LCSTs. Through the functionalisation of dextran with alkylamide groups (isopropyl amide, diethyl amide, piperidinyl and diisobutyl amide) using a carbodiimide coupling approach in conjunction with amic acid derivatives, we prepared a library of novel dextrans with various degrees of substitution (DS), which were characterised via nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The alkylamide-functionalised dextrans were found to have good solubility in aqueous solutions, with the exception of those having a high DS of large hydrophobic substituents. Determination of the thermoresponsive characteristics of the polymer solutions via UV–vis spectroscopy revealed that the LCST of the alkylamide-functionalised dextrans was highly dependent on the type of alkylamide group and the DS and could be tuned over a large range (5–35 °C). Above the LCST, all of the thermoresponsive alkylamide-functionalised dextrans formed colloidal dispersions with particles sizes ranging from 400 -600 nm, as determined by dynamic light scattering (DLS). In addition, the polymers were found to exhibit a fast and reversible phase transition in solution with narrow hysteresis (∼ 1–5 °C). Finally, the injectability and biocompatibility of the novel thermoresponsive dextrans was confirmed in vivo via subcutaneous and intracranial ventricle injections, with no local or systemic toxicity noted over a 14 d period. Overall, the alkylamide-functionalised dextrans display interesting thermoresponsive properties and trends that may make them useful in biomedical applications, such as drug-delivery. Refereed/Peer-reviewed

We report the synthesis of a well-defined molecular bottlebrush polymer with stereoregular side chains (i.e., syndiotactic PMMA). The simultaneous control over the molecular weight, side-chain tacticity, and architecture allows the macromolecule to stereocomplex with the complementary linear stereoregular polymers (i.e., isotactic PMMAs) in controlled manners. By modulating the feed ratio of the complexing materials and chain length of the linear assembling component, a variety of crystalline materials with different sizes and morphologies, including discrete spherical nanoparticle, multiple-particle assembly, and cross-linked network structure, can be produced. Among these, uniformed sized, stable nanocrystals that exhibit temperature-induced solution assembly and disassembly properties can be derived from a combined process of PMMA triple-helix stereocomplex formation and polymer architecture-directed intramolecular crystallization. This work has established a new, facile synthetic protocol toward stimuli-responsive organic nanocrystals, which is applicable to the fabrication of a wide variety of functional crystal nanomaterials with practical applications. Refereed/Peer-reviewed

Cyclodextrin-based supramolecular assemblies derived from poly(dimethylsiloxane) (PDMS) functionalized polyrotaxanes (PRXs) were self-assembled into core-shell morphologies and used as soft nanoparticle (SNP) additives in the selective layer of thin film composite (TFC) membranes for the first time. Various weight percentages (wt%) of the PRX SNP additives were combined with Pebax® 2533 to form the selective layer, and the gas transport properties of the TFC membranes were studied in detail. Increasing the amount of PRX SNP additives led to a significant increase in CO2 permeance of the membranes, with only a slight decrease in the CO2/N2 selectivity, which was attributed to the dynamic nature (i.e., translational and rotational freedom) of the conjugated PDMS chains on the PRXs. In comparison, the performance of membranes prepared using a conventional analogue with fixed PDMS chains was inferior. The excellent gas transport properties observed for membranes are attributed to the novel self-assembly process of the dynamic PRX SNP additives; the sliding nature of the conjugated PDMS chains allow for increased exposure of the CO2-philic PEG backbone and increased size of the hydrophobic core leading to improved membrane selectivity and permeability. The effect of varying operating conditions (feed pressure and temperature) was also investigated and compared between the dynamic and fixed additive systems. Interesting trends were observed with the dynamic PRX system which diverges from conventional systems. This study opens up new avenues for CD-based supramolecular chemistry in the field of membrane technologies for gas separation. Refereed/Peer-reviewed

Antifogging and frost-resistant coatings can be used in a wide range of applications and enable high light transmission through substrates even under changes in environmental conditions. In this study, surface confined and cross-linked antifogging thin films are fabricated on glass slides via catalyst induced cross-linking (CIC), which has been recently introduced as an easy and efficient cross-linking methodology. Four different poly(ethylene glycol) (PEG)-based polymers with different hydrophilicity are synthesized and used to prepare films via CIC. Films prepared from the most hydrophilic PEG-based polymers display the best antifogging performances when exposed to a temperature change from -20 to 22 °C. Furthermore, several parameters including cross-linking density, surface roughness, hydrophobicity, and exposure time are also evaluated in terms of film transparency. Through these measurements, it is determined that, more loosely cross-linked films retain antifogging ability for longer time periods due to higher film swellability as compared to, more highly cross-linked films. This study signifies the crucial role of the film cross-linking density and hydrophilicity on the antifogging function. Refereed/Peer-reviewed

