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Rebane I, Levin KJ, Mäeorg U, Johanson U, Piirimägi P, Tätte T, Tamm T. Enhanced Low-Density Silicone Foams Blown by Water-Hydroxyl Blends. Polymers (Basel) 2023; 15:4425. [PMID: 38006148 PMCID: PMC10675139 DOI: 10.3390/polym15224425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/04/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Water, alcohols, diols, and glycerol are low-cost blowing agents that can be used to create the desired silicone foam structures. Although their combined use can be beneficial, it remains unclear how it affects the physical properties of the resulting materials. We conducted a comparative study of these hydroxyl-bearing blowing agents in fumed silica- and mica-filled polymer composite systems for simultaneous blowing and crosslinking to obtain a low-density, uniform porosity and superior mechanical properties. The foams were optimized for a uniform open-pore structure with densities ranging from 75 to 150 kg‧m-3. Varying the diol chain length (Cn) from one to seven carbons can alter the foam density and structure, thereby enhancing the foam tensile strength while maintaining a low density. Replacing 10 mol% of water with 1,4-butanediol decreased the density by 26%, while increasing the specific strength by 5%. By combining glycerol and water blowing, the resulting foams exhibited a 30% lower apparent density than their water-blown analogs. The results further showed that Cn > 4 alkane chain diols had an odd-even effect on the apparent density and cell wall thickness. All foamable compositions had viscosities of approximately 7000 cSt and curing times below 2 min, allowing for quick dispensing and sufficient time for the foam to cure in semi-industrial volumes.
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Affiliation(s)
- Ingrid Rebane
- Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia; (K.J.L.); (U.J.)
| | - Karl Jakob Levin
- Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia; (K.J.L.); (U.J.)
| | - Uno Mäeorg
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia;
| | - Urmas Johanson
- Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia; (K.J.L.); (U.J.)
| | | | - Tauri Tätte
- Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia; (K.J.L.); (U.J.)
| | - Tarmo Tamm
- Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia; (K.J.L.); (U.J.)
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Kim JH, Schaible N, Hall JK, Bartolák-Suki E, Deng Y, Herrmann J, Sonnenberg A, Behrsing HP, Lutchen KR, Krishnan R, Suki B. Multiscale stiffness of human emphysematous precision cut lung slices. SCIENCE ADVANCES 2023; 9:eadf2535. [PMID: 37205750 PMCID: PMC10198632 DOI: 10.1126/sciadv.adf2535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 04/14/2023] [Indexed: 05/21/2023]
Abstract
Emphysema is a debilitating disease that remodels the lung leading to reduced tissue stiffness. Thus, understanding emphysema progression requires assessing lung stiffness at both the tissue and alveolar scales. Here, we introduce an approach to determine multiscale tissue stiffness and apply it to precision-cut lung slices (PCLS). First, we established a framework for measuring stiffness of thin, disk-like samples. We then designed a device to verify this concept and validated its measuring capabilities using known samples. Next, we compared healthy and emphysematous human PCLS and found that the latter was 50% softer. Through computational network modeling, we discovered that this reduced macroscopic tissue stiffness was due to both microscopic septal wall remodeling and structural deterioration. Lastly, through protein expression profiling, we identified a wide spectrum of enzymes that can drive septal wall remodeling, which, together with mechanical forces, lead to rupture and structural deterioration of the emphysematous lung parenchyma.
