Polymer and Organic Materials Commons^™

Evaluation Of Biomass As Bio-Additive In 3d Printing, Shuyang Zhang

Doctoral Dissertations

The petrol-based polymer has been widely applied in current daily life. The end-of-life of polymeric products has drawn environmental concerns. One of the solutions to such issues is to use bio-renewable materials to replace or reduce the use of petrol-based materials. Lignocellulosic materials are one of the potential candidates. Along with the features of 3D printing and the unique properties of biomass, 3D-printed biomass-based materials could be promising in preparing sustainable alternatives.

In this dissertation, lignin and other biomass were applied to various 3D printing techniques for sustainable composites. Stereolithography (SLA) was first used, and the kraft softwood lignin was …

Brain Inspired Organic Electronic Devices And Systems For Adaptive Signal Processing, Memory, And Learning., Subhadeep Koner

Doctoral Dissertations

A new class of electronic device has emerged which bear the potential for low powered brain like adaptive signal processing, memory, and learning. It is a non-linear resistor with memory coined as memristor. A memristor is a two-terminal electrical device which simultaneously changes its resistance (processing information) and store the resistance state pertaining to the applied power (memory). Therefore, it can collocate memory and processing much like our brain synapse which can save time and energy for information processing. Leveraging stored memory, it can thereby help future engineered systems to learn autonomously from past experiences. There has been a growing …

Chemistry And Functionality Of Plant Waxes: Applications Toward Postharvest Coatings, Francisco Miguel Angel Leyva Gutierrez

Doctoral Dissertations

The cuticle of all higher-plants is covered in lipidic layers of amorphous and crystalline waxes. The chemical composition and structure of cuticular waxes impart numerous functional properties to the surfaces of plants. Moreover, plant waxes are valuable industrial products with myriad applications; the postharvest coating of agricultural commodities for preservation serves as a salient example. There is an unfulfilled need in the agricultural sector for alternative wax materials to reduce reliance on imported waxes of botanical origin. Plant waxes are inherently complex mixtures composed of n-alkanes, as well as aliphatic alcohols, aldehydes, fatty acids, ketones, esters, and derivatives thereof. …

End-Capping Star-Like Polycaprolactone With Different Functional Groups And The Interaction With Smooth Muscle Cells, Qingya Zeng

Masters Theses

Polycaprolactone (PCL) is a PDA-approved biodegradable polymer with excellent biocompatibility and flexibility. My work has been designed to find out how different functional end groups in star-like PCL samples affect the surface properties (such as hydrophilicity, morphology) and bulk properties (such as thermal, mechanical, rheological properties, and crystallization), and consequently the behavior and functions of primary rat aortic smooth muscle cells (SMCs).

I focused on the synthesis of PCL with different functional groups and their characterizations. In chapter 2, PCL samples with four or six hydroxyl end groups were synthesized with different molecular weights ranging from 8,000 to 30,000 g/mol …

Inter-Droplet Membranes For Mechanical Sensing Applications, Nima Tamaddoni Jahromi

Doctoral Dissertations

This dissertation combines self-assembly phenomena of amphiphilic molecules with soft materials to create and characterize mechanoelectrical transducers and sensors whose sensing elements are thin-film bioinspired membranes comprised of phospholipids or amphiphilic polymers. We show that the structures of these amphiphilic molecules tune the mechanical and electrical properties of these membranes. We show that these properties affect the mechanoelectrical sensing characteristic and range of operation of these membrane transducers. In the experiments, we construct and characterize a membrane-based hair cell embodiment that enables the membrane to be responsive to mechanical perturbations of the hair. The resulting oscillations of membranes formed between …

Synthesis And Characterizations Of Stimuli-Responsive Polymeric Materials For Biomedical Applications, Shuangcheng Tang

Doctoral Dissertations

Stimuli-responsive polymeric materials have been now widely researched toward the biomedical applications including therapeutic delivery, bio-sensor surface modification, and tissue-engineering, etc., considering their desirable biocompatibility, tunable properties, and sensitivity toward physiological stimuli. Beyond the monoresponsive materials, polymers with responsiveness simultaneously toward multiple stimuli are paid great attention to because the control of responsive behaviors could be achieved at a more accurately and delicately level in a complex local environment. However, many challenges still exist such as maintaining integrity of the structure, shaping the morphology at micro- and macro-scale, and regulating a controllable and predictable transition behavior.

The objectives of this …

The Advancement Of Bacterial Cellulose As A Bone And Vascular Scaffolds, Ryan Lee Hammonds

Doctoral Dissertations

Bacterial cellulose (BC) is a natural hydrogel made of nanofibers. This material has been used in commercial products, including wound dressings. BC can be modified and optimized for improved performance in multiple applications. This work will focus on producing and characterizing resorbable cellulose, a composite for bone applications, and a composite for a synthetic venous valve leaflet.

BC can be produced and modified to perform as a degradable tissue scaffold. This is achieved by an oxidation procedure after the initial production and purification of native BC. A material characterization of oxidized BC was performed to identify the changes in properties …

Methods For Characterizing Mechanical Properties Of Wood Cell Walls Via Nanoindentation, Yujie Meng

Masters Theses

Nanoindentation is a method of contacting a material whose mechanical properties are unknown with another material whose properties are known. Nanoindentation has the advantage of being able to probe a material’s microstructure while being sensitive enough to detect variations in mechanical properties. However, nanoindentation has some limitations as a testing technique due to the specific formation and structure of some biomaterials. The main objective of this research is to identify any factors that influence the nanoindentation measurement of wood cell walls (a typical biomaterial).

The function of the embedding media in describing the properties of wood cells is poorly understood. …