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ACS Macro Letters

Jingling Zhang, Guofang Li, Nicole S Sampson
We previously reported that cyclohexene and bicyclo[4.2.0]oct-1(8)-ene-8-carboxamides undergo efficient ruthenium-catalyzed alternating ring-opening metathesis polymerization (AROMP). Here, we demonstrate that cyclodecene and cyclododecene also function as cycloalkene monomers in the bicyclo[4.2.0]oct-1(8)-ene-8-carboxamide AROMP system, thus enabling the synthesis of linear alternating copolymers with spacers of different lengths, as demonstrated by means of NMR spectroscopy and gel permeation chromatography...
September 18, 2018: ACS Macro Letters
Pezhman Mohammadi, Grégory Beaune, Bjørn Torger Stokke, Jaakko V I Timonen, Markus B Linder
Liquid-liquid phase separation of biomacromolecules plays a critical role in many of their functions, both as cellular components and in structural assembly. Phase separation is also a key mechanism in the assembly of engineered recombinant proteins for the general aim to build new materials with unique structures and properties. Here the phase separation process of an engineered protein with a block-architecture was studied. As a central block, we used a modified spider silk sequence, predicted to be unstructured...
September 18, 2018: ACS Macro Letters
Niels L Meereboer, Ivan Terzić, Sarah Saidi, Daniel Hermida Merino, Katja Loos
The electroactive properties of poly(vinylidene fluoride) (PVDF) are a direct consequence of its crystalline phases. Although poorly understood, nanostructuring PVDF in confined geometries can drastically change its crystallization behavior. Therefore, we synthesized a variety of PVDF-based triblock copolymers to gain a better understanding of the melt crystallization and explore how crystallization is affected by the morphology and chemical nature of the amorphous block. Differential scanning calorimetry, small-/wide-angle X-ray scattering, and transmission electron microscopy gave us excellent insights into the morphology and the corresponding crystalline phases...
July 17, 2018: ACS Macro Letters
Anindita Das, Katja Petkau-Milroy, Gilian Klerks, Bas van Genabeek, René P M Lafleur, Anja R A Palmans, E W Meijer
Intriguingly, little is known about the impact of dispersity on the crystallization driven self-assembly (CDSA) of amphiphilic block copolymers in aqueous media. Here, we investigate the influence of dispersity on the CDSA of ABA-type amphiphilic block co-oligomers (ABCOs). Two pairs of ABCOs are synthesized comprising discrete ( Đ = 1.00) or disperse ( Đ = 1.20) isotactic l-lactic acid 16-mers as the semicrystalline hydrophobic block and either oligo(ethylene glycol) methyl ether (MeOoEG) or oligo(tetraethylene glycol succinate) (oTEGSuc) as the discrete hydrophilic block...
May 15, 2018: ACS Macro Letters
Hung V-T Nguyen, Nolan M Gallagher, Farrukh Vohidov, Yivan Jiang, Ken Kawamoto, Hui Zhang, Jiwon V Park, Zhihao Huang, M Francesca Ottaviani, Andrzej Rajca, Jeremiah A Johnson
The polymerization of functional monomers provides direct access to functional polymers without need for postpolymerization modification; however, monomer synthesis can become a bottleneck of this approach. New methods that enable rapid installation of functionality into monomers for living polymerization are valuable. Here, we report the three-step convergent synthesis (two-step longest linear sequence) of a divalent exo -norbornene imide capable of efficient coupling with various nucleophiles and azides to produce diversely functionalized branched macromonomers optimized for ring-opening metathesis polymerization (ROMP)...
April 17, 2018: ACS Macro Letters
Antti Korpi, Chao Ma, Kai Liu, Nonappa, Andreas Herrmann, Olli Ikkala, Mauri A Kostiainen
Self-assembly is a convenient process to arrange complex biomolecules into large hierarchically ordered structures. Electrostatic attraction between the building blocks is a particularly interesting driving force for the assembly process, as it is easily tunable and reversible. Large biomolecules with high surface charge density, such as proteins and protein cages, are very promising building blocks due to their uniform size and shape. Assemblies of functional molecules with well-defined nanostructures have wide-ranging applications but are difficult to produce precisely by synthetic methods...
