Synthesis and Characterization of a Thermoresponsive Copolymer with an LCST–UCST-like Behavior and Exhibiting Crystallization

In this work, the diblock copolymer methoxy-poly(ethylene glycol)-block-poly(ε-caprolactone) (MPEG–b-PCL) was synthesized with a block composition that allows this polymer in aqueous media to possess both an upper critical solution temperature (UCST) and a lower critical solution temperature (LCST) over a limited temperature interval. The value of the UCST, associated with crystallization of the PCL-block, depended on heating (H) or cooling (C) of the sample and was found to be CPUCSTH = 32 °C and CPUCSTC = 23 °C, respectively. The LCST was not affected by the heating or cooling scans; assumed a value of 52 °C (CPLCSTH = CPLCSTC). At intermediate temperatures (e.g., 45 °C), dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and cryogenic transmission electron microscopy (cryo-TEM) showed that the solution consisted of a large population of spherical core–shell particles and some self-assembled rodlike objects. At low temperatures (below 32 °C), differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) in combination with SAXS disclosed the formation of crystals with a cylindrical core–shell structure. Cryo-TEM supported a thread-like appearance of the self-assembled polymer chains. At temperatures above 52 °C, incipient phase separation took place and large aggregation complexes of amorphous morphology were formed. This work provides insight into the intricate interplay between UCST and LCST and the type of structures formed at these conditions in aqueous solutions of MPEG–b-PCL diblock copolymers.publishedVersio

Interactions in Aqueous Mixtures of Cationic Hydroxyethyl Cellulose and Different Anionic Bile Salts

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One-pot RAFT and fast polymersomes assembly: a ‘beeline’ from monomers to drug-loaded nanovectors

Rapid and simple routes to functional polymersomes are increasingly needed to expand their clinical or industrial applications. Here we describe a novel strategy where polymersomes are prepared through an in-line process in just a few hours, starting from simple acrylate or acrylamide monomers. Using Perrier's protocol, well-defined amphiphilic diblock copolymers formed from PEG acrylate (mPEGA480), 2-(acryloyloxy)ethyl-3-chloro-4-hydroxybenzoate (ACH) or 2-(3-chloro-4-hydroxybenzamido)ethyl acrylate (CHB), have been synthesised by RAFT polymerisation in one-pot, pushing the monomer conversion for each block close to completion (≥94%). The reaction mixture, consisting of green biocompatible solvents (ethanol/water) have then been directly utilised to generate well-defined polymersomes, by simple cannulation into water or in a more automated process, by using a bespoke microfluidic device. Terbinafine and cyanocobalamine were used to demonstrate the suitability of the process to incorporate model hydrophobic and hydrophilic drugs, respectively. Vesicles size and morphology were characterised by DLS, TEM, and AFM. In this work we show that materials and experimental conditions can be chosen to allow facile and rapid generation drug-loaded polymersomes, through a suitable in-line process, directly from acrylate or acrylamide monomer building blocks

Aid System for Finding Trapped Earthquake Victims

Using Emsuch [6] as a base this reports tries to find a solution to the problems that arise when trying to find survivors in collapsed buildings following an earthquake. Emsuch is a system that allows an user to retrieve information from the Home unit inside a house after an earthquake. But the results of the previous study [6] showed that the previous Emsuch is not very useful in disasters such as earthquakes. This is due to several reasons that were overlooked in that study such as electricity consumption and connectivity. So this study aims to improve the system by designing software that enables the user to quickly check each household that uses an Emsuch system. By using a case study and interviewing members of the Japanese Ground Self-Defence Forces a requirements document was created. From these requirements the system was designed to fulfil them all and then partly implemented and tested. The current prototype of the system has some major parts working, with a few parts non-functional or unimplemented.Den här rapporten använder Emsuch-systemet [6] för att försöka lösa de problem som uppstår när armén letar efter överlevare i husmassor efter jordbävningar i Japan. Med Emsuch kan räddningsarbetarna hämta information från husen de går förbi under letandet. Under en tidigare studie [6] där grunden till systemet utvecklades identifierades flera punkter som leder till problem i de förhållanden som råder i de räddningsaktionerna. De två största utmaningarna är bristen på el och att infrastrukturen för kommunikation ofta är nere. Den här rapporten avser att utforma och implementera en lösning som gör att användarna i armén kan ansluta sig till varje enhet i förbifarten. Med en fallstudie som inkluderar en intervju med Japans markbaserade försvarsstyrkor i Sapporo togs ett kravdokument fram. Detta kravdokument användes som grund för implementeringen av systemet. En prototyp togs fram och testades delvis. Resultatet av testerna visade att Emsuch har potential för att användas i räddningsarbeten, men att det är flera delar som behövs fixas för att klara av verkliga situationer

Grund för effektiv administration av examensarbeten

Som det ser ut idag är hanteringen av examensarbeten, både kandidat och master långt från optimal på Kungliga Tekniska Högskolan (KTH). Administration av detta är onödigt tidskrävande, eftersom det finns ingen överblickbarhet och det är svårt att koppla ihop student med en passande examinator. Bara processen att anmäla studenterna till kursen är en process i flera steg som måste gå igenom många personer. Lösningen som ska ges är ett system som underlättar några steg tillhörande examensarbeten. För att hitta vad för funktioner ett sådant system måste kunna erbjuda utförs studie med hjälp av intervjuer med de som idag administrerar examensarbeten. Resultatet från intervjuerna sammanställdes till en kravspecifikation som sedan användes som bas för att bygga ett system. Systemet består av två grundkomponenter, en databas och en webbapplikation. Webbapplikationen tillåter användaren att komma åt listor sparade i databasen. För att utvärdera systemet sker återkoppling till dessa nyckelpersoner för att erhålla feedback. Uppsatsens resultat består av presentationen utav kravspecifikation, databasdesign och en prototyp av webbapplikationen som är framtagen under arbetet. Huvudmålet är att skapa en prototyp som kan användas av studenter, handledare och examinatorer. De områden som problemet berör är administration, distribuerade system och sammankoppling av resurser

