This work reports a novel biocompatible and biodegradable arborescent amphiphilic polypept(o)ides-based polymer poly(γ-benzyl L-glutamate)-co-poly(γ-tert-butyl L-glutamate)-g-polysarcosine (P(BG-co-Glu(OtBu))-g-PSar) as a smart dual-responsive targeting drug vehicle. The synthesis pathway in this work highlighted the grafting reaction improvement of the polypeptides core and using polysarcosine (PSar) corona as a coating agent. The responsiveness of the polymer is caused by the pH sensitivity of the polypeptides and the reducible linker introduced between the core and corona. While adding the tripeptides arginine, glycine, and aspartate (RGD) as a ligand on the unimolecular micelles’ surface increases the targeting ability of the polymer. During the building of the arborescent, the coupling sites were controlled by using γ-tert-butyl L-glutamate (Glu(OtBu)-NCA) as a second monomer besides γ-benzyl L-glutamate (BG-NCA) since the deprotection conditions are different for Bz and tBu groups. Knowing the coupling sites provides accuracy in calculating the molecular weight (MW) of graft polymers since it facilitates the determination of the grafting yield (Gy). The arborescent unimolecular micelles were formulated by coating the hydrophobic core with PSar hydrophilic corona. The distribution of the coupling sites on the substrates in the last generation yielded end-grafted and randomly-grafted unimolecular micelles. A comparison between those micelles by DLS, TEM, and AFM revealed that the end-grafted micelles showed more uniformity in terms of morphology and size distribution. Also, the surface modification achieved via RGD addition increased the shape uniformity and contributed to avoiding the particles’ aggregation. The sizes and shapes of end-grafted unimolecular micelles match the drug delivery systems (DDSs) requirements. Doxorubicin (DOX) was encapsulated physically into the unimolecular micelles to study the drug loading capacity (DLC) and drug loading efficiency (DLE). The maximum DLC and DLE were 14% and 28% w/w, respectively. The drug release profiles were investigated in healthy- and cancer-mimicking media. The results showed that in cancer-mimicking microenvironment (low pH and high glutathione (GSH) content), the drug diffused out the micelles faster. In addition, a slower drug release was noticed for RGD decorated unimolecular micelles. Finally, the biocompatibility, cytotoxicity, and cellular uptake of the unimolecular micelles were studied. The obtained results were promising as the arborescent unimolecular micelles showed excellent biocompatibility; meanwhile, the DOX-loaded unimolecular micelles have good cytotoxicity compared to free DOX. RGD targeting ligand contributes to increasing the cellular uptake and supports the sustained release.

Membrane technology has great potential to complement traditional energy-intensive molecular separation processes such as distillation, with the advantage of low footprint generation. However, this would only be achieved with the development of better membranes able to operate in challenging conditions, including combinations of organic solvents, high temperatures, extreme pHs, and oxidative environments. This dissertation aims to use high-performance polymeric materials that can withstand temperatures of 120 °C in polar aprotic solvents like N,N-dimethylformamide as separation membranes, using different crosslinking strategies and alternative routes for commercially available material processing. The thesis will be divided into two main approaches. The first approach will start from soluble polyimides as precursors, with designed functionalities that allow post-membrane modifications, such as chemical crosslinking, thermal crosslinking, and thermal rearrangement to enhance the material's chemical resistance. The focus will be on the polyimide synthesis by an alternative one-step room-temperature polyhydroxyalkylation reaction. The chemical and thermal crosslinking take place without involving the imide bond, by incorporating a highly tunable functional group (isatin) in the synthesis of the materials. Propargyl as a pendant group will be used for the thermal crosslinking, and hydroxyl group for the thermal rearrangement. In all cases, the obtained membranes were stable in common organic solvents at 120 °C. The second approach will start from intrinsically solvent-resistant and commercially available poly(aryl ether ketone)s, turned into membranes by a closed-loop modification-regeneration strategy, to address long-term separations in organic solvents at high temperatures. We present for the first time porous poly(aryl ether ketone) flat-sheet and hollow fiber membranes prepared without the use of strong acids or high temperatures. Two methodologies are proposed. The developed strategies shall contribute toward avoiding the regular consumption of new materials and waste generation since the polymer used does not require crosslinking for its stability under organic solvents.

