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Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This study involves the analysis of crystallization and melting behavior of polymers in solution, using Solution crystallization by laser light scattering (Scalls) as analytical tool. Various other techniques such as differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS) were used for further characterization of the polymer materials. For the first time the solution behavior (crystallization and dissolution kinetics) of two biopolymers namely, poly(lactic acid) (PLA) and poly(butylene succinate) (PBS), was monitored by Scalls. Non-isothermal solution crystallization and dissolution behavior of both enantiomers (D and L) PLA and their blends were studied. It was found that addition of the D- enantiomer (PDLA) to the L- enantiomer (PLLA) in solution resulted in the formation of stereocomplex crystals (SC) and the nucleation-effect of the crystals were intensified with an increase in PDLA content leading to an earlier onset of crystallization and increased crystallization peak area. DSC analysis confirmed the formation of SC during solution crystallization. Overall, results obtained by Scalls provided promising information regarding PLA crystallization kinetics which significantly influences practical applications of this biopolymer. Binary blends consisting of PLLA and PBS were prepared in various blend ratios. Scalls was used to investigate the non-isothermal crystallization and melting behavior of these PLLA/PBS blends from dilute solutions. Addition of PBS up to 30 wt% increased crystallization temperatures of PLLA through a nucleation effect in the molten PBS state. Results indicated that the crystallization rate of PLLA can be improved by additions of small amounts of PBS, and this is of significant interest for practical applications due to the low crystallization rate that PLLA is known to exhibit. DSC thermograms showed an increase in PLLA crystallization exotherm at PBS loadings below 50 wt%, providing further evidence of the enhancement in PLLA crystallization kinetics. A series of linear polyethylene samples with varying molecular weights were studied by Scalls. The effect of molecular weight (Mw) on the solution crystallization temperature (Tc) were monitored and compared to literature where the conventional Crystaf technique was used. Experimental Scalls data correlated well with reported theoretical models. Dissolution studies were also done to study the effect of Mw on the solution melting temperature (Tm) and for the first time, an equation was generated to model solution melting temperatures of linear polyethylenes in Scalls. The solution behavior of a PE-1-octene linear low-density polyethylene (LLDPE) copolymer in a range of solvents including trichlorobenzene (TCB), ortho-dichlorobenzene (o-DCB), decalin and xylene were successfully studied. Scalls allowed for rapid analysis of crystallization and dissolution during a single experiment and offered clearer insight into crystallization kinetics when using different solvents for fractionation. Peak temperatures for analyses in TCB and o-DCB were almost identical but remarkably different to those observed when decalin and xylene was used. The study revealed that solvent type plays an important role in the solution behavior of polymers as well as ultimately the interpretation of these results. / AFRIKAANSE OPSOMMING: Hierdie studie behels die ontleding van kristallisasie en smelt gedrag van polimere in oplossing, met behulp van Oplossing kristallisasie deur laser lig verstrooiing (Scalls) as analitiese instrument. Verskeie ander tegnieke soos differensiële skandeer kalorimetrie (DSC), fourier-tranform infrarooi spektroskopie (FTIR) en dinamiese lig verstrooiing (DLS) was gebruik word vir verdere Karakterisering van die polimeer materiaal. Vir die eerste keer is die oplossingsgedrag (kristallisasie en smelting kinetika) van twee biopolimere naamlik, poli(melksuur) (PLA) en poli(butileen suksinaat) (PBS), deur Scalls gemonitor. Nie-isotermiese oplossing kristallisasie en smelt gedrag van beide enantiomere (D en L) van PLA en hul mengsels was ge-analiseer. Daar is gevind dat byvoeging van die D-enantiomeer (PDLA) tot die L-enantiomeer (PLLA) in oplossing gelei het tot die vorming van stereokompleks kristalle (SC) en die nukleasie-effek van die kristalle is versterk met 'n toename in PDLA inhoud wat gelei het tot 'n vroeër aanvang van kristallisasie en toename in kristallisasie piek-area. DSC analise het die vorming van SC gedurende oplossing kristallisasie bevestig. Algeheel, die resultate wat verkry was deur Scalls het belowende inligting oor PLA kristallisasie kinetika verskaf wat aansienlik praktiese toepassing van hierdie biopolimeer beïnvloed. Binêre mengsels bestaande uit PLLA en PBS was