Complex Formation between a Fluorescently-Labeled Polyelectrolyte and a Triblock Copolymer

The association between a randomly pyrene labeled PAA polymer (PAAMePy55) and a PEO−PPO−PEO triblock copolymer (P123) in aqueous solutions of different NaCl concentrations and pHs has been studied by means of dynamic light scattering (DLS) and steady-state fluorescence spectroscopy at 40 °C. At acidic pH values, in the low P123/PAAMePy55 molar ratio regime (i.e., at low P123 concentrations), the relaxation time distributions retrieved from the DLS data analysis were monomodal and very similar to those obtained for the pure PAAMePy55 solution. The apparent hydrodynamic radius of PAAMePy55 at low pH is 18 nm. At higher molar ratios (i.e., at high P123 concentrations), still in the acidic pH regime, bimodal relaxation time distributions were obtained, where the fast relaxation mode is connected to the translational diffusion of free P123 micelles with a hydrodynamic radius obtained at infinite P123 dilution (RH,P123=0) of 10−11 nm. This value coincides perfectly with the hydrodynamic radius of the pure P123 micelles at 40 °C, which was found to be ca. 10 nm at all pH values. The second mode corresponds to a complex consisting of one PAAMePy55 polymer chain and about 42 P123 micelles and with a RH,P123=0 between 35 and 36 nm depending on pH. At pH 9, the mixed system also presented bimodal relaxation time distributions. At this high pH, the intermolecular association between PAAMePy55 and P123 is less strong than at acidic pH according to the steady-state fluorescence measurements. The fast mode is also in this case attributed to free P123 micelles whereas the second mode is related to the so-called “slow mode” commonly observed for polyelectrolyte solutions. In this system, it is related to the formation of multichain domains, that is, large domains formed by several PAAMePy55 chains that move in a common electrostatic field (i.e., a structure factor effect). The presence of P123 micelles does not lead to the total disruption of these domains. They may either contain entrapped P123 micelles or hydrophilic diblock impurities (originating from the P123 sample) that associate with the PAAMePy55 chains

Self-Assembly of a Hydrophobically Modified Naphthalene-Labeled Poly(acrylic acid) Polyelectrolyte in Water:Organic Solvent Mixtures Followed by Steady-State and Time-Resolved Fluorescence

The solution properties of two water-soluble polymers, poly(acrylic acid) (PAA), covalently labeled with the fluorescent hydrophobic dye naphthalene (Np), have been investigated in water:organic solvent mixtures. The naphthalene chromophores have been randomly attached, onto the polymer, with two different degrees of labeling. Fluorescence measurements (steady-state and time-resolved) have been used to follow the photophysical behavior of the polymers and consequently report on the self-association of the polymers in the mixed organic (methanol or dioxane):aqueous solutions. The emission spectra of the high-labeled Np PAA reveal the presence of monomer and excimer bands whereas with the low-labeled polymer only monomer emission is observed. The excitation spectra collected at the monomer and excimer emission bands show significant differences, depending on the water content of the mixture, which indicate the simultaneous presence of preformed and dynamic dimers as routes to excimer formation. The time-resolved data decay profiles of the high-labeled polymer in the mixtures were always triple exponential whereas in pure methanol and dioxane they follow biexponential laws. The data in the mixtures are consistent with two types of monomers and one excimer. Both monomers are able to give rise to excimer in the excited state, one type involving the movement of long distant Np chromophores and the other involving a local reorientation of adjacent Np chromophores. These correspond to different decay times: (1) a long which corresponds to the long distant approach of nonneighboring Np chromophores forming an excimer and (2) a short corresponding to the fast adjustment of two neighboring Np chromophores in order to have the adequate parallel geometry. An additional decay time corresponding to the excimer decay was found to be present at all wavelengths. All the decay times were dependent on the water content of the mixture. An estimation of the two excimer forming rate constants values is made for the mixed media considered in this work. On the whole, using both steady-state and time-resolved fluorescence parameters, and by comparing data for a polymer with a small number of hydrophobes with a more highly modified one, it is possible in great detail to demonstrate how association is controlled by solvent quality for the hydrophobes and by the distance between hydrophobes

Supramolecular Structures of Poly(γ-benzyl-L-glutamate) Self-Assembled on Mica Surface

This article reports the results of structural studies of poly (-benzyl-L-glutamate) (PBLG) layers self-assembled from dilute solutions in organic solvents on mica surface. Polarized dynamic light scattering and atomic force microscopy were used to study polymer properties in solutions and on the surface. The hierarchy of self-assembly from PBLG solutions in different solvents was investigated as a function of polymer concentration and solvent polarity. We show that the surface–polymer interaction is suppressed in polar solvents that is interpreted in terms of suppressed charge–dipole interaction. The transformation of the PBLG surface structure occurs upon addition of different amounts of trifluoroacetic acid to polymer solution in dioxane. Rigid-rod PBLG molecules experience rod–globular transition while assembling on nonmodified mica from the very dilute solutions. A scheme is proposed describing different stages of PBLG fibrogenesis on a charged surface