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A thin polymer bilayer film was transformed into micro- and nano-tubes using strain driven self-rolling phenomena of polystyrene (PS)/poly (4-vinyl pyridine) (P4VP) film. Polymer bilayer was produced by consecutive deposition of PS and P4VP, from toluene and chloroform solutions, respectively, by dip-coating technique. The object formation proceeds from a opening in the film made by photolithography or by mechanical scratching followed by immersion of patterned sample in dodecylbenzene sulfonic acid (DBSA) solution. DBSA forms supramolecular complexes with pyridine rings of P4VP and increases the specific volume of the polymer. Since the solution is neutral to PS layer, bilayer film develops strain due to unequal swelling of polymers in solution of DBSA and hence the film bends and scrolls in order to minimize its free energy and form tubes. The length of the tubes and the direction of rolling are determined by mechanical patterning of the film. UV-photolithography is used to fabricate patterns of polymer bilayer in order to create tube in a precise manner. The kinetics of the tube formation was studied with respect to acidity of the solution and UV dose. Rate of rolling increased with the acidity of the solution. Tube diameter and rate of rolling decreased with the increase of the UV exposure time. Films with 2-dimensional gradients of layer thicknesses were prepared to study a broad range of parameters in a single experiment. Furthermore, polymer micro-toroids and triangles were also fabricated using self-rolling approach of PS/P4VP layer. Moreover, the kinetics of toroid formation is also studied in the present work. The equilibrium dimensions of toroid are determined by the balance of the bending and the stretching energies of the film. The width of the rolled-up bilayer is larger for the films with higher values of the bending modulus and smaller values of the effective stretching modulus. Moreover, self-rolling phenomena of polymer layer was also explored as a template to fabricate metal, ceramic and metal/ceramic hybrid tube. In order to fabricate metallic and V bimetallic tube, the cross-linked polymer film is capped by metallic layer. After rolling, polymer template is removed by pyrolysis resulting in pure metal microtubes. The fabrication of silica and silica/gold hybrid tubes of high aspect ratio is also demonstrated. Polydimethylsiloxane (PDMS) is used as a precursor of the silica and it is converted into silica by pyrolysis at high temperature. Entire polymer moiety is also removed at this temperature. In order to fabricate hybrid tube of silica with gold, a thin gold layer is deposited on the polymer layer by physical vapour deposition. Self-rolling of polymer bilayers is a very convenient approach for interfacing the interior of microtubes with external electrical circuits and it can be used in particular for creating devices as micro-bubble generators exploiting electrolytic decomposition of fluids. A demonstration of microbubble generation inside the polymer tube is shown in this work. Possibility to functionalize the hidden walls of the tubes is one of the major advantages of the self-rolling approach. One can modify the surface of the film prior to rolling by magnetron sputtering of metal and upon rolling, tube and toroids with metallized inner surface could be obtained. The tube and toroids with metallic inner surface are promising for the future research as IR-frequency range resonators. Polymer and metallic microtubes fabricated by self-rolling approach may find applications in such fields as IR-waveguiding, microfluidics, enzyme bi-reaction, chemical and biochemical sensing. The silica and silica/gold hybrid tubes have potential use in optoelectronic devices and in catalytic applications.