voorberei in verskillende mengsel verhoudings. Scalls was gebruik om die nie-isotermiese kristallisasie en smelt gedrag van hierdie PLLA/PBS mengsels, vir die eerste keer, in verdunde oplossings te ondersoek. Byvoeging van PBS tot 30 wt% het ‘n toename in kristallisasie temperature van PLLA veroorsaak deur 'n nukleasie-effek in die gesmelte PBS toestand. Resultate dui aan dat die tempo van PLLA kristallisasie versnel kan word deur byvoegings van PBS in klein hoeveelhede, en dit is van beduidende belang vir praktiese toepassings weens die lae kristallisasie-tempo waarvoor PLLA bekend is. DSC termogramme het 'n toename in PLLA kristallisasie eksoterm aangedui by PBS inhoud onder 50 wt%, wat 'n verdere bewys is van die verbetering in PLLA kristallisasie kinetika. 'n Reeks lineêre poliëtileen monsters met wisselende molekulêre massas was met Scalls geanaliseer. Die effek van molekulêre massa (Mw) op die oplossing kristallisasie temperatuur (Tc) was gemonitor en vergelyk met literatuur waar die konvensionele Crystaf tegniek gebruik is. Eksperimentele Scalls data het goed gekorreleer met gerapporteerde teoretiese modelle. Smelting studies is ook gedoen om die effek van Mw op die oplossing smelt temperatuur (Tm) te bestudeer en vir die eerste keer, is 'n vergelyking ge-genereer vir die modellering van oplossing smelt temperature van lineêre poliëtileen met behulp van Scalls. Die oplossing-gedrag van ‘n PE-1-okteen lineêre lae-digtheid poliëtileen (LLDPE) kopolimeer was suksesvol bestudeer in 'n verskeidenheid oplosmiddels, insluitend trichlorobenseen (TCB), ortodichlorobenseen (o-DCB) , decalin en xileen. Scalls het toegelaat vir vinnige analise van die kristallisasie en smelting in 'n enkele eksperiment en het dieper insig gegee oor die kristallisasie kinetika tydens fraksionering met die gebruik van verksillend oplosmiddels. Piek temperature vir analises in TCB en o-DCB was byna identies, maar merkwaardig verskillend van dié wat waargeneem was in die geval waar decalin en xileen gebruik was. Hierdie studie het getoon dat die tipe oplosmiddel 'n belangrike rol speel in die oplossing-gedrag van polimere en uiteindelik asook die interpretasie van hierdie resultate. Verder blyk Scalls na ‘n nuttige metode vir die ontleding van polimere in oplossing te wees.

Three projects are described in this thesis that combine microfabrication techniques with optical micromanipulation. The aim of these projects is to use expertise in microlithography and optical tweezing to create new tools for Lab-on-Chip devices. The first project looks at the creation of microgears that can be moved using an optical force. The microgears include one dimensional photonic crystal that creates birefringence. This allows the transfer of angular momentum from a circularly polarised light beam to the microgear, making them spin. The microgears are simulated, fabricated and tested. Possible biological applications are suggested. The second project looks at creating microchannels to perform micromanipulation experiments in. Different methods of fabricating the microfluidic channels are compared, and the resulting chambers are used to find the maximum flow rate an optical sorting experiment can be performed at. The third project involves using a thin photoconductive layer to allow the optical control of an electrical force called dielectrophoresis. This light induced dielectrophoresis (LIDEP) allows similar control to optical tweezing but requires less irradiance than optical tweezing, allowing control over a larger area with the same input optical power. A LIDEP device is created and experiments to measure the electrical trap size that is created with a given optical spot size are performed. These three projects show different microfabrication techniques, and highlight how well suited they are for use in optical manipulation and microfluidic experiments. As the size of objects that can be optically manipulated matches well with the size of objects that can be created with microfabrication, it seems likely that many more interesting applications will develop.

Peng Shufu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by Woo Ka Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 61-63). / Abstract --- p.i / Acknowledgment --- p.ii / Contents --- p.iii / Abbreviations --- p.iv / List of Figures --- p.vii / List of Tables --- p.ix / Chapter 1 --- Introduction --- p.1 / Chapter 2. --- Theoretical background / Chapter 2.1 --- Static light scattering for homopolymer --- p.5 / Chapter 2.2 --- Static light scattering for copolymer --- p.16 / Chapter 2.3 --- Dynamic light scattering --- p.19 / Chapter 2.4 --- Modified method for copolymer --- p.28 / Chapter 3. --- Experimental / Chapter 3.1 --- Preparation of PET-PCL --- p.31 / Chapter 3.2 --- Preparation of solution for LLS --- p.31 / Chapter 3.3 --- Refractive index increment measurement --- p.32 / Chapter 3.4 --- Laser light scattering instrumentation --- p.35 / Chapter 4. --- Results and Discussion --- p.36 / Chapter 5. --- Conclusion --- p.60 / Chapter 6. --- References --- p.61

