Extending Alkenes’ Value Chain to Functionalized Polyolefins

Naphtha is one of the crude oil distillation products, bringing almost the lowest value-addition to crude oil, compared to other refinery products such as liquid petroleum gas, gasoline, and diesel. However, Naphtha can be converted to one of the highest value products at the end of the value chain, i.e., polyolefins. Although the production of conventional commodity polyolefins from crude oil, is considered as one of the final products in alkenes’ value chain, there are specialty polyolefins with higher values. Specialty polyolefins are small volume, high-performance thermoplastics with high-profit margins compared to traditional commodity polyolefins. Recently, some special purpose functionalized polyolefins have been developed as efficient substituents for high-performance engineering thermoplastics. Polyolefins are exploited as cost-effective platforms to produce these functionalized thermoplastics. They are promising candidates for replacing high-performance polymers with high-cost raw materials and elaborate production processes. So, functional polyolefins have introduced a new paradigm in the production of high-performance thermoplastics, extending the alkenes’ value chain and increasing profitability. High-performance specialty polyolefins may find exceptional markets in niche applications. In this chapter, the commercial specialty and functional polyolefins’ current situation and prospects are reviewed

Novel Configurations of Ionic Polymer-Metal Composites (IPMCs) As Sensors, Actuators, and Energy Harvesters

This dissertation starts with describing the IPMC and defining its chemical structure and fundamental characteristics in Chapter 1. The application of these materials in the form of actuator, sensor, and energy harvester are reported through a literature review in Chapter 2. The literature review involves some electromechanical modeling approaches toward physics of the IPMC as well as some of the experimental results and test reports. This chapter also includes a short description of the manufacturing process of the IPMC. Chapter 3 presents the mechanical modeling of IPMC in actuation. For modeling, shear deformation expected not to be significant. Hence, the Euler-Bernoulli beam theory considered to be the approach defining the shape and critical points of the proposed IPMC elements. Description of modeling of IPMC in sensing mode is in Chapter 4. Since the material undergoes large deformation, large beam deformation is considered for both actuation and sensing model. Basic configurations of IPMC as sensor and actuator are introduced in Chapter 5. These basic configurations, based on a systematic approach, generate a large number of possible configurations. Based on the presented mechanisms, some parameters can be defined, but the selection of a proper arrangement remained as an unknown parameter. This mater is addressed by introducing a decision-making algorithm. A series of design for slit cylindrical/tubular/helical IPMC actuators and sensors are introduced in chapter 5. A consideration related to twisting of IPMCs in helical formations is reported through some experiments. Combinations of these IPMC actuators and sensors can be made to make biomimetic robotic devices as some of them are discussed in this chapter and the following Chapters 6 and 7. Another set of IPMC actuator/sensor configurations are introduced as a loop sensor and actuator that are presented subsequently in Chapter 6. These configurations may serve as haptic and tactile feedback sensors, particularly for robotic surgery. Both of these configurations (loop and slit cylindrical) of IPMCs are discussed in details, and some experimental measurements and results are also carried out and reported. The model for different inputs is studied, and report of the feedback is presented. Various designs of these configurations of IPMC are also presented in chapter 7, including their extension to mechanical metamaterials and soft robots

Functional Nanomaterials and Polymer Nanocomposites: Current Uses and Potential Applications

This book covers a broad range of subjects, from smart nanoparticles and polymer nanocomposite synthesis and the study of their fundamental properties to the fabrication and characterization of devices and emerging technologies with smart nanoparticles and polymer integration

Synthesis and Characterizations of Lightweight, Highly Flexible Porous Polydimethylsiloxane (PDMS) Structures with Piezoresistive Strain Sensing Capabilities Using Solvent Evaporation Technique

