Copper(0)-mediated radical polymerisation in a self-generating biphasic system

Herein, we demonstrate the synthesis of well-defined poly(n-alkyl acrylate)s via copper(0)-mediated radical polymerisation in a self-generating biphasic system. During the polymerisation of n-butyl acrylate in DMSO, the polymer phase separates to yield a polymer-rich layer with very low copper content (ICP-MS analysis: 0.016 wt%). The poly(n-butyl acrylate) has been characterized by a range of techniques, including GPC, NMR and MALDI-TOF, to confirm both the controlled character of the polymerisation and the end group fidelity. Moreover, we have successfully chain extended poly(n-butyl acrylate) in this biphasic system several times with n-butyl acrylate to high conversion without intermediate purification steps. A range of other alkyl acrylates have been investigated and the control over the polymerisation is lost as the hydrophobicity of the polymer increases due to the increase in alkyl chain length indicating that it is important for the monomer to be soluble in the polar solvent

Rapidly self-deoxygenating controlled radical polymerization in water via in situ disproportionation of Cu(i)

Rapidly self-deoxygenating Cu-RDRP in aqueous media is investigated. The disproportionation of Cu(I)/Me6Tren in water towards Cu(II) and highly reactive Cu(0) leads to O2-free reaction environments within the first seconds of the reaction, even when the reaction takes place in the open-air. By leveraging this significantly fast O2-reducing activity of the disproportionation reaction, a range of well-defined water-soluble polymers with narrow dispersity are attained in a few minutes or less. This methodology provides the ability to prepare block copolymers via sequential monomer addition with little evidence for chain termination over the lifetime of the polymerization and allows for the synthesis of star-shaped polymers with the use of multi-functional initiators. The mechanism of self-deoxygenation is elucidated with the use of various characterization tools, and the species that participate in the rapid oxygen consumption is identified and discussed in detail

Steady state performance of discrete linear time-invarient systems

Transients mask the initial portion of an output signal preventing immediate analysis of the desired operational steady-state response and requiring, at times, lengthy simulation techniques to be employed. This investigation demonstrates a method for readily determining initial conditions that suppress transient solutions to forced discrete-time linear systems, and addresses the necessary theoretical precursors to obtaining the steady-state components of a response. The method is applicable to stable as well as, in principle, unstable systems of any order

Dual-functional materials via CCTP and selective orthogonal thiol-Michael addition/epoxide ring opening reactions

Poly(glycidyl methacrylate) (PGMA) has been synthesised by cobalt catalysed chain transfer polymerisation (CCTP) yielding, in one step, polymers with two points for post polymerisation functionalisation; the activated terminal vinyl bond and in chain epoxide groups. Epoxide ring-opening and a combination of thiol-Michael addition and epoxide ring-opening has been used for the post-functionalisation with amines and thiols to prepare a range of functional materials

From suburb to compact city

Planning of cities today is often focused on delivering a compact built structure and more green structure, since both these are regarded as sustainable solutions. However, the increasingly compact city form decreases the green spaces while the ecological functions of greenery is a fundamental part of a well-functioning compact city. For this reason, this thesis seeks to investigate how the compact city ideal redefines the role and reshapes the geography of the green structure. A planning historical research enables an understanding of different roles of green structure over time, to provide answers to how the green structure has been redefined. A closer study of contemporary planning that incorporates the compact city ideal and also urban ecology to enhance the green structure, acknowledges how the green structure is being reshaped. These are carried out in a qualitative case study of Swedish municipal planning, through the single case of Upplands Väsby municipality. The current vision of Upplands Väsby municipality is to go from being a suburb to becoming a green city and the already compact part of the municipality is undergoing further densification. This makes Upplands Väsby an interesting case where the compact city ideal’s influence on the green structure can be investigated. The planning historical research shows shifts over time in vision, purpose, strategy and balancing of interests, regarding the green structure in municipal plans. It also shows how the construction of the compact city ideal has redefined the role of the green structure over time, to successively contain more functions with increasing focus on ecology. The study of contemporary planning reveals how the compact city ideal reshapes the geography of the green structure, by mainly giving space to well-organized green structure with clear purposes and multiple functions. Green spaces are thus shrinked. If these functions are shown to impair one another’s purposes, this would create a problem caused by the contemporary planning ideal of the compact city, for further planning to solve. Such construction of previous problems and how planning has attempted to solve these, is highlighted by the historical approach in this study. Hence, this study may encourage contemporary planning to question the strong compact city ideal as the default solution