by Shui-Qin Zhou. / Publication date from spine. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 152-157). / Acknowledgments --- p.i / Abstract --- p.ii / Contents --- p.vi / Abbreviation --- p.viii / List of Figures --- p.xi / List of Tables --- p.xvi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1. --- Project's Significance --- p.1 / Chapter 1.2. --- Research background.....................................: --- p.1 / Chapter 1.2.1. --- Linear PNIPAM chains in aqueous solution --- p.2 / Chapter 1.2.1.1. --- Origins of the LCST --- p.2 / Chapter 1.2.1.2. --- Experimental studies --- p.4 / Chapter 1.2.2. --- PNIPAM gels --- p.9 / Chapter 1.2.2.1. --- Origins of the volume phase transition --- p.10 / Chapter 1.2.2.2. --- Experimental studies --- p.11 / Chapter 1.2.3. --- Surfactant effects --- p.13 / Chapter 1.3. --- The objective of the project --- p.15 / Chapter 1.4. --- Experimental difficulties --- p.17 / Chapter 2. --- Basic Theory --- p.20 / Chapter 2.1. --- Laser light scattering (LLS) --- p.20 / Chapter 2.2. --- Polymer chains in solution --- p.23 / Chapter 2.3. --- Swollen polymer gels --- p.27 / Chapter 3. --- Results and Discussion --- p.32 / Chapter 3.1. --- Linear PNIPAM chains --- p.32 / Chapter 3.1.1. --- D = kDM-αD for PNIPAM in THF and water --- p.32 / Chapter 3.1.2. --- Coil-to-globule transition of single PNIPAM chains in water --- p.46 / Chapter 3.1.3. --- Additional chain-conformation broadening of the line-width distribution in dynamic LLS --- p.64 / Chapter 3.1.4. --- Internal motions of long linear PNIPAM chains --- p.72 / Chapter 3.1.5. --- Structural model of spherical water/AOT/n-hexane microemulsion --- p.80 / Chapter 3.2. --- Spherical PNIPAM microgels --- p.94 / Chapter 3.2.1. --- Volume phase transition of PNIPAM microgels --- p.94 / Chapter 3.2.2. --- Internal motions of short PNIPAM subchains inside the gel networks --- p.107 / Chapter 3.2.3. --- Surfactant effects on the volume phase transition --- p.113 / Chapter 3.2.4. --- Swelling and drying kinetics of a very thin PNIPAM gel film --- p.129 / Chapter 4. --- Conclusions --- p.141 / Chapter 5. --- Experimental --- p.145 / Chapter 5.1 --- Sample preparation --- p.145 / Chapter 5.2 --- Physical measurement --- p.149 / Chapter 6. --- References --- p.152

by Gao Yibing. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

In Chapter 1, theories cited background of these studies as well as chemical synthesis methods used are introduced. / In Chapter 2, theories of static and dynamic light scattering (LLS) as well as details of the LLS instrumentation are introduced, especially the application of LLS to polymer solutions. / In Chapter 3, we present the study of the self-assembly of oligo( p-phenyteneethynylene)-based coil-rod-coil and rod-coil-rod triblock copolymers in the solvent mixture of toluene and hexane by using a combination of static and dynamic laser light scattering. UV-vis spectroscopy and fluorescence spectroscopy. Our results reveal that the aggregation in the solvent mixture is strongly influenced by the triblock copolymer structure. For the coil-rod-coil (PS-OPE-PS) triblock copolymer, small well-defined aggregates are formed in the solvent mixture with different toluene/hexane ratios. The coiled PS blocks entangle with the OPE block to restrict possible pi-pi stacking and make the OPE chain backbone more planar. The red-shift in the UV-vis and fluorescence spectra indicates the formation of 3-type aggregates. The rod-coil-rod (OPE-PS-OPE) triblock copolymer chains form large "disk-like" micelles with an ordered OPE core and a collapsed PS shell. The blue-shift in the UV-vis and fluorescence spectra shows the formation of H-type aggregates; namely, the OPE block in the core are parallel to each other so that there is stronger interchain pi-pi interaction. / In Chapter 4, we present the study of the aggregation of C60-PEO-C 60 chains in the chloronaphthalene/benzene solvent mixture with different ratios by using a combination of static and dynamic laser light scattering. Chloronaphthalene is a good solvent for C60 but a poor solvent for the PEO chain. On the other hand, benzene is a good solvent for the PEO chain but a poor solvent for Co. Individual polymer chains or small micelles coexist with large aggregates in solvent mixture. Our results show that the structures of the aggregates strongly depend on the composition of the solvent mixtures, which reflects in different ratios of <Rg>/<R h>, where <Rg> and <Rh> are z-average root-mean-square radius of gyration and hydrodynamic radius, respectively. / In Chapter 5, we present a study of