A thin polymer bilayer film was transformed into micro- and nano-tubes using strain driven self-rolling phenomena of polystyrene (PS)/poly (4-vinyl pyridine) (P4VP) film. Polymer bilayer was produced by consecutive deposition of PS and P4VP, from toluene and chloroform solutions, respectively, by dip-coating technique. The object formation proceeds from a opening in the film made by photolithography or by mechanical scratching followed by immersion of patterned sample in dodecylbenzene sulfonic acid (DBSA) solution. DBSA forms supramolecular complexes with pyridine rings of P4VP and increases the specific volume of the polymer. Since the solution is neutral to PS layer, bilayer film develops strain due to unequal swelling of polymers in solution of DBSA and hence the film bends and scrolls in order to minimize its free energy and form tubes. The length of the tubes and the direction of rolling are determined by mechanical patterning of the film. UV-photolithography is used to fabricate patterns of polymer bilayer in order to create tube in a precise manner. The kinetics of the tube formation was studied with respect to acidity of the solution and UV dose. Rate of rolling increased with the acidity of the solution. Tube diameter and rate of rolling decreased with the increase of the UV exposure time. Films with 2-dimensional gradients of layer thicknesses were prepared to study a broad range of parameters in a single experiment. Furthermore, polymer micro-toroids and triangles were also fabricated using self-rolling approach of PS/P4VP layer. Moreover, the kinetics of toroid formation is also studied in the present work. The equilibrium dimensions of toroid are determined by the balance of the bending and the stretching energies of the film. The width of the rolled-up bilayer is larger for the films with higher values of the bending modulus and smaller values of the effective stretching modulus. Moreover, self-rolling phenomena of polymer layer was also explored as a template to fabricate metal, ceramic and metal/ceramic hybrid tube. In order to fabricate metallic and V bimetallic tube, the cross-linked polymer film is capped by metallic layer. After rolling, polymer template is removed by pyrolysis resulting in pure metal microtubes. The fabrication of silica and silica/gold hybrid tubes of high aspect ratio is also demonstrated. Polydimethylsiloxane (PDMS) is used as a precursor of the silica and it is converted into silica by pyrolysis at high temperature. Entire polymer moiety is also removed at this temperature. In order to fabricate hybrid tube of silica with gold, a thin gold layer is deposited on the polymer layer by physical vapour deposition. Self-rolling of polymer bilayers is a very convenient approach for interfacing the interior of microtubes with external electrical circuits and it can be used in particular for creating devices as micro-bubble generators exploiting electrolytic decomposition of fluids. A demonstration of microbubble generation inside the polymer tube is shown in this work. Possibility to functionalize the hidden walls of the tubes is one of the major advantages of the self-rolling approach. One can modify the surface of the film prior to rolling by magnetron sputtering of metal and upon rolling, tube and toroids with metallized inner surface could be obtained. The tube and toroids with metallic inner surface are promising for the future research as IR-frequency range resonators. Polymer and metallic microtubes fabricated by self-rolling approach may find applications in such fields as IR-waveguiding, microfluidics, enzyme bi-reaction, chemical and biochemical sensing. The silica and silica/gold hybrid tubes have potential use in optoelectronic devices and in catalytic applications.

Les deux systèmes de création d’une contrainte dans les films polymériques ont été développés, chacun répondant à un gradient de gonflement du polymère dans la direction normale au film. Ce gonflement peut être provoqué soit par la présence d’un gradient de densité de réticulation dans la direction normale à la surface (films de poly(4-vinylpyridine) réticulés par UV ou dans les films de chitosan réticulés thermiquement et ioniquement ; ou soit par une pénétration asymétrique de vapeur de solvant dans le film (ici le polydiméthylsiloxane oxydé en surface). Un troisième système polymérique auto-enroulant a également été réalisé par la création d’une contrainte permanente au sein du film de polydiméthylsiloxane, grâce à l’extraction sélective d’un additif non-réticulé, l’huile de silicone. Un modèle théorique du processus d’auto-enroulement, basé sur la théorie linéaire d’élasticité a ainsi pu être proposé. / Two systems of stress creation in the polymer films were developed, each based on the swelling gradient in the direction normal to the film. This swelling may be caused either by the presence of a crosslinking density gradient in the direction normal to the surface (poly (4-vinylpyridine film) crosslinked by UV or in the thermally or ionically crosslinked chitosan films; or by asymmetric penetration of solvent vapor in the film (here polydimethylsiloxane surface-oxidized). A third self-rolling polymeric system has also been realized by the creation of a permanent strain in the polydimethylsiloxane film by selective extraction of a non-cross-linked additive, silicone oil. A theoretical model of self-rolling process based on the linear theory of elasticity has been proposed.