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Affiliation(s)
- Jae Hun Kim
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Mechanobiologix, LLC, Newton, MA, USA
| | - Niccole Schaible
- Mechanobiologix, LLC, Newton, MA, USA
- Center for Vascular Biology Research, Department of Emergency Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Joseph K. Hall
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | | | - Yuqing Deng
- Department of Mechanical Engineering, Boston University, Boston, MA, USA
| | - Jacob Herrmann
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- University of Iowa, Iowa City, IA, USA
| | - Adam Sonnenberg
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | | | - Kenneth R. Lutchen
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Ramaswamy Krishnan
- Mechanobiologix, LLC, Newton, MA, USA
- Center for Vascular Biology Research, Department of Emergency Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Mechanobiologix, LLC, Newton, MA, USA
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A Preliminary Experimental Study of Polydimethylsiloxane (PDMS)-To-PDMS Bonding Using Oxygen Plasma Treatment Incorporating Isopropyl Alcohol. Polymers (Basel) 2023; 15:polym15041006. [PMID: 36850290 PMCID: PMC9958961 DOI: 10.3390/polym15041006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 02/22/2023] Open
Abstract
Polydimethylsiloxane (PDMS) is a widely used material for soft lithography and microfabrication. PDMS exhibits some promising properties suitable for building microfluidic devices; however, bonding PDMS to PDMS and PDMS to other materials for multilayer structures in microfluidic devices is still challenging due to the hydrophobic nature of the surface of PDMS. This paper presents a simple yet effective method to increase the bonding strength for PDMS-to-PDMS using isopropyl alcohol (IPA). The experiment was carried out to evaluate the bonding strength for both the natural-cured and the heat-cured PDMS layer. The results show the effectiveness of our approach in terms of the improved irreversible bonding strength, up to 3.060 MPa, for the natural-cured PDMS and 1.373 MPa for the heat-cured PDMS, while the best bonding strength with the existing method in literature is 1.9 MPa. The work is preliminary because the underlying mechanism is only speculative and open for future research.
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Hsieh GW, Shih LC, Chen PY. Porous Polydimethylsiloxane Elastomer Hybrid with Zinc Oxide Nanowire for Wearable, Wide-Range, and Low Detection Limit Capacitive Pressure Sensor. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:256. [PMID: 35055273 PMCID: PMC8779111 DOI: 10.3390/nano12020256] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 02/01/2023]
Abstract
We propose a flexible capacitive pressure sensor that utilizes porous polydimethylsiloxane elastomer with zinc oxide nanowire as nanocomposite dielectric layer via a simple porogen-assisted process. With the incorporation of nanowires into the porous elastomer, our capacitive pressure sensor is not only highly responsive to subtle stimuli but vigorously so to gentle touch and verbal stimulation from 0 to 50 kPa. The fabricated zinc oxide nanowire-porous polydimethylsiloxane sensor exhibits superior sensitivity of 0.717 kPa-1, 0.360 kPa-1, and 0.200 kPa-1 at the pressure regimes of 0-50 Pa, 50-1000 Pa, and 1000-3000 Pa, respectively, presenting an approximate enhancement by 21-100 times when compared to that of a flat polydimethylsiloxane device. The nanocomposite dielectric layer also reveals an ultralow detection limit of 1.0 Pa, good stability, and durability after 4000 loading-unloading cycles, making it capable of perception of various human motions, such as finger bending, calligraphy writing, throat vibration, and airflow blowing. A proof-of-concept trial in hydrostatic water pressure sensing has been demonstrated with the proposed sensors, which can detect tiny changes in water pressure and may be helpful for underwater sensing research. This work brings out the efficacy of constructing wearable capacitive pressure sensors based on a porous dielectric hybrid with stress-sensitive nanostructures, providing wide prospective applications in wearable electronics, health monitoring, and smart artificial robotics/prosthetics.
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Affiliation(s)
- Gen-Wen Hsieh
- Institute of Lighting and Energy Photonics, College of Photonics, National Yang Ming Chiao Tung University, 301, Section 2, Gaofa 3rd Road, Guiren District, Tainan 71150, Taiwan
| | - Liang-Cheng Shih
- Institute of Photonic System, College of Photonics, National Yang Ming Chiao Tung University, 301, Gaofa 3rd Road, Section 2, Guiren District, Tainan 71150, Taiwan; (L.-C.S.); (P.-Y.C.)
| | - Pei-Yuan Chen
- Institute of Photonic System, College of Photonics, National Yang Ming Chiao Tung University, 301, Gaofa 3rd Road, Section 2, Guiren District, Tainan 71150, Taiwan; (L.-C.S.); (P.-Y.C.)
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