A detailed study on understanding glycopolymer library and Con A interactions

Synthetic glycopolymers are important natural oligosaccharides mimics for many biological applications. To develop glycopolymeric drugs and therapeutic agents, factors that control the receptor-ligand interaction need to be investigated. A library of well-defined glycopolymers has been prepared by the combination of copper mediated living radical polymerization and CuAAC click reaction via post-functionalization of alkyne-containing precursor polymers with different sugar azides. Employing Concanavalin A as the model receptor, we explored the influence of the nature and densities of different sugars residues (mannose, galactose, and glucose) on the stoichiometry of the cluster, the rate of the cluster formation, the inhibitory potency of the glycopolymers, and the stability of the turbidity through quantitative precipitation assays, turbidimetry assays, inhibitory potency assays, and reversal aggregation assays. The diversities of binding properties contributed by different clustering parameters will make it possible to define the structures of the multivalent ligands and densities of binding epitopes tailor-made for specific functions in the lectin-ligand interaction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2588–259

David Sherrington commemorative issue

This themed issue of Polymer Chemistry was commissioned following the passing, in October 2014, of Professor David Colin Sherrington, FRS. It was commissioned as a dedication to the memory of a world-class polymer chemist of international renown, as well as a celebration of a subject area that was very close to Dave's heart and upon which he founded his career and made his name. It is entirely appropriate that this collection of papers is published in a leading international journal that bears the name of the subject field with which Dave's name is synonymous and to which he contributed so much – Polymer Chemistry – and that this collection be published in the UK by his own professional chemical society, the Royal Society of Chemistry

α-aldehyde terminally functional methacrylic polymers from living radical polymerization : application in protein conjugation “pegylation”

Application of proteins and peptides as human therapeutics is expanding rapidly as drug discovery becomes more prevalent. Conjugation of polymers to proteins can circumvent many problems and pegylation of proteins is now emerging as acceptable practice. This paper describes the synthesis of α-aldehyde-terminated poly(methoxyPEG)methacrylates from Cu(I) mediated living radical polymerization (Mn = 11 000, 22 000 and 32 000; PDi < 1.15), and their efficient conjugation to lysozyme, as a model protein. This offers an attractive and flexible alternative to linear poly(ethylene glycol) opening up the possibility of using the full power of living radical polymerization

Defect-related luminescent nanostructured hydroxyapatite promotes mineralization through both intracellular and extracellular pathways

Hydroxyapatite (HAP) is a widely used biomaterial for bone tissue substitution due to its chemical similarity with the natural bone. Defect-related luminescent HAP materials have the same chemical composition as normal HAP and excellent biocompatibility. However, only few works have focused on the defect-related luminescent HAP materials on bone regeneration. In this work, we systematically investigated the bone regeneration pathway induced by nanostructured particles using defect-related luminescent hydroxyapatite (S2) materials. We monitored the subcellular distribution and location of S2 during osteoblast differentiation with the property of defect-related luminescence. Nano-scale S2 could be internalized by osteoblasts (OBs) via caveolae-mediated endocytosis and macropinocytosis. S2 incorporated into the lysosomes dissolved and released calcium ions for the formation of mineralized nodules. Extracellular S2 also promoted bone regeneration as a nucleation site. Taken together, the physical properties of hydroxyapatite control the bone regeneration pathway in osteoblasts

Feasibility of the Simultaneous Determination of Monomer Concentrations and Particle Size in Emulsion Polymerization Using in Situ Raman Spectroscopy.

An immersion Raman probe was used in emulsion copolymerization reactions to measure monomer concentrations and particle sizes. Quantitative determination of monomer concentrations is feasible in two-monomer copolymerizations, but only the overall conversion could be measured by Raman spectroscopy in a four-monomer copolymerization. The feasibility of measuring monomer conversion and particle size was established using partial least-squares (PLS) calibration models. A simplified theoretical framework for the measurement of particle sizes based on photon scattering is presented, based on the elastic-sphere-vibration and surface-tension models.The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (EC FP7) Grant Agreement n. [NMP2-SL-2012-280827] and Engineering and Physical Sciences Research Council under grant EP/L003309/1.This is the final version of the article. It first appeared from the American Chemical Society via http://dx.doi.org/10.1021/acs.iecr.5b0275