Poly-gamma-glutamic acid (γPGA), which is a biodegradable, non-immunogenic and unusual anionic amino-acid polymer consist of D- and L-glutamic acid units, was exploited for a wide array of useful applications. Bacillus are well known cellular system important for fermentation to synthesize γPGA, which is used as thickener, drugs carrier, cryoprotectant, humectant, biological adhesive, flocculants, or heavy metal absorbent. This study focused on the isolation of Bacillus spp. that is possible to produce γ-PGA from different soil samples from different places in Vietnam. Study the effect of precursors, temperature, carbon sources, times and pH on γ-PGA production. From 31 soil samples and 4 straws samples, strain 20.2 which produced the highest γ-PGA yields (riches 15.2 mg/ml), was identified as Bacillus sp. 20.2 by molecular biology method. The suitable conditions for growing of Bacillus sp. 20.2 strain to produce γ-PGA are at 37°C, pH 7 after 72 hours. Citric acid instead of glucose in a GSP medium is better for producing γ-PGA by strain Bacillus sp. 20.2. / Poly-gamma-glutamic acid (γ-PGA) là một polymer amino-acid gồm D và L-glutamic acid, có khả năng phân hủy sinh học, không gây miễn dịch, đã được ứng dụng rộng rãi trong công nghiệp, y học. Bacillus subtilis được biết đến là hệ thống tế bào ý nghĩa quan trọng trong quá trình lên men để tổng hợp γ-PGA. γ-PGA hòa tan trong nước, phân hủy sinh học và không độc đối với con người và môi trường. γ-PGA ổn định với nhiều protease vì các protease thường không nhận acid γ- glutamic (Obst et al., 2004). γ-PGA có cấu trúc đồng phân đơn giản, không gây miễn dịch. Do đó, γ-PGA đã được quan tâm ứng dụng trong các lĩnh vực như y học, công nghiệp thực phẩm, mỹ phẩm và đặc biệt là xử lý nước nhiễm kim loại nặng. Trong nghiên cứu này chúng tôi tập trung phân lập, tuyển chọn các chủng Bacillus có khả năng sinh tổng hợp PGA cao. Sau đó định danh và đánh giá khả năng sinh tổng hợp PGA từ chủng đã phân lập được. Kết quả cho thấy từ 34 mẫu rơm và đất, chúng tôi đã phân lập được chủng với mã số 20.2 có khả năng sinh PGA cao nhất đạt 15.2 mg/ml. Chủng này đã được định danh bằng phân tích trình tự gene 16S rRNA và thuộc loài Bacillus sp. Môi trường thích hợp sinh tổng hợp PGA là GSP ở điều kiện 37oC pH7 sau 72 giờ nuôi cấy.

