Preparation and characterization of hydrophilic temperature‐dependent polyurethane containing the grafted poly(N‐isopropylacrylamide)

Abstract

The polyurethane (PU) structure is modified with dimethylolpropionic acid (DMPA) and poly(N‐isopropylacrylamide; poly[IPA]) to prepare hydrophilic temperature‐dependent PU that is investigated with reference to the degree of crosslinking, thermal properties of soft segment, tensile and shape memory performance, hydrophilic conversion of surface, and temperature‐dependent water swelling and water vapor permeability (WVP). The thermal properties of soft segment (melting, crystallization, and glass transition) are significantly affected by poly(IPA). Breaking tensile stress also increases with increasing IPA monomer content due to crosslinking effect but breaking tensile strain does not significantly decrease with increasing IPA monomer content. Shape recovery capability at 10°C steeply inclines to over 90% from 46.9% for unmodified PU by the grafting of poly(IPA), whereas shape retention at −25°C does not decrease below 90% with the increase in IPA content. Poly(IPA)‐grafted PU can display temperature‐dependent control of water swelling and WVP due to transformation of the grafted poly(IPA) depending on the surrounding temperature. POLYM. ENG. SCI., 59:1719–1728 2019. © 2019 Society of Plastics Engineers

Shape memory polyimide composites with high storage modulus and high glass transition temperature

“…Sample was put in the solvent and immersed for 24 h. The sample after swelling was gently removed, the solvent on the surface of the sample was absorbed, and the mass m after swelling was weighed to obtain. The swelling degree Q was calculated using the mass method of formula 1 (Chung et al, 2019).…”

Development of novel reversible thermometer from N‐isopropylacrylamide and dicyanodihydrofuran hydrazone probe

“…Researchers are interested in fabricating novel materials that have reversible temperatureinducible color-changing properties with or without additional properties of responsiveness to other stimuli. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] Polymeric thermometers composed of different combinations of chromophore entities have been recently studied. Color change is a reflection of structural shape changes of the polymer geometry induced by the temperature in the aqueous media.…”

Flexible crosslinking of polyurethane using grafted poly(dimethylsiloxane) with Epichlorohydrin and Bisphenol A end groups and its impact on the mechanical properties and low-temperature flexibility

“…[15][16][17] To functionalize PU, we applied a very simple and secure grafting method using allophanate bonding, which was developed by other researchers to enhance the water compatibility and antimicrobial activity of PU. [18][19][20][21] This grafting method was applied to modify various properties of PU, such as antifungal activity, 22 temperature-dependent permeation control, 23 high flexibility at extremely low temperatures, 24 pH-sensitive color change, 25 hydrogel-like water absorbing capacity, 26 antibacterial activity, 27 and electrical conductivity. 28 Meanwhile, PDMS was included in the PU network due to its resiliency and low-temperature flexibility, and various functional PDMS-PUs were reported: (1) PDMS was used to introduce soft segments in PU due to its low surface tension, low glass transition temperature, and biocompatibility; 29 (2) a PDMS-PU network polymer was developed for coating applications using a hyperbranched polyester as a crosslinking agent to improve the mechanical properties; 30 and (3) a PDMS-PU network polymer was applied to a vascular graft due to the flexibility, oxidative stability, blood compatibility, and tensile strength of PU.…”