Jay Hoon Park

University of Massachusetts Lowell | UML · Department of Plastics Engineering

Stiff, strong and tough ultrafine polyethylene fibers that rival the best high performance fibers, but with diameters less than one micron, are fabricated for the first time by “gel-electrospinning.” In this process, solution concentration and process temperatures are chosen to induce the formation of gel filaments “in flight,” which are subsequent...

As Macromolecules celebrates its 50th anniversary, we reflect on the impact of polymer chemistry and engineering on the advancement of synthetic polymer fibers. In this Perspective, we focus on two exemplary cases: (i) high performance fibers and (ii) ultrafine electrospun fibers. High performance in this context refers to fibers like Kevlar and Sp...

We report silver (Ag)/ceramic nanofibers with highly robust and sensitive optical sensory capabilities that can withstand harsh conditions. These nanofibers are fabricated by first electrospinning solutions of poly vinyl alcohol (PVA) and metal precursor polymers, followed by subsequent series of heat treatment. The reported fabrication method demo...

Mesoscale simulation, electrospinning and Raman scattering experiments have been carried out to demonstrate that examination and control of nanorod configuration in a polymer matrix under elongational flow and confinement can lead to enhanced sensing. First, coarse-grained molecular dynamics (CGMD) was employed to probe the diffusivity, orientation...

Polyacrylonitrile (PAN) and ambient temperature-curable organopolysilazane were combined to successfully fabricate PAN/polymer-derived ceramic (PDC) hybrid nanofiber separator using a single-step electrospinning process. The amount of added precursor was varied from 10 to 30% to characterize the effects of various loadings on the mechanical, therma...

Leakage flows due to a poor fit can greatly reduce the mask protection efficiency. However, accurate quantification of leakages is lacking due to the absence of standardized tests and difficulties in quantifying mask gaps. The objective of this study is to quantify the leakage flows around surgical masks with gaps of varying areas and locations. An...

The strength and toughness of material extrusion 3D printed parts is increased through the extrusion of core-sheath dual material thermoplastic filament feedstocks in which the filament core has a significantly higher glass transition temperature (Tg) than the filament sheath. Parts printed with these dual material filaments can thus be annealed af...

This chapter introduces the use of thermoset polymers in additive manufacturing. The primary additive manufacturing categories in which thermosetting material systems are used. “Material Extrusion, Photopolymerization, and Material Jetting” are the focus of discussion. For each technique, common chemistries, specific processing routes, and the rela...

Smart textiles are adaptive materials that use established textile methods to integrate multifunctionalities beyond apparels. Despite recent advancement, a significant gap exists between commercial needs and the academic state of the art. In this perspective, we aim to address the gap by (i) holistically investigating smart textile system operation...

Polyamides (PAs) are repeatedly exposed to environments of varying humidity throughout their service life. Due to their hygroscopic nature, moisture diffusion can alter the polymer properties, sometimes irreversibly. It has been previously found that the effect of transport of water on the structure, morphology, and physical properties of polymers...

Many types of consumer-grade packaging can be used in material extrusion additive manufacturing processes, providing a high-value output for waste plastics. However, many of these plastics have reduced mechanical properties and increased warpage/shrinkage compared to those commonly used in three-dimensional (3D) printing. The addition of reinforcin...

We report a facile fabrication of porous silicon nanofibers by a simple three-stage procedure. Polymer/silicon precursor composite nanofibers are first fabricated by electrospinning, a water-based spinning dope, which undergoes subsequent heat treatment and then reduction using magnesium to be converted into porous silicon nanofibers. The porous si...

We have incorporated graphene nanoribbons (GNRs) which are unzipped from multi-wall carbon nanotubes (MWCNT) into silicon-carbon (Si/C) nanofibers, not only to reinforce hybrid Si/C fibers, but also to increase the electrical conductivity and charge transport capability of fibers. We demonstrated that GNRs are promising components for improving the...

We have incorporated graphene nanoribbons (GNRs) which are unzipped from multi-wall carbon nanotubes (MWCNT) into silicon-carbon (Si/C) nanofibers, not only to reinforce hybrid Si/C fibers, but also to increase the electrical conductivity and charge transport capability of fibers. We demonstrated that GNRs are promising components for improving the...

Submicron scale titanium carbide-carbon (TiC-C) hybrid nanofibers have been synthesized from electrospinning of titania (TiO2) nanoparticle and polyacrylonitrile (PAN) in dimethyl formaldehyde (DMF) solution, followed by carbothermal reduction of TiO2 with carbon at high temperature. Scanning Electron Microscope (SEM) images of TiC-C nanofibers sho...

The challenges for rechargeable lithium-oxygen batteries of low practical capacity and poor round-trip efficiency urgently demand effective cathode materials to overcome the limitations. However, the synergy between the multiple active materials was not well understood at large. Herein, we describe findings of the synergistic effect between electro...

We have investigated the effect of nanorods on the symmetry breaking of a model diblock copolymer under cylindrical confinement using coarse-grained molecular dynamics. Unlike nanoparticles, nanorods can readily be interconnected with each other and also induce connection across self-assembly domains at much lower loading than nanoparticles. Such i...

We have comprehensively studied the effect of nanoparticle selectivity on the self-assembly of symmetrical block copolymer (BCP) under cylindrical confinement using simulation and experiment. For the simulation, a coarse-grained molecular dynamics (CGMD) simulation has been utilized, and we investigated the confined assembly using nanoparticles wit...

Incorporation of nanorods (NRs) into a polymer matrix can greatly enhance the material properties, but the aggregation of NRs prevents the full realization of their potential. Using coarse-grained molecular dynamics simulation with the dissipative particle dynamics thermostat, we have systematically examined how key material and processing paramete...

Electrospinning is now a relatively common method for the production of one-dimensional nanomaterials from a scalable, cost-effective process. Recently, we have developed an approach to generate inorganic nanofibers with various nanostructures through a high-throughput, water-based solution process. We have utilized this process to generate nanofib...

Antifouling surfaces are critical for the good performance of functional materials in various applications including water filtration, medical implants, and biosensors. In this study, we synthesized amphiphilic triblock terpolymers (tri-BCPs, coded as KB) and fabricated amphiphilic nanofibers by electrospinning of solutions prepared by mixing the K...

Nanorods are often incorporated into a polymer to enhance its functionality. Gaining control over the placement of nanorods in polymer is important to improve the desired nanocomposite material property and for application like solar cell. First, we used coarse-grained molecular dynamics (CGMD) simulation to quantitatively examine the effect of elo...

Our recent experimental study on electrospinning of block copolymer (BCP)–nanoparticle (NP) nanocomposites has revealed the formation of unique self-assembling structures in submicron scale fibers. In this paper, we use coarse-grained molecular dynamics (MD) simulations to investigate the effect of cylindrical confinement on self-assembly of model...

Multiaxial (triaxial/coaxial) electrospinning is utilized to fabricate block copolymer (poly(styrene-b-isoprene), PS-b-PI) nanofibers covered with a silica shell. The thermally stable silica shell allows post-fabrication annealing of the fibers to obtain equilibrium self-assembly. For the case of coaxial nanofibers, block copolymers with different...