Current organ transplantation protocols require the rapid transport of freshly isolated donor tissue to the recipient patient at the site where the procedure is to be conducted. During transport, the tissue graft can quickly deteriorate as a result of oxygen starvation. In this study, we report the fabrication of oxygen-releasing coatings for improved tissue preservation. The coatings were prepared via the encapsulation of calcium peroxide or urea peroxide microparticles between layers of octadiene plasma polymer films. By varying the thickness of the plasma polymer coating and type of peroxide, formulations were obtained that generate oxygen upon contact with aqueous solutions, while at the same time limiting the amount of toxic reactive oxygen species produced. The optimized coatings were tested under hypoxic conditions using the MIN6 β-cell line, which resulted in a 3-fold increase in the viability of cultured cells. These thin oxygen-releasing coatings can be deposited on a wide range of surfaces, creating a platform for oxygen delivery with the potential to extend the viability of transported tissues and increase the time frame available for graft transport. Refereed/Peer-reviewed

The application of cyclodextrin (CD)-based host-guest interactions towards the fabrication of functional supramolecular assemblies and hydrogels is of particular interest in the field of biomedicine. However, as of late they have found new applications as advanced functional materials (e.g., actuators and self-healing materials), which have renewed interest across a wide range of fields. Advanced supramolecular materials synthesized using this noncovalent interaction, exhibit specificity and reversibility, which can be used to impart reversible cross-linking, specific binding sites, and functionality. In this review, various functional CD-based supramolecular assemblies and hydrogels will be outlined with the focus on recent advances. In addition, an outlook will be provided on the direction of this rapidly developing field. Refereed/Peer-reviewed

The continuous assembly of polymers (CAP) mediated via ring-opening metathesis polymerization (ROMP) is demonstrated as a simple and versatile method to fabricate tailored nanostructured thin films. The film thickness and topography were highly dependent upon the variation of different factors that influence the ROMP reaction and mechanism of the assembly process. Herein, we present a detailed investigation of the influence of various parameters on the rate of film formation, the film thickness and the film topography. Whereas the macrocross-linker concentration and molecular weight determined the final film thickness and surface coverage, the initiator concentration and ROMP catalyst activity were found to have a negligible effect on the film properties. Importantly, the minimum amount of polymerizable moieties required in the macrocross-linker to obtain fine control over film thickness and high surface coverage was found to be 7 mol%. The addition of excess ligand (#100 mM) for the catalyst increased the catalyst lifetime leading to thicker films, although further increases (>100 mM) were found to retard the metathesis reaction. These findings provide valuable insights into the CAPROMP process and will contribute toward developing the next generation of CAP ultrathin films for advanced applications. Refereed/Peer-reviewed

A series of novel brush triblock copolymers containing ‘glassy’ fluorinated polyimide, poly((4,4′-hexafluoroisopropylidene diphthalic anhydride)- co -(2,3,5,6-tetramethyl-1,4-phenylenediamine)) (poly(6FDA- co -TMPD)), and ‘rubbery’ polydimethylsiloxane monomethacrylate (PDMS-MA) were synthesized and characterized. Well-defined difunctional poly(6FDA- co -TMPD) with α,ω-amino end-groups was initially prepared via step-growth polymerization using precise control of the diamine (TMPD) to dianhydride (6FDA) ratio. Subsequent functionalization with 2-bromo iso butyryl bromide afforded a telechelic macroinitiator suitable for atom transfer radical polymerization (ATRP). The macroinitiator and its diamino poly(6FDA- co -TMPD) precursor were characterized via gel permeation chromatography (GPC), 1 H nuclear magnetic resonance (NMR) spectroscopic analysis and matrix assisted laser desorption ionization time-of-flight (MALDI ToF) mass spectroscopy. ATRP of PDMS-MA using the macroinitiator in different molar ratios afforded a series of brush triblock copolymers with high monomer conversions (88–94%) and varying PDMS weight fractions. Self-assembly of the triblock brush copolymers in dimethylformamide (DMF) afforded nanoparticles with hydrodynamic diameters ( d H ) ranging from 87 to 109 nm, as determined by dynamic light scattering (DLS) analysis. Cross-linking of the nanoparticles was achieved via hydrogen abstraction through the thermal degradation of benzoyl peroxide. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) revealed that the self-assemblies and their cross-linked derivatives had spherical morphologies.

