New amphiphilic block copolymers S nSz m consisting of blocks with varied degrees of polymerization, n and m, of polystyrene, S, and polystyrene carrying an amphiphilic polyoxyethylene-polytetrafluoroethylene chain side-group, Sz, were prepared by controlled atom transfer radical polymerization (ATRP). The block copolymers, either alone or in a blend with commercial SEBS (10 wt% SEBS), were spin-coated in thinner films (200-400 nm) on glass and spray-coated in thicker films ( approximately 500 nm) on a SEBS underlayer (150-200 microm). Angle-resolved X-ray photoelectron spectroscopy (XPS) measurements proved that at any photoemission angle, varphi, the atomic ratio F/C was larger than that expected from the known stoichiometry. Consistent with the enrichment of the outer film surface (3-10 nm) in F content, the measured contact angles, theta, with water (theta w > or = 107 degrees ) and n-hexadecane (theta h > or = 64 degrees ) pointed to the simultaneous hydrophobic and lipophobic character of the films. The film surface tension gamma S calculated from the theta values was in the range 13-15 mN/m. However, the XPS measurements on the "wet" films after immersion in water demonstrated that the film surface underwent reconstruction owing to its amphiphilic nature, thereby giving rise to a more chemically heterogeneous structure. The atomic force microscopy (AFM) images (tapping mode/AC mode) revealed well-defined morphological features of the nanostructured films. Depending on the chemical composition of the block copolymers, spherical (ca. 20 nm diameter) and lying cylindrical (24-29 nm periodicity) nanodomains of the S discrete phase were segregated from the Sz continuous matrix (root-mean-square, rms, roughness approximately 1 nm). After immersion in water, the underwater AFM patterns evidenced a transformation to a mixed surface structure, in which the nanoscale heterogeneity and topography (rms = 1-6 nm) were increased. The coatings were subjected to laboratory bioassays to explore their intrinsic ability to resist the settlement and reduce the adhesion strength of two marine algae, viz., the macroalga (seaweed) Ulva linza and the unicellular diatom Navicula perminuta. The amphiphilic nature of the copolymer coatings resulted in distinctly different performances against these two organisms. Ulva adhered less strongly to the coatings richer in the amphiphilic polystyrene component, percentage removal being maximal at intermediate weight contents. In contrast, Navicula cells adhered less strongly to coatings with a lower weight percentage of the amphiphilic side chains. The results are discussed in terms of the changes in surface structure caused by immersion and the effects such changes may have on the adhesion of the test organisms.
In the present work, we confirm the observation from Ianniruberto and Marrucci [1] that entangled melts of branched polystyrenes behave like linear polystyrenes in the steady state of fast extensional flow, by measuring a linear, an asymmetric star and a symmetric star polystyrenes with the same span molecular weight (180 kg/mol). We show that all three melts reach the same extensional steady-state viscosity in fast extensional flow (faster than the inverse Rouse time). We further measure stress relaxation following steady extensional flow for the three melts. We show that initially they relax in a similar way, most likely via arm retraction, at short time, but behave differently at long time due to both the length of the arm and the branch point. The terminal relaxation is described by a Doi and Edwards based model, i.e. considering pure orientational relaxation.
(2015) 'Chain architecture as an orthogonal parameter to inuence block copolymer morphology. The synthesis and characterisation of hyperbranched block copolymers : HyperBlocks. ', Macromolecules., 48 (24). pp. 8806-8822. Further information on publisher's website:http://dx.doi.org/10.1021/acs.macromol.5b02052 Publisher's copyright statement: This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Macromolecules, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/acs.macromol.5b02052. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. HyperBlocks with a commercially available linear ABA triblock copolymeric thermoplastic elastomer were prepared. Moreover, the "macromonomer" approach is the only feasible route to prepare hyperbranched block copolymers. The solid-state morphology of the resulting materials was investigated by a combination of transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) which showed a dramatic impact of the chain architecture on the resulting morphology. Whilst the linear ABA triblock copolymers showed the expected microphase-separated morphology with long-range order dependent upon composition, no long-range order was observed in the HyperBlocks. Instead the HyperBlocks revealed a microphase-separated morphology without long-range lattice order, irrespective of macromonomer composition or molecular weight. Furthermore, when HyperBlocks were subsequently blended with a commercially available linear ABA triblock copolymer (Kraton D1160 TM ) the HyperBlock appeared to impose a microphase separated morphology without long-range lattice order upon the linear copolymer even when the HyperBlock is present as the minor component in the blend at levels as low as 10% by weight.
. (2013) 'Synthesis and temperature gradient interaction chromatography of model asymmetric star polymers by the "macromonomer"approach.', European polymer journal., 49 (9). pp. 2769-2784. Further information on publisher's website:http://dx.doi.org/10.1016/j.eurpolymj.2013.06.021Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in European Polymer Journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be re ected in this document. Changes may have been made to this work since it was submitted for publication. A de nitive version was subsequently published in European Polymer Journal, 49, 9, 2013Journal, 49, 9, , 10.1016Journal, 49, 9, /j.eurpolymj.2013.021. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract. We describe herein the synthesis and characterisation of a series of asymmetric three arm polystyrene stars via the "macromonomer" approach. The stars have been designed as model polymers to probe branched polymer dynamics and in particular to establish the chain-length of side-arm which precipitates a change in the rheological properties of the resulting polymers from "linear-like" to "star-like". Thus, a homologous series of three arm stars have been prepared in which the molar mass of two (long) arms are fixed at 90 000 gmol -1 and the molar mass of the remaining (short) arm is varied from below the entanglement molecular weight (M e ) to above M e . The arms were prepared by living anionic polymerisation, resulting in well-defined chain lengths with narrow molecular weight distribution. In contrast to the usual chlorosilane coupling approach, the macromonomer approach involves the introduction of reactive chain-end functionalities on each of the arms, either through the use of a functionalised (protected) initiator or a functional end-capping agent, which allows the stars to be constructed by a simple condensation coupling reaction. In this study we will compare the relative efficiency of a Williamson and 'click' coupling reaction in producing the stars. Most significantly, although this approach maybe a little more time-consuming than the more common silane coupling reaction, in the present study the "long" arm may be produced in sufficient quantity such that all of the asymmetric stars are produced with long arms of identical molecular weight -the only remaining variable being the molecular weight of th...
(2015) 'Normal-phase (temperature gradient) interaction chromatography A powerful tool for the characterisation of high molecular weight chain-end functionalised polymers.', European polymer journal., 73 . pp. 105-115. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. is all the more remarkable that complete (baseline) resolution can be achieved for two polymers with an identical molar mass (< 200,000 gmol -1 ), which differ only in that one sample is functionalised with a single primary alcohol group.
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