This thesis is focused on the design and development of an approach, allowing the fabrication of biocompatible/biodegradable self-rolled polymer tubes, which are sensitive to stimuli at physiological conditions, can be homogenously filled with cells and are able to self-assemble into a complex 3D construct with uniaxially aligned pores. These constructs are aimed to recreate the microstructure of tissues with structural anisotropy, such as of muscles and bones. The approach consists of two steps of self-assembly. As a first step, cells are adsorbed on the top of an unfolded bilayer; triggered rolling results in a parallel encapsulation of cells inside the tubes. As a second step, the formed self-rolled tubes with encapsulated cells can be assembled in a uniaxial tubular scaffold. Three polymer systems were designed and investigated in the present work in order to allow triggered folding of the bilayer. These systems allow either reversible or irreversible tube formation. The possibility to encapsulate microobjects inside self-rolled polymer tubes was demonstrated on the example of silica particles, yeast cells and mammalian cells. At conditions when bilayer film is unfolded, particles or cells were deposited from their aqueous dispersion on the top of bilayer. An appropriate change of conditions triggers folding of the bilayer and results in encapsulation of particles or cells inside the tubes. One way swelling of an active polymer allows irreversible encapsulation of cells in a way that tubes do not unroll and cells cannot escape. It was demonstrated that encapsulated cells can proliferate and divide inside the tubes for a long period of time. Since used polymers are optically transparent, encapsulated cells can be easily observed using optical and fluorescent microscopy. Reversible swelling of an active polymer provides the possibility to release encapsulated objects. It was demonstrated that in aqueous media microtubes possessing small amount of negatively charged groups on external walls self-assemble in the presence of oppositely charged microparticles that results in a formation of 3D constructs. In obtained aggregates tubes and therefore pores were well-aligned and the orientation degree was extremely high. Moreover, the approach allows the design of porous materials with complex architectures formed by tubes of different sorts. The assembly of cell-laden microtubes results in a formation of uniaxial tubular scaffold homogeneously filled with cells. The results presented in this work demonstrate that the proposed approach is of practical interest for biotechnological applications. Self-rolled tubes can be filled with cells during their folding providing the desired homogeneity of filling. Individual tubes of different diameters could be used to investigate cell behaviour in confinement in conditions of structural anisotropy as well as to mimic blood vessels. Due to their directionality tubes could be used to guide the growth of cells that is of interest for regeneration of neuronal tissue. Reversibly foldable films allow triggered capture and release of the cells that could be implemented for controlled cell delivery. In perspective, self-assembled 3D constructs with aligned pores could be used for bottom-up engineering of the scaffolds, mimicking such tissues as cortical bone and skeletal muscle, which are characterized by repeating longitudinal units. Such constructs can be also considered as a good alternative of traditional 2D flat cell culture.

This thesis is focused on the design and development of an approach, allowing the fabrication of biocompatible/biodegradable self-rolled polymer tubes, which are sensitive to stimuli at physiological conditions, can be homogenously filled with cells and are able to self-assemble into a complex 3D construct with uniaxially aligned pores. These constructs are aimed to recreate the microstructure of tissues with structural anisotropy, such as of muscles and bones. The approach consists of two steps of self-assembly. As a first step, cells are adsorbed on the top of an unfolded bilayer; triggered rolling results in a parallel encapsulation of cells inside the tubes. As a second step, the formed self-rolled tubes with encapsulated cells can be assembled in a uniaxial tubular scaffold. Three polymer systems were designed and investigated in the present work in order to allow triggered folding of the bilayer. These systems allow either reversible or irreversible tube formation. The possibility to encapsulate microobjects inside self-rolled polymer tubes was demonstrated on the example of silica particles, yeast cells and mammalian cells. At conditions when bilayer film is unfolded, particles or cells were deposited from their aqueous dispersion on the top of bilayer. An appropriate change of conditions triggers folding of the bilayer and results in encapsulation of particles or cells inside the tubes. One way swelling of an active polymer allows irreversible encapsulation of cells in a way that tubes do not unroll and cells cannot escape. It was demonstrated that encapsulated cells can proliferate and divide inside the tubes for a long period of time. Since used polymers are optically transparent, encapsulated cells can be easily observed using optical and fluorescent microscopy. Reversible swelling of an active polymer provides the possibility to release encapsulated objects. It was demonstrated that in aqueous media microtubes possessing small amount of negatively charged groups on external walls self-assemble in the presence of oppositely charged microparticles that results in a formation of 3D constructs. In obtained aggregates tubes and therefore pores were well-aligned and the orientation degree was extremely high. Moreover, the approach allows the design of porous materials with complex architectures formed by tubes of different sorts. The assembly of cell-laden microtubes results in a formation of uniaxial tubular scaffold homogeneously filled with cells. The results presented in this work demonstrate that the proposed approach is of practical interest for biotechnological applications. Self-rolled tubes can be filled with cells during their folding providing the desired homogeneity of filling. Individual tubes of different diameters could be used to investigate cell behaviour in confinement in conditions of structural anisotropy as well as to mimic blood vessels. Due to their directionality tubes could be used to guide the growth of cells that is of interest for regeneration of neuronal tissue. Reversibly foldable films allow triggered capture and release of the cells that could be implemented for controlled cell delivery. In perspective, self-assembled 3D constructs with aligned pores could be used for bottom-up engineering of the scaffolds, mimicking such tissues as cortical bone and skeletal muscle, which are characterized by repeating longitudinal units. Such constructs can be also considered as a good alternative of traditional 2D flat cell culture.