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Ultrasound imaging systems are a safe and affordable imaging modality with the disadvantage of low spatial resolution, especially for assessing smaller vessels. However, with the implementation of super-resolution ultrasound imaging techniques, studies have shown promising results in achieving a resolution below the diffraction limit. Super-resolution ultrasound imaging techniques takes advantage of the point spread function to localize the centroid of the ultrasound contrast agents in an image. By superimposing thousands of these images, a super-resolved image of the localized and tracked contrast agents can be created, which presents an image where vessels down to a few micrometers can be resolved. The purpose of this master’s thesis was to implement super-resolution ultrasound imaging, test different localization methods and analyze them by using different ultrasound contrast agent concentrations. Grayscale ultrasound images were acquired using the Verasonics system for three different microbubble concentrations. The super-resolution ultrasound imaging program was executed on the grayscale images using three different localization methods, Gaussian fit, No-shift and Interpolation based scheme. The microbubbles were localized and tracked over several frames to create a super-resolved image which had the pixel resolution of a 10th of the wavelength. Significant improvements were demonstrated in the super-resolved images compared to the grayscale images. The higher microbubble concentrations resulted in a higher number of localized and tracked microbubbles. While the low concentration exhibited lower values. Comparing the methods, Gaussian fit and No-shift detected higher number of microbubbles than the method Interpolation. Although further analysis is needed, the thesis concluded that using Gaussian fit as a localization method and higher microbubble concentrations, a super-resolved image can be produced even if the program is tested on fewer images. / Ultraljudsavbildning är en säker och billig avbildningsmodalitet med en låg spatial upplösning, framför allt vid avbildning av mindre kärl. Men med implementering av ultraljudsavbildningstekniker med superupplösning har studier visat lovande resultat för att uppnå en upplösning under diffraktionsgränsen. Ultraljudsavbildningstekniker med superupplösning utnyttjar punktspridningsfunktionen för att lokalisera ett ultraljudskontrastmedels centerpunkt i en bild. Genom att överlagra tusentals av dessa bilder skapas en superupplöst bild av det lokaliserade och spårade kontrastmedlet. Med hjälp av superupplösta bilden kan kärl som är några mikrometer urskiljas. Syftet med denna masteruppsats var att implementera ultraljudsavbildning med superupplösning, testa olika lokaliseringsmetoder och analysera de genom att använda olika koncentrationer av mikrobubblor. Gråskale ultraljudsbilder samlades in med hjälp av Verasonics systemet för tre olika koncentrationer av mikrobubblor. Superupplösningsprogrammet var exekverad på gråskalebilderna för tre olika lokaliseringsmetoder, Gaussian fit, No-shift och Interpolation based scheme. Mikrobubblorna lokaliserades och spårades över flera bilder för att skapa en superupplöst bild vilket hade en tiondel av våglängden som pixelupplösning. Resultatet presenterade en märkbar förbättring i de superupplösta bilderna jämfört med gråskalebilderna. De högre koncentrationerna med flera mikrobubblor resulterade i ett högre antal lokaliserade och spårade mikrobubblor, medan den lägre koncentrationen gav färre lokaliserade mikrobubblor. Metoderna Gaussian fit och No-shift detekterade flera mikrobubblor än metoden Interpolation. Slutsatsen visade att användningen av lokaliseingsmetoden Gaussian fit med högre koncentrationer av mikrobubblor ger en superupplöst bild även om programmet exekveras på färre bilder.

Lim klassificeras som ett ämne som kan hålla ihop två ytor så att de motstår separation. Dagens lim kan anpassas efter vilken applikation de ska användas till och kan ha ett stort antal olika egenskaper. De fysikaliska och kemiska egenskaperna av limmet är de viktigaste faktorerna för att bilda en bra limbindning. I stort sett alla syntetiska lim består idag av polymerer, varav de flesta är petroleumbaserade. För att skapa ett mer miljövänligt alternativ undersökte denna studie tillämpningen av poly(3-hydroxibutyrat- co-3-hydroxivalerat), PHBV med 36 eller 56 vikt% HV, som huvudkomponent i ett lim. Huvudfokus ligger på hur väl PHBV är lämpligt för användning som lim och hur olika tillsatser kan förbättra dess egenskaperna. Flera olika limblandningar innehållande PHBV, mjukgörare (sebacinsyra, dimetylsebacat, etylbutanoat eller tributylcitrat) och förtjockningsmedel (Abalyn eller Foralyn) skapades och undersöktes. Ett single lap skjuvtest utfördes med kopieringspapper, filterpapper och träpinnar som vidhäftningsmaterialet, medan ett avskalningstest undersökte användningen av kopieringspappersetiketter och plastetiketter på en glasflaska samt frukt.  