{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/139658"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/139658","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"All-atom and Coarse-grained Molecular Dynamics Modeling of Various Polymeric and Composite Materials","abstract":"This dissertation leverages molecular dynamics (MD) simulations to reveal the structure-property relationship of various polymeric and composite materials, including polyacrylonitrile-poly(methyl methacrylate) (PAN-b-PMMA) copolymers, polyetherimide (PEI)-graphene composites, and epoxy network polymers, by bridging molecular-level behaviors and macroscopic thermomechanical properties. First, all-atom MD simulations are used to improve the design of porous carbon fibers derived from PAN-b-PMMA copolymers for energy storage applications. A new method is developed to characterize the interfacial area between different domains. Simulation results reveal a molecular mechanism underlying the experimental findings, demonstrating that the interfacial area -- a key predictor of the electrochemical performance of the resulting fibers after oxidation and carbonization -- reaches a maximal value when the two blocks are at a 50% volume fraction. This understanding paves the way for designing PCFs with optimal energy storage capabilities. Next, all-atom MD simulations are used to explore a strategy to enhance polymer nanocomposites by mitigating nanofiller aggregation. Experiments show that coating the surface of reduced graphene oxide (rGO) nanoparticles with PEI chains can improve their dispersion in a PEI matrix and thus lead to stronger composites. Simulations reveal that the PEI chains grafted to the edge surface a rGO particle form a protective layer of the particle, preventing particle aggregation and creating a more compatible interface with the host polymer. This enhanced compatibility makes the composites perform more strongly under mechanical loading, as seen experimentally. Polymer grafting is therefore confirmed as a powerful strategy for creating stronger, more reliable composite materials. Finally, a computationally efficient coarse-grained (CG) model is developed for epoxy resins based on EPON 862 (Diglycidyl Ether of Bisphenol F) monomers and diethyltoluenediamine (DETDA) curing agent, a critical component of high-performance composite materials. The CG model is transferable across a wide range of temperatures and is used to predict the mechanical properties of epoxy resins with reasonable accuracy. It provides a facile approach to creating large epoxy networks. Then via a backmapping procedure, the CG network is mapped to an all-atom network with the same topology. The all-atom and CG networks are used for understanding the fracture behavior of epoxy resins at experimentally relevant spatiotemporal scales. Collectively, this dissertation provides a suite of validated computational tools and fundamental molecular insights to advance the bottom-up design and optimization of next-generation polymeric and composite materials.","abstract_html":"This dissertation leverages molecular dynamics (MD) simulations to reveal the structure-property relationship of various polymeric and composite materials, including polyacrylonitrile-poly(methyl methacrylate) (PAN-b-PMMA) copolymers, polyetherimide (PEI)-graphene composites, and epoxy network polymers, by bridging molecular-level behaviors and macroscopic thermomechanical properties. First, all-atom MD simulations are used to improve the design of porous carbon fibers derived from PAN-b-PMMA copolymers for energy storage applications. A new method is developed to characterize the interfacial area between different domains. Simulation results reveal a molecular mechanism underlying the experimental findings, demonstrating that the interfacial area -- a key predictor of the electrochemical performance of the resulting fibers after oxidation and carbonization -- reaches a maximal value when the two blocks are at a 50% volume fraction. This understanding paves the way for designing PCFs with optimal energy storage capabilities. Next, all-atom MD simulations are used to explore a strategy to enhance polymer nanocomposites by mitigating nanofiller aggregation. Experiments show that coating the surface of reduced graphene oxide (rGO) nanoparticles with PEI chains can improve their dispersion in a PEI matrix and thus lead to stronger composites. Simulations reveal that the PEI chains grafted to the edge surface a rGO particle form a protective layer of the particle, preventing particle aggregation and creating a more compatible interface with the host polymer. This enhanced compatibility makes the composites perform more strongly under mechanical loading, as seen experimentally. Polymer grafting is therefore confirmed as a powerful strategy for creating stronger, more reliable composite materials. Finally, a computationally efficient coarse-grained (CG) model is developed for epoxy resins based on EPON 862 (Diglycidyl Ether of Bisphenol F) monomers and diethyltoluenediamine (DETDA) curing agent, a critical component of high-performance composite materials. The CG model is transferable across a wide range of temperatures and is used to predict the mechanical properties of epoxy resins with reasonable accuracy. It provides a facile approach to creating large epoxy networks. Then via a backmapping procedure, the CG network is mapped to an all-atom network with the same topology. The all-atom and CG networks are used for understanding the fracture behavior of epoxy resins at experimentally relevant spatiotemporal scales. Collectively, this dissertation provides a suite of validated computational tools and fundamental molecular insights to advance the bottom-up design and optimization of next-generation polymeric and composite materials.","abstract_has_math":false,"creators":["Hao, Xi"],"institution":"Virginia Tech","degree_name":"Doctor of Philosophy","degree_level":"doctoral","degree_discipline":"Macromolecular Science and Engineering","degree_department":"Graduate School","school":null,"contributors":[],"advisors":[],"committee_chairs":["Cheng, Shengfeng"],"committee_members":["Seidel, Gary D.","Deshmukh, Sanket