A new top-down approach to generate stable nanoscale films via catalyst induced cross-linking (CIC) is demonstrated. Polymers with various compositions and bearing pendent norbornene groups (defined as macrocross-linkers) are initially spin-coated onto substrates to form nanometre-thick films; when the films are brought into contact with a catalyst solution, ring-opening metathesis polymerization (ROMP)-mediated cross-linking efficiently occurs to lock the film into place. CIC provides a new paradigm for the fabrication of stable nanoscale films and provides an alternative to traditional methods that use external stimuli (e.g., heat or light) to trigger film cross-linking. The process requires short cross-linking times (

Burst release of a payload from polymeric particles upon photoirradiation was engineered by altering the cross-linking density. This was achieved via a dual cross-linking concept whereby noncovalent cross-linking was provided by cyclodextrin host-guest interactions, and irreversible covalent cross-linking was mediated by continuous assembly of polymers (CAP). The dual cross-linked particles (DCPs) were efficiently infiltrated (∼80-93%) by the biomacromolecule dextran (molecular weight up to 500 kDa) to provide high loadings (70-75%). Upon short exposure (5 s) to UV light, the noncovalent cross-links were disrupted resulting in increased permeability and burst release of the cargo (50 mol % within 1 s) as visualized by time-lapse fluorescence microscopy. As sunlight contains UV light at low intensities, the particles can potentially be incorporated into systems used in agriculture, environmental control, and food packaging, whereby sunlight could control the release of nutrients and antimicrobial agents. Refereed/Peer-reviewed

Highly functionalized core cross-linked star (CCS) polymers composed entirely of naturally-occurring amino acids were prepared via the sequential ring-opening polymerisation (ROP) of amino acid Ncarboxyanhydride (NCA) derivatives in a facile one-pot, arm-first strategy. The formation of the star polymers was investigated using side-chain protected poly(3-Z-L-lysine) (PZLL) and poly(g-benzyl-Lglutamic acid) (PBGA) macroinitiators with various molecular weights in combination with a cystine NCA cross-linker to afford poly(3-Z-L-lysine)armspoly(L-cystine)core (PZLLarmsPLCcore) and poly(gbenzyl- L-glutamic acid)armspoly(L-cystine)core (PBLGarmsPLCcore) stars, respectively. As the crosslinker to macroinitiator ratio or macroinitiator molecular weights were increased the molecular weights, average number of arms and core size of the resulting stars also increased. Core-isolated NCA moieties remaining after star formation provided a facile approach to core-functionalization with primary amines bearing different functionalities, including aminomethyl pyrene, propargylamine and hexylamine. UV-vis spectroscopic analysis of PZLLarmsPLCcore and PBLGarmsPLCcore stars corefunctionalised with aminomethyl pyrene provided high loadings of 240 and 128 mol/mol stars, respectively. Furthermore, stars with alkyne functionalized cores were capable of undergoing further click reactions with azido derivatives, demonstrating the accessibility of the core-isolated moieties. Deprotection of the PZLLarmsPLCcore and PBLGarmsPLCcore stars yielded water soluble CCS polymers with poly(L-lysine) and poly(L-glutamic acid) arms, respectively, and functionalised cores. In addition, direct hydrazinolysis of the PBLGarmsPLCcore star provided hydrazide functionalities along the arms, which allow for conjugation of drug molecules via pH sensitive hydrazone linkers. These results open up exciting opportunities for the development of star polymer drug delivery systems, whereby a lack of functionality, biocompatibility and biodegradability are often limiting factors. Refereed/Peer-reviewed

Core crosslinked star (CCS) polymers ae synthesized and blended with linear polymers. Constrained mobility is revealed by an increase in modulus and strength with CCS polymer concentration, while creep deformation decreases and permanent strain increases. Storage modulus, loss modulus, and glass transition temperature increase with CCS polymer concentration due to miscibility and linear-CCS polymer "arm" interactions. Master curves shift to lower frequencies with blends that experience segmental relaxation across a broader time scale due to a range of molecular environments from linear to maximum constraints in the vicinity of the crosslinked cores. Fragility and apparent activation energy increase with CCS polymer content, while fractional free volume and volume expansion decrease. Refereed/Peer-reviewed