March 20, 2018: ACS Macro Letters
Mikko Poutanen, Zafar Ahmed, Lauri Rautkari, Olli Ikkala, Arri Priimagi
Photoisomerization of azobenzene derivatives is a versatile tool for devising light-responsive materials for a broad range of applications in photonics, robotics, microfabrication, and biomaterials science. Some applications rely on fast isomerization kinetics, while for others, bistable azobenzenes are preferred. However, solid-state materials where the isomerization kinetics depends on the environmental conditions have been largely overlooked. Herein, an approach to utilize the environmental sensitivity of isomerization kinetics is developed...
March 20, 2018: ACS Macro Letters
Sangho Won, Steven Hindmarsh, Matthew I Gibson
Carbohydrate-carbohydrate interactions are proposed to be biologically significant but have lower affinities than the well-studied carbohydrate-protein interactions. Here we introduce multivalent glyconanostructures where the surface expression of lactose can be triggered by an external stimulus, and a gold nanoparticle core enables colorimetric signal outputs to probe binding. Macromolecular engineering of a responsive polymer "gate" enables the lactose moieties to be presented only when an external stimulus is present, mimicking how nature uses enzymes to dynamically regulate glycan expression...
February 20, 2018: ACS Macro Letters
Liye Fu, Antonina Simakova, Marco Fantin, Yi Wang, Krzysztof Matyjaszewski
An iron porphyrin catalyst, derived from the active center of proteins such as horseradish peroxidase and hemoglobin, was successfully used for the atom transfer radical polymerizations (ATRP) of methacrylic acid. ATRP of methacrylic acid and other acidic monomers is challenging due to Cu complexation by carboxylates, protonation of the ligand, and displacement of the halogen chain end. A robust mesohemin-based catalyst provided controlled ATRP of methacrylic acid, yielding poly(methacrylic acid) with M n ≥ 20000 and dispersity Đ < 1...
January 16, 2018: ACS Macro Letters
Hsiao-Ping Hsu, Kurt Kremer
Polymer material properties are strongly affected by entanglement effects. For long polymer chains and composite materials, they are expected to be at the origin of many technically important phenomena, such as shear thinning or the Mullins effect, which microscopically can be related to topological constraints between chains. Starting from fully equilibrated highly entangled polymer melts, we investigate the effect of isochoric elongation on the entanglement structure and force distribution of such systems...
January 16, 2018: ACS Macro Letters
Guillaume Hedir, Christopher Stubbs, Phillip Aston, Andrew P Dove, Matthew I Gibson
Poly(vinyl alcohol) (PVA) is the most active synthetic mimic of antifreeze proteins and has extremely high ice recrystallization inhibition (IRI) activity. Addition of PVA to cellular cryopreservation solutions increases the number of recovered viable cells due to its potent IRI, but it is intrinsically nondegradable in vivo . Here we report the synthesis, characterization, and IRI activity of PVA containing degradable ester linkages. Vinyl chloroacetate (VClAc) was copolymerized with 2-methylene-1,3-dioxepane (MDO) which undergoes radical ring-opening polymerization to install main-chain ester units...
December 19, 2017: ACS Macro Letters
Imke A B Pijpers, Loai K E A Abdelmohsen, David S Williams, Jan C M van Hest
Biodegradable nanoarchitectures, with well-defined morphological features, are of great importance for nanomedical research; however, understanding (and thereby engineering) their formation is a substantial challenge. Herein, we uncover the supramolecular potential of PEG-PDLLA copolymers by exploring the physicochemical determinants that result in the transformation of spherical polymersomes into stomatocytes. To this end, we have engineered blended polymersomes (comprising copolymers with varying lengths of PEG), which undergo solvent-dependent reorganization inducing negative spontaneous membrane curvature...
November 21, 2017: ACS Macro Letters
Lewis D Blackman, Spyridon Varlas, Maria C Arno, Alice Fayter, Matthew I Gibson, Rachel K O'Reilly
Enzyme loading of polymersomes requires permeability to enable them to interact with the external environment, typically requiring addition of complex functionality to enable porosity. Herein, we describe a synthetic route towards intrinsically permeable polymersomes loaded with functional proteins using initiator-free visible light-mediated polymerization-induced self-assembly (photo-PISA) under mild, aqueous conditions using a commercial monomer. Compartmentalization and retention of protein functionality was demonstrated using green fluorescent protein as a macro-molecular chromophore...