A.","Bortner, Michael J.","Liu, Guoliang"],"year":2025,"date_issued":"2025-11-14","date_published":"2025-11-14","updated_at":"2026-07-22T22:19:22Z","subjects":["Molecular Dynamics Simulation","Coarse-Graining","Block Copolymers","Epoxy Resins","Composite Materials"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:44791"],"render_values":[{"text":"vt_gsexam:44791","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/139658","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Cheng, Shengfeng"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Seidel, Gary D.","Deshmukh, Sanket A.","Bortner, Michael J.","Liu, Guoliang"]},{"key":"dc:contributor.department","label":"Department","values":["Graduate School"]},{"key":"dc:creator","label":"Author","values":["Hao, Xi"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-11-15T09:00:31Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-11-15T09:00:31Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-11-14"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Macromolecular Science and Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Molecular Dynamics Simulation","Coarse-Graining","Block Copolymers","Epoxy Resins","Composite Materials"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:44791"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/139658"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This dissertation leverages molecular dynamics (MD) simulations to reveal the structure-property relationship of various polymeric and composite materials, including polyacrylonitrile-poly(methyl methacrylate) (PAN-b-PMMA) copolymers, polyetherimide (PEI)-graphene composites, and epoxy network polymers, by bridging molecular-level behaviors and macroscopic thermomechanical properties. First, all-atom MD simulations are used to improve the design of porous carbon fibers derived from PAN-b-PMMA copolymers for energy storage applications. A new method is developed to characterize the interfacial area between different domains. Simulation results reveal a molecular mechanism underlying the experimental findings, demonstrating that the interfacial area -- a key predictor of the electrochemical performance of the resulting fibers after oxidation and carbonization -- reaches a maximal value when the two blocks are at a 50% volume fraction. This understanding paves the way for designing PCFs with optimal energy storage capabilities. Next, all-atom MD simulations are used to explore a strategy to enhance polymer nanocomposites by mitigating nanofiller aggregation. Experiments show that coating the surface of reduced graphene oxide (rGO) nanoparticles with PEI chains can improve their dispersion in a PEI matrix and thus lead to stronger composites. Simulations reveal that the PEI chains grafted to the edge surface a rGO particle form a protective layer of the particle, preventing particle aggregation and creating a more compatible interface with the host polymer. This enhanced compatibility makes the composites perform more strongly under mechanical loading, as seen experimentally. Polymer grafting is therefore confirmed as a powerful strategy for creating stronger, more reliable composite materials. Finally, a computationally efficient coarse-grained (CG) model is developed for epoxy resins based on EPON 862 (Diglycidyl Ether of Bisphenol F) monomers and diethyltoluenediamine (DETDA) curing agent, a critical component of high-performance composite materials. The CG model is transferable across a wide range of temperatures and is used to predict the mechanical properties of epoxy resins with reasonable accuracy. It provides a facile approach to creating large epoxy networks. Then via a backmapping procedure, the CG network is mapped to an all-atom network with the same topology. The all-atom and CG networks are used for understanding the fracture behavior of epoxy resins at experimentally relevant spatiotemporal scales. Collectively, this dissertation provides a suite of validated computational tools and fundamental molecular insights to advance the bottom-up design and optimization of next-generation polymeric and composite materials."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["A grand mission in materials science is to design new, high-performance materials from the ground up, atom by atom, to solve some of today's biggest technological challenges. In this dissertation, powerful computer simulations, much like a virtual microscope, are used to understand and predict how materials behave at the molecular level. First, computer models are used to figure out the best recipe for making a special type of carbon fiber that can store more energy. My simulations show that a 50/50 mix of two specific plastics creates the ideal structure that leads to carbon fibers with the best performance, consistent with experimental evidence. Simulations further provide a molecular picture of why this mixing ratio is the optimum, as it maximizes the interfacial area between different plastic domains. In the second project, molecular simulations are used to understand how nanoparticles can be more uniformly distributed in a polymer host, which is often needed for the mixture (called a composite) to perform strongly under mechanical loading. Experiments indicate that coating nanoparticles with polymer chains can help achieve this goal. As shown in my simulations, this is because the polymer chains tethered to the nanoparticle surface form a protective layer, which reduces the tendency of nanoparticles to agglomerate. Furthermore, this protective layer makes the nanoparticles bind more strongly with the polymer host. These two effects combined lead to stronger composites. Finally, a new computational model is developed for epoxy resins, which have a network structure formed by crosslinking long molecular chains. With this model, large networks can be efficiently constructed and used for predicting the mechanical response including fracture behavior of epoxy materials. Overall, my work provides a set of powerful computer-based tools to help achieve a deeper understanding of how materials work at molecular scales. The insights revealed with these tools will help accelerate the discovery and creation of next generation advanced materials."