Blends of linear and core-crosslinked star (CCS) polymers are prepared. The relaxation and thermal properties of the blends are determined using conventional and modulated-temperature DSC and modulated-temperature thermomechanometry. Addition of CCS polymers increase the glass transition temperature while decreasing the enthalpy and the linear coefficient of thermal expansion, suggesting that the hyperbranched polymers restrict matrix chain motions. Isothermal annealing increased the Tg and ΔH and decreased sub-Tg α due to the reduced free volume and mobility within the polymer films. Volume relaxation during annealing is observed using mT-TM, while a stretched-exponential function is utilised to interpret the data. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An efficient and versatile synthetic route toward highly functionalized core cross-linked star (CCS) polymers with interesting structures and properties is presented using an alkyne CCS polymer as scaffold. The alkyne CCS polymer scaffold was initially prepared via an improved arm-first approach, through ring-opening polymerization (ROP) of 4,40- bioxepanyl-7,70-dione (BOD) with a poly(caprolactone-b-propargyl methacrylate) macroinitiator and stannous triflate (Sn(OTf)2) catalyst. Highly functionalized fluorescent, saccharide and amphiphilic CCS polymers were synthesized by grafting the alkyne CCS polymer with the corresponding azido substituted compounds via copper catalyzed 1,3-dipolar azide alkyne cycloaddition (CuAAC), 'click' chemistry. The resulting coronafunctionalized CCS polymers were characterized via GPC, 1H NMR spectroscopic analysis and DLS. 1H NMR spectroscopic analysis revealed that the grafting efficiency (i.e., click efficiency) ranged from 10 to >99%and was highly dependent on the structure and functionality of the azido compounds. This equates to the grafting of 45 to 450 functional compounds onto the CCS polymer scaffolds corona. The results indicate that the click functionalization efficiency is closely related to the molecular size of the azido compounds. Other than size, factors including molecular structure, compatibility and synergistic driving forces, such as the formation of potential inclusion complexes, are also found to affect the functionalization efficiencies. Refereed/Peer-reviewed

A general method for the synthesis of well-defined multistar assemblies (in which the stars contain cross-linked cores) involving the atom transfer radical polymerization (ATRP) of macroinitiators (MIs) and cross-linker with the use of telechelic macroinitiators (TMIs) as the connecting blocks is described. Isolation of each type of multistar assembly with a high degree of specificity was achieved via a simple fractional precipitation process. Selective degradation of the PMMA-based and PtBMA-based multistar assemblies into their individual star units via cleavage of the disulfide group within the connecting blocks confirmed the synthesis of well-defined, low-polydispersity PMMA-based tristar and dumbbell polymers and PtBMA-based tetrastar, tristar, and dumbbell polymers. Hydrolysis of the PtBMA-based assemblies afforded amphiphilic poly(methacrylic acid) (PMAA) multistar assemblies and dumbbell polymers with enhanced pH responsiveness over their single star analogues, with changes in dh of 42% and 30%, respectively (this is in comparison to 22% for discrete PMAA CCS polymers). Furthermore, the first reported native-state images of these PMAA-based multistar assemblies and CCS polymers in solution obtained using cryogenic transmission electron microscopy (cryo-TEM) are presented, revealing the different conformations of the various multistar assemblies. Refereed/Peer-reviewed

A series of novel amphiphilic diblock copolymers composed of hydrophilic linear poly(ethylene glycol) (PEG) and linear brush hydrophobic polydimethylsiloxane (PDMS) were synthesized. Three different molecular weights of monomethyl ether PEG were initially functionalized with 2-bromoisobutyryl bromide to afford macroinitiators suitable for atom-transfer radical polymerization. The macroinitiators were characterized by gel permeation chromatography, 1 H and 13 C nuclear mag- netic resonance spectroscopic analysis and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy. The three different molecular weight macroinitiators were then chain extended with monomethacryloxypropyl-terminated PDMS and photoactive 2-(methylacyloyloxy)ethyl anthracene-9- carboxylate in different molar ratios to afford a series of photo- responsive amphiphilic diblock copolymers with high conver- sions. Self-assembly of these linear-linear brush diblock copolymers in N,N-dimethylformamide afforded nanoparticles with hydrodynamic diameters (dH) ranging from 41 to 268 nm, as determined by dynamic light scattering analysis. Crosslink- ing and stabilization of the nanoparticles was achieved via (414) photodimerization of the anthracene moieties upon exposure to UV radiation at 365 nm with the reverse reaction studied at a wavelength of 254 nm. Transmission electron microscopy revealed that the self-assembled nanoparticles and their crosslinked derivatives had spherical morphologies. V C 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 00, 000-000