October 31, 2017: ACS Macro Letters
Brandon L Peters, Darin Q Pike, Michael Rubinstein, Gary S Grest
Polymers confined to the liquid/vapor interface are studied using molecular dynamics simulations. We show that for polymers which are weakly immiscible with the solvent, the density profile perpendicular to the liquid/vapor interface is strongly asymmetric. On the vapor side of the interface, the density distribution falls off as a Gaussian with a decay length on the order of the bead diameter, whereas on the liquid side, the density profile decays as a simple exponential. This result differs from that of a polymer absorbed from a good solvent with the density profile decaying as a power law...
October 11, 2017: ACS Macro Letters
Debra J Audus, Juan J de Pablo
We are entering an era where large volumes of scientific data, coupled with algorithmic and computational advances, can reduce both the time and cost of developing new materials. This emerging field known as materials informatics has gained acceptance for a number of classes of materials, including metals and oxides. In the particular case of polymer science, however, there are important challenges that must be addressed before one can start to deploy advanced machine learning approaches for designing new materials...
October 2017: ACS Macro Letters
Magdalena Szymusiak, Joseph Kalkowski, Hanying Luo, Alexander J Donovan, Pin Zhang, Chang Liu, Weifeng Shang, Thomas Irving, Margarita Herrera-Alonso, Ying Liu
A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core-shell micelles composed of linear diblock copolymers poly(ethylene glycol)- b -poly(caprolactone) (PEG- b -PCL), poly(ethylene oxide)- b -poly(lactic acid) (PEG- b -PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA- g -PEG/PLA) were characterized by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core-shell size, and aggregation number...
September 19, 2017: ACS Macro Letters
Jingwei Fan, Yannick P Borguet, Lu Su, Tan P Nguyen, Hai Wang, Xun He, Jiong Zou, Karen L Wooley
Well-defined molecular brushes bearing polypeptides as side chains were prepared by a "grafting through" synthetic strategy with two-dimensional control over the brush molecular architectures. By integrating N-carboxyanhydride ring-opening polymerizations (NCA ROPs) and ring-opening metathesis polymerizations (ROMPs), desirable segment lengths of polypeptide side chains and polynorbornene brush backbones were independently constructed in controlled manners. The N2 flow accelerated NCA ROP was utilized to prepare polypeptide macromonomers with different lengths initiated from a norbornene-based primary amine, and those macromonomers were then polymerized via ROMP...
September 19, 2017: ACS Macro Letters
Nicholas S Vail, Christopher Stubbs, Caroline I Biggs, Matthew I Gibson
Polymer mimics of antifreeze proteins are emerging as an exciting class of macromolecular cryoprotectants for the storage of donor cells and tissue. Poly(vinyl alcohol), PVA, is the most potent polymeric ice growth inhibitor known, but its mode of action and the impact of valency (DP) are not fully understood. Herein, tandem RAFT polymerization and column chromatography are used to isolate oligomers with dispersities <1.01 to enable the effect of molecular weight distribution, as well as length, to be probed...
August 30, 2017: ACS Macro Letters
Bas van Genabeek, Bas F M de Waal, Bianca Ligt, Anja R A Palmans, E W Meijer
An experimental study is presented in which we compare the bulk phase behavior of discrete and (partially) disperse diblock co-oligomers (BCOs) with high χ-low N. To this end, oligomers of dimethylsiloxane (oDMS) and lactic acid (oLA) were synthesized, each having either a discrete number of repeat units or a variable block length. Ligation of the blocks resulted in oDMS-oLA BCOs with dispersities ranging from <1.00001 to 1.09, as revealed by mass spectroscopy and size exclusion chromatography. The phase behavior of all BCOs was investigated by differential scanning calorimetry and small-angle X-ray scattering...
July 18, 2017: ACS Macro Letters
Blaze Heckert, Tuhina Banerjee, Shoukath Sulthana, Shuguftha Naz, Riyadh Alnasser, Deaven Thompson, Guillaume Normand, Jan Grimm, J Manuel Perez, Santimukul Santra
In this study, we have synthesized a new hyperbranched polyester polymer containing sulfur-pendants (HBPE-S) in the branching points. This HBPE-S polymer is composed of spherical shaped, aliphatic three-dimensional architecture with carboxylic acid groups on the surface. The presence of sulfur pendants in the polymeric cavities demonstrated important role in the effective encapsulation of Bi-DOTA complexes ([Bi] = 5.21 μM), when compared to the previously reported polymer without sulfur pendants (HBPE, [Bi] = 1...
March 21, 2017: ACS Macro Letters
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