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Doctor of Philosophy"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["All-atom and Coarse-grained Molecular Dynamics Modeling of Various Polymeric and Composite Materials"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Cheng, Shengfeng"],"dc:contributor.committeemember":["Seidel, Gary D.","Deshmukh, Sanket A.","Bortner, Michael J.","Liu, Guoliang"],"dc:contributor.department":["Graduate School"],"dc:creator":["Hao, Xi"],"dc:date.accessioned":["2025-11-15T09:00:31Z"],"dc:date.available":["2025-11-15T09:00:31Z"],"dc:date.issued":["2025-11-14"],"dc:description.abstract":["This dissertation leverages molecular dynamics (MD) simulations to reveal the structure-property relationship of various polymeric and composite materials, including polyacrylonitrile-poly(methyl methacrylate) (PAN-b-PMMA) copolymers, polyetherimide (PEI)-graphene composites, and epoxy network polymers, by bridging molecular-level behaviors and macroscopic thermomechanical properties. First, all-atom MD simulations are used to improve the design of porous carbon fibers derived from PAN-b-PMMA copolymers for energy storage applications. A new method is developed to characterize the interfacial area between different domains. Simulation results reveal a molecular mechanism underlying the experimental findings, demonstrating that the interfacial area -- a key predictor of the electrochemical performance of the resulting fibers after oxidation and carbonization -- reaches a maximal value when the two blocks are at a 50% volume fraction. This understanding paves the way for designing PCFs with optimal energy storage capabilities. Next, all-atom MD simulations are used to explore a strategy to enhance polymer nanocomposites by mitigating nanofiller aggregation. Experiments show that coating the surface of reduced graphene oxide (rGO) nanoparticles with PEI chains can improve their dispersion in a PEI matrix and thus lead to stronger composites. Simulations reveal that the PEI chains grafted to the edge surface a rGO particle form a protective layer of the particle, preventing particle aggregation and creating a more compatible interface with the host polymer. This enhanced compatibility makes the composites perform more strongly under mechanical loading, as seen experimentally. Polymer grafting is therefore confirmed as a powerful strategy for creating stronger, more reliable composite materials. Finally, a computationally efficient coarse-grained (CG) model is developed for epoxy resins based on EPON 862 (Diglycidyl Ether of Bisphenol F) monomers and diethyltoluenediamine (DETDA) curing agent, a critical component of high-performance composite materials. The CG model is transferable across a wide range of temperatures and is used to predict the mechanical properties of epoxy resins with reasonable accuracy. It provides a facile approach to creating large epoxy networks. Then via a backmapping procedure, the CG network is mapped to an all-atom network with the same topology. The all-atom and CG networks are used for understanding the fracture behavior of epoxy resins at experimentally relevant spatiotemporal scales. Collectively, this dissertation provides a suite of validated computational tools and fundamental molecular insights to advance the bottom-up design and optimization of next-generation polymeric and composite materials."],"dc:description.abstractgeneral":["A grand mission in materials science is to design new, high-performance materials from the ground up, atom by atom, to solve some of today's biggest technological challenges. In this dissertation, powerful computer simulations, much like a virtual microscope, are used to understand and predict how materials behave at the molecular level. First, computer models are used to figure out the best recipe for making a special type of carbon fiber that can store more energy. My simulations show that a 50/50 mix of two specific plastics creates the ideal structure that leads to carbon fibers with the best performance, consistent with experimental evidence. Simulations further provide a molecular picture of why this mixing ratio is the optimum, as it maximizes the interfacial area between different plastic domains. In the second project, molecular simulations are used to understand how nanoparticles can be more uniformly distributed in a polymer host, which is often needed for the mixture (called a composite) to perform strongly under mechanical loading. Experiments indicate that coating nanoparticles with polymer chains can help achieve this goal. As shown in my simulations, this is because the polymer chains tethered to the nanoparticle surface form a protective layer, which reduces the tendency of nanoparticles to agglomerate. Furthermore, this protective layer makes the nanoparticles bind more strongly with the polymer host. These two effects combined lead to stronger composites. Finally, a new computational model is developed for epoxy resins, which have a network structure formed by crosslinking long molecular chains. With this model, large networks can be efficiently constructed and used for predicting the mechanical response including fracture behavior of epoxy materials. Overall, my work provides a set of powerful computer-based tools to help achieve a deeper understanding of how materials work at molecular scales. The insights revealed with these tools will help accelerate the discovery and creation of next generation advanced materials."],"dc:description.degree":["Doctor of Philosophy"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:44791"],"dc:identifier.uri":["https://hdl.handle.net/10919/139658"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Molecular Dynamics Simulation","Coarse-Graining","Block Copolymers","Epoxy Resins","Composite Materials"],"dc:title":["All-atom and Coarse-grained Molecular Dynamics Modeling of Various Polymeric and Composite Materials"],"dc:type":["Dissertation"],"thesis:degree_discipline":["Macromolecular Science and Engineering"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Doctor of Philosophy"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:22Z"}