reversible formation and decomposition of star polymer clusters. First, we synthesized 4-aim bromide-end star polystyrene chains by using atom transfer radical polymerization (ATRP), and then modified the end group from bromide to thiol since it can be slowly oxidized in air to induce the clustering among 4-arm star polystyrene chains. The clustering is reversible under a reduction condition. Such formation and fragmentation (decomposition) of the polymer clusters in toluene was followed by LLS. To induce the reduction, DTT was added. Our results reveal that in the clustering, the fast mode is attributed to the cooperative diffusion of individual 4-arm star polystyrene chains (unimers), while the slow mode is related to the diffusion of large clusters. In the fragmentation, the slow mode becomes fast and its intensity contribution decreases as the reduction time increases, reflecting the decreases of the size and the number of large polymer clusters. Our results suggest that the clusters fragmentation induced by thiol-functionalized 4-PS chains in toluene dilute solution follows the universal RLCA regime, but in a reversed fashion. / In this thesis, we did the following studies: (1) The association of two rod-coil triblock copolymers: polystyrene-oligo(p-phenyleneethynylene)-polystyrene (PS-OPE-PS) and oligo(p-phenyleneethynylene)-polystyrene-oligo( p-phenyleneethynylene) (OPE-PS-OPE) in a toluene/hexane mixture as well as of C60-Poly(ethylene oxide)-C60 in a chloronaphthalene/benzene mixture. (2) The formation and fragmentation of 4-arm-PS-SH cluster in toluene via the oxidization in air to form disulfide crosslink as well as the decomposition of the resultant cross-linked 4-arm star polystyrene clusters with reversible disulfide groups in toluene via reduction to thiol group by 2,3-dihydroxy-1,4-butanethiol (DTT). / Huo, Hong. / "August 2007." / Adviser: Chi Wu. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1037. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 109). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

by Kwan Chi Man Simon. / Abstract also in Chinese. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references. / Abstract --- p.i / Abstract (Chinese) --- p.iii / Acknowledgment --- p.iv / Contents --- p.v / Abbreviations --- p.viii / List of Figures --- p.xiv / List of Tables --- p.xvii / Chapter 1. --- Introduction --- p.1 / Chapter 2. --- Theoretical background --- p.4 / Chapter 2.1 --- Static laser light scattering --- p.5 / Chapter 2.2 --- Dynamic laser light scattering --- p.5 / Chapter 2.3 --- Gel Permeation Chromatography --- p.6 / Chapter 2.4 --- Chain Flexibility --- p.9 / Chapter 2.4.1 --- Flexible chains --- p.9 / Chapter 2.4.2 --- Stiff chains --- p.12 / Chapter 2.5 --- Calibration between translational diffusion coefficient D and molar mass M --- p.14 / Chapter 2.5.1 --- Conversion between line-Width and molar Mass distributions --- p.14 / Chapter 2.5.2 --- Using a set of Narrowly Distributed Standards --- p.15 / Chapter 2.5.3 --- Using Two or More Broadly Distributed Samples --- p.16 / Chapter 2.6 --- "Calibration by off-line GPC, Static and Dynamic LLS" --- p.16 / Chapter 2.7 --- References --- p.19 / Chapter 3. --- Experimental --- p.21 / Chapter 3.1 --- Laser Light Scattering Instrumentation --- p.21 / Chapter 3.2 --- Refractive index increment measurement --- p.23 / Chapter 3.3 --- Gel permeation chromatography --- p.24 / Chapter 3.4 --- References --- p.25 / Chapter 4. --- Laser Light Scattering Studies of Soluble High Performance Fluorine- containing Polyimides --- p.26 / Chapter 4.1 --- Introduction --- p.26 / Chapter 4.2 --- Sample Preparation --- p.28 / Chapter 4.3 --- Results and Discussion --- p.28 / Chapter 4.4 --- Conclusion --- p.40 / Chapter 4.5 --- References --- p.42 / Chapter 5. --- Characterization of novel optically active conjugated polyarylenes and poly(aryleneethynylene)s by a combination of Laser Light Scattering and Gel Permeation Chromatography --- p.45 / Chapter 5.1 --- Introduction --- p.45 / Chapter 5.2 --- Sample Preparation --- p.48 / Chapter 5.3 --- Results and Discussion --- p.48 / Chapter 5.4 --- Conclusion --- p.56 / Chapter 5.5 --- References --- p.61 / Appendix --- p.62 / Chapter A.1 --- Static laser light scattering --- p.62 / Chapter A.1.1 --- Scattering from a small particle --- p.62 / Chapter A. 1.2 --- Scattering from a large particle --- p.62 / Chapter A. 1.3 --- Scattering by macroscopic systems and Theory of Fluctuations --- p.65 / Chapter A.1.3.1 --- Scattering by gases and liquids --- p.67 / Chapter A. 1.4 --- Scattering by solutions of small molecules --- p.68 / Chapter A. 1.4.1 --- Scattering from polymer solution --- p.70 / Chapter A.2 --- Dynamic laser light scattering --- p.71 / Chapter A.2.1 --- Line-width measurement --- p.75 / Chapter A.2.2 --- Data analysis --- p.77