Båda testen visar att kopieringspapper har de mest lovande egenskaperna som en adherent för användningen av ett PHBV-baserat lim, både för PHBV innehållande 36 vikts% och 56 vikts% HV. Denna slutsats kunde dras då kopieringspapperet påvisade den starkaste bindningen med limmet. Ren PHBV uppvisade lovande häftstyrka och vidhäftning som ett smältlim. Tillsatsen av sebacinsyra tillsammans med Abalyn eller dimetylsebacat med Foralyn ökade limmets häftstyrka ytterligare. Vi fann också att lim som skapats med PHBV med 36 vikt% HV ger bättre hållfasthetsegenskaper. Framtida arbete innefattar mer exakta mätmetoder för att bestämma egenskaperna hos limblandningarna. / An adhesive is classified as a substance that holds two surfaces together and resists separation. Today’s adhesives can be modified according to various application demands, obtaining a large variety of properties. The most important factors of forming a good adhesive bond are the physical and chemical properties. Essentially all synthetic adhesives consist of polymers, most of them being petroleum-based. To obtain a more environmentally friendly option, this study investigated the use of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV with 36 or 56 wt% HV, as the main component in an adhesive. The main focus was to investigate on how well PHBV is suited for use as an adhesive and how different additives can improve the adhesive properties. Several different adhesive formulations containing PHBV, plasticizers (sebacic acid, dimethyl sebacate, ethyl butyrate, or tributyl citrate) and tackifiers (Abalyn or Foralyn) were created and investigated using various tests, such as single lap shear test, peel test, tackiness determination, optical analysis, and application testing. Single lap shear tests were performed using printing paper, filter paper, and wooden sticks as adherents, while peel tests explored the use of printing paper labels and plastic labels on a glass bottle and on fruit. It was determined that two PHBV adhesives, containing 36 wt% and 56 wt% of HV, performed best using printing paper as adherent. This conclusion could be drawn based on the good interaction between the adherent and the adhesive, thereby creating a strong bond. Pure PHBV with 36 or 56 wt% showed promising strength and tackiness properties as a hot-melt adhesive. The addition of sebacic acid together with Abalyn or dimethyl sebacate with Foralyn further increased the adhesive’s strength. It was also found that adhesive formulations created using a PHBV with a lower amount of HV (around 36 wt% of HV) yields better strength properties when used as an adhesive for paper labels. Future work involves more precise measurement methods to determine the properties of the adhesive formulations.

The results described in this dissertation have demonstrated several alternative proton exchange membranes (PEM) for hydrogen-air and direct methanol fuel cells (DMFC) that perform as well or better than the state of the art Nafion perfluorosulfonic acid membrane. Direct aromatic nucleophilic substitution polycondensations of disodium 3,3′ S-disulfonate-4,4′ S-difluorodiphenylsulfone (SDFDPS), 4,4′ S-difluorodiphenylsulfone (DFDPS) (or their chlorinated analogs, SDCDPS, DCDPS) and 4,4′ S-thiobisbenzenethiol (TBBT) in the presence of potassium carbonate were investigated. Electrophilic aromatic substitution was employed to synthesize the SDFDPS or SDCDPS comonomers in high yields and purity. High molecular weight disulfonated poly(arylene thioether sulfone) (PATS) copolymers were easily obtained using the SDFDPS monomers, but in general, slower rates and a lower molecular weight copolymer was obtained using the analogous chlorinated monomers. Tough and ductile membranes were solution cast from N,N-dimethylacetamide for both series of copolymers. The degrees of disulfonation (20-50%, PATS 20-50) were controlled by varying the ratio of disulfonated to unsulfonated comonomers. Composite membranes were prepared by homogeneous solution blending the copolymers with phosphotungstic acid (PTA) in dimethylacetamide (DMAc). The composite PATS membranes exhibited moderate PTA molecule water extraction after acidification treatments performed at either room