Considering their specific structure, porous polymers have high adsorptive capacity, high flexibility, and high surface area compared to solid material. Highly flexible, deformable, and ultralightweight structures are required for advanced sensing applications such as wearable electronics and robotics. Hence, porous conductive polymer nanocomposites (CPNCs) have attracted significant attention for developing flexible piezoresistive sensors. In the first part of this dissertation, the application of solvent evaporation-induced phase separation (EIPS) as a promising technique to create porous polymer structures is investigated. The ternary polymer solution consisting of polymer/solvent/nonsolvent is explored. The ternary phase diagram is constructed, showing the thermodynamic equilibrium state for polymeric solutions consisting of Polydimethylsiloxane (PDMS)/Water/Tetrahydrofuran (THF). The possible composition path during the heat treatment and phase separation procedure is obtained. Moreover, the fabrication and characterization of porous PDMS structures developed by the EIPS technique are explored. The porous PDMS structures are formed by phase separation induced by removing the solvent, leading to water enriched droplets formation and removal during the stepping heat treatment procedure. The results show that the isolated pores with the adjustable pore size ranging from 330 µm to 1900 µm are obtained by tuning the water to the THF ratio. A wide range of elastic modulus ranging between 0.49-1.05 MPa was achieved without affecting the density of the porous sample by adjusting the solvent and non-solvent content in the solution. The second part of the dissertation proposes a two-step phase separation synthesis protocol based on a ternary polymer solution. THF and Toluene with various mixing ratios are utilized as the solvent phase. Two distinct pore size distributions were observed in the cast PDMS sheets. The large pores with an average of 509 µm are formed during the first step of the phase separation after THF is evaporated. The second phase separation occurs later at higher temperatures by the evaporation of Toluene, resulting in much smaller pores with an average size of 28 µm. The experiments reveal that raising the THF/solvent ratio increases the large pore concentration, and the small pore density is reduced. The elastic modulus is varied between 0.64-0.95 MPa, indicating that the proposed method can create porous structures with a wide range of flexibility while keeping the density constant. In the third part of the dissertation, a novel approach to synthesizing highly flexible and ultralightweight piezoresistive sensors is developed by combining the direct ink writing (DIW) and EIPS method. CPNC is prepared by dispersing carbon nanotubes (CNTs) at various concentrations in PDMS polymer, followed by mixing with solvent and nonsolvent phases to achieve a homogenous solution. Macroscale pores are established by designing structural printing patterns with adjustable infill densities, while the microscale pores are developed by EIPS of the deposited CPNC solution ink. Silica nanoparticles are utilized to modify the rheological properties of the DIW, evaluated by rheology experiments. A tunable porosity of up to 84% is achieved by controlling macroscale (infill density) and microscale porosity (polymer weight). The effect of macroscale/microscale porosity and printing nozzle sizes on the mechanical and piezoresistive behavior of the CPNC structures is explored. The electrical and mechanical testing demonstrate a durable, extremely deformable, and sensitive piezoresistive response without sacrificing mechanical performance. The flexibility and sensitivity of the CPNC structure are enhanced up to 900% and 67% with the development of dual-scale porosity. The application of the developed porous piezoresistive sensor for detecting human motion is also evaluated

Progenitor cells in auricular cartilage demonstrate promising cartilage regenerative potential in 3D hydrogel culture

The reconstruction of auricular deformities is a very challenging surgical procedure that could benefit from a tissue engineering approach. Nevertheless, a major obstacle is presented by the acquisition of sufficient amounts of autologous cells to create a cartilage construct the size of the human ear. Extensively expanded chondrocytes are unable to retain their phenotype, while bone marrow-derived mesenchymal stromal cells (MSC) show endochondral terminal differentiation by formation of a calcified matrix. The identification of tissue-specific progenitor cells in auricular cartilage, which can be expanded to high numbers without loss of cartilage phenotype, has great prospects for cartilage regeneration of larger constructs. This study investigates the largely unexplored potential of auricular progenitor cells for cartilage tissue engineering in 3D hydrogels