The generation of nanoscale polymer films using complex, hierarchically structured (bio)macromolecular architectures has important implications in the field of materials science. This study details the surface-confined covalent cross-linking of micellar macrocross-linkers derived from the amphiphilic diblock copolymer, polystyrene-b- poly(N-(2-hydroxypropyl)methacrylamide), via atom transfer radical polymerization (ATRP)-mediated continuous assembly of polymers (CAPATRP), to generate compartmentalized thin films with unique surface morphologies. Using initiator- functionalized silicon wafers, the micellar films were found to be thicker in comparison to thin films prepared from linear macrocross-linkers derived from poly(N-(2-hydroxypropyl)- methacrylamide) (15.2 vs 10.2 nm). Unlike the smooth and flat surface morphologies observed for films prepared from the linear macrocross-linker, the micellar films possessed distinctive pitted morphologies that became more pronounced after annealing. Furthermore, the hydrophobic polystyrene cores of the micelles enabled the encapsulation of hydrophobic molecules that subsequently remain compartmentalized during the CAP process, as demonstrated with the encapsulation of the dye Nile Red. The assembly of Nile Red-loaded micelles onto initiator-functionalized silica particles was confirmed via fluorescence microscopy. This study demonstrates the efficiency and versatility of the CAP approach to generate nanostructured thin films with controllable morphology, surface roughness, thickness, and composition, simply by varying the macromolecular architecture. Refereed/Peer-reviewed

A series of poly(( 1H,1H -pentafluoropropyl acrylate)- ran -(methyl methacrylate)) (poly(PFPA- ran -MMA)) star polymers with varying fluorine content were prepared via the core-first approach using atom-transfer radical polymerisation (ATRP). Subsequently, the star polymers were used to prepare honeycomb films on both planar and non-planar surfaces via the ‘Breath Figures’ technique using a static casting method. The fluorine content of the star polymers was observed to influence the morphology of the honeycomb structures and the formation of non-cracking honeycomb films on non-planar surfaces. Moreover, the average pore diameter of the honeycomb films was found to decrease with increasing fluorine content, as well as increasing polymer concentration in the casting solution or decreasing humidity during casting. The increasing fluorine content of the star polymers was also found to result in a decrease in their glass transition temperatures and Young's modulus values.

UV irradiation of hitherto unknown 4,5-bis-benzol[b]thiophen-3-yl-[1,3]dithiol-2-one gave 3-(3-benzo[b]thienyl)-thieno[3,4-c]benzo[ e][1,2]dithine by loss of carbon monoxide and rearrangement, whereas 4,5-bis-(2-bromo-phenyl)-[1,3]dithiol-2-one gave a polymeric material containing S-S bridges. The Structures of both photoproducts were demonstrated on the basis of chemical behaviour and/or X-ray diffraction. (C) 2009 Elsevier Ltd. All rights reserved.

Water-soluble poly(2-hydroxyethyl acrylate) (PHEA)-based core cross-linked star polymers were efficiently synthesised with high macroinitiator-to-star-conversion (>95 %) in a one-pot system via single electron transfer-living radical polymerisation. The star polymers display excellent water solubility and the pendant hydroxyl groups provide a platform for facile post-functionalisation with various molecules. In demonstrating this, a photo-isomerisable molecule, 4-(phenylazo)benzoic acid was conjugated onto the preformed stars through partial esterification of the available hydroxyl groups (5-20 %). The azobenzene functionalised stars were subsequently employed to form reversible inclusion complexes with α-cyclodextrin. Refereed/Peer-reviewed

A novel and highly efficient one-pot two-step strategy towards core cross-linked star polymers based on single electron transfer-living radical polymerization (SET-LRP) is described. Macroinitiators with high end-group fidelity were generated at high monomer conversions prior to the addition of cross-linkable monomers in the same pot to induce the formation of star polymers. Quantitative (>99%) star formation is achieved without the purification of unreacted monomers or macroinitiators. Refereed/Peer-reviewed

Star polymers are comprised of multiple arms or branches radiating from a central point or core and have been of huge scientific interest since they were first prepared sixty years ago, as a result of their unique physical properties. Star polymers are not just an academic curiosity, but are currently employed or under investigation in a wide range of industries and commercial materials ranging from engine oils and coating technologies to contact lenses and biomedical devices. Although there are many different types of star polymers and methods for their synthesis, recent advances in the field of controlled radical polymerisation have enabled the facile production of complex star polymer architectures from a large range of monomer families, without the requirement of highly stringent reaction conditions. In particular, well-defined, nanometre scale core cross-linked star (CCS) polymers, which are readily accessible by controlled radical polymerisation techniques, have been increasingly prominent in the scientific literature. As a result, this feature article provides a comprehensive review covering the development, functionalisation, physical properties and application of core cross-linked star polymers prepared by controlled radical polymerisation and the arm-first approach. Refereed/Peer-reviewed