or boiling temperatures. The membranes containing HPA showed improved conductivity at high temperatures (120 °C) and low relative humidities when compared to the pure copolymers. Molecular weight of the copolymers plays a critical role in the overall copolymer physical behavior. It is well known that molecular weight has an enormous impact on practically all of the physical properties of polymeric systems. This dissertation discusses the influence of molecular weight on the characteristics of a specific family of PEM PATS copolymers. This study elucidated that the lower molecular weight materials did indeed behave differently than the higher molecular weight copolymers. Specifically, the water uptake and permeability to methanol decreased with increasing molecular weight. Furthermore, the fully hydrated mechanical properties also improved with molecular weight. The synthesis and fabrication of 45 mole percent disulfonated poly(arylene ether phenyl phosphine oxide diphenyl sulfone) terpolymer-heteropolyacid (HPA) composite membranes and membrane electrode assemblies were chosen for detailed investigation. A series of 45 mole percent disulfonated biphenol-based poly(arylene ether phenyl phosphine oxide diphenyl sulfone) terpolymers (BPSH45-PPO) were also synthesized by nucleophilic aromatic substitution polymerizations. The level of disulfonation was constant at 45 mole percent providing a compromise between high conductivity at low humidity and reasonable mechanical properties in liquid water. The amounts of 4,4′-difluorodiphenyl phenyl phosphine oxide comonomer incorporated into the terpolymer backbone were precisely controlled from 0-50 mole percent relative to the 4,4′-dihalodiphenyl sulfone. Phosphine oxide moieties were employed to enhance the interactions with the PTA relative to the pure copolymer. The composite BPSH45-PPO membranes exhibited lower HPA molecule water extraction after acidification at room and boiling temperatures, which was ascribed to the strong hydrogen and polar interactions between the phosphine oxide moiety and functional groups on the HPA. The membranes containing HPA displayed improved conductivity at high temperatures and low relative humidities when compared to the pure terpolymer samples. The increase of proton conductivity was attributed to the water retention characteristics of the HPA molecules, which allowed enhanced mobility of the protons even at lower humidification levels, providing superior hydrogen-air fuel cell performance. The effect of hexafluoroisopropylidene bisphenol (6FBP) incorporation into 45 mole percent disulfonated poly(arylene ether sulfone) copolymers was investigated. This novel series of directly disulfonated poly(arylene ether sulfone) copolymers with various mole ratios of the 6FBP were synthesized in high molecular weight. The levels of fluorination within the statistically random copolymer architecture were varied from 0-100 mole percent using 6FBP and the correct stoichiometric amount of 4,4′-biphenol. The 6FBP monomer was introduced to decrease the water swelling and improve bonding characteristics with Nafion-bonded electrodes. Indeed, water uptake decreased with increasing incorporation of the 6FBP monomer into the terpolymer. This suggested that the hydrophobic fluorinated material aided in water repulsion of the system. Proton conductivity decreased slightly as the amount of fluorination increased, which was interpreted to be due to the decrease in the ion-exchange capacity. High temperature hydrogen/air fuel cell experiments indicated better Nafion-bonded electrode adhesion for the partially fluorinated materials, as depicted by high temperature (120 °C) and low humidity (50% RH) hydrogen-air fuel cell performance. Investigations into polymeric electromechanical transducers were based on poly(arylene sulfone) ion-exchange membranes bonded between two conductive metal layer electrodes. Imposed deformations and small electric fields allowed similar explorations of both sensing and actuation applications. These copolymers produced larger sensitivities than the benchmark Nafion systems, which was interpreted as being due to their higher hydrated moduli. Methodologies for better defining the morphology of the electrodes were identified to enhance the capacitance and effective interfacial area of the conductive electrodes. The new procedures afforded major improvements to performance and transduction. Transducer actuation at lower frequencies was improved by employing a new direct assembly electrode fabrication technique that suggested a strong correlation between the capacitance and charge motion. / Ph. D.