Preparation and Properties of Thermoresponsive P(N-Isopropylacrylamide-co-butylacrylate) Hydrogel Materials for Smart Windows

Abstract

Thermoresponsive polymers that exhibit phase transition in response to temperature change can be used as material for smart windows because they can control solar light transmission depending on the outside temperature. The development of thermoresponsive polymers for a smart window that can be used over a wide temperature range is required. Therefore, to obtain smart window materials that can be used at various temperatures, three-dimensional thermoresponsive P(NIPAm-co-BA) hydrogels were prepared by free radical polymerization from main monomer N-isopropylacrylamide, comonomer butyl acrylate, and crosslinking agent N,N′-methylenebisacrylamide (MBAm) in this study. This study examined the effect of BA content on the lower critical solution temperature (LCST) and the solar light transmittance of crosslinked P(NIPAm-co-BA) hydrogel films. The LCST of hydrogel films was found to be significantly decreased from 34.3 to 29.5°C with increasing BA content from 0 to 20 mol%. It was found that the transparent films at T=25°C (T<LCST) were converted to translucent films at a higher temperature (T=45°C) (T>LCST). These results suggested that the crosslinked P(NIPAm-co-BA) hydrogel materials prepared in this study could have high potential for application in smart window materials.

Engineered Ionene/PNIPAM Hybrid Dual-Response Material Generating Tunable and Unique Optical Modes for Adaptive Solar Transmittance Modulation

“…On the other hand, confirmation of the successful synthesis of PNIPAM via radical precipitation polymerization of the fully protonated monomer N -isopropylacrylamide (NIPAM) is shown by FTIR spectra (Figure S2, Supporting Information) such that double bond peaks showing in the range of 1600–1650 cm –1 and the peaks attributed to the stretching mode of vinyl double bonds in the range of 610–990 cm –1 had disappeared after polymerization. Further, the characteristic peaks of the as-synthesized PNIPAM are similar to those previously reported . These two organic polymers were physically blended in different weight ratios to produce a composite polymer exhibiting electrochromism and thermochromism.…”

“…Acetonitrile (CH 3 CN, 99.8%, Sigma-Aldrich), diethyl ether, bis (trifluoromethane)­sulfonimide lithium salt (LiTFSI, Alfa Aesar), and dimethyl formamide (DMF, Alfa Aesar) were used without any further purification. Viologen and poly­( N -isopropylacrylamide) were synthesized as described previously, whereas for ionene, , tetraethylene glycol was used instead of triethylene glycol for the azidation reaction.…”

Effect of the microstructure of n-butyl acrylate/N-isopropylacrylamide copolymers on their thermo-responsiveness, self-organization and gel properties in water

“…13,[17][18][19][20] For instance, P(BA-s-NIPAM ) statistical copolymers have been used to form hydrogels for which a decrease of T c from 34.3 to 29.5°C was observed when BA content increased up to 20 mol.%. 21 The specific structure of PBA-b-PNIPAM block copolymer enabled the formation of stable nanospheres both below and above T c 13,19 with a significant increase of diameter above T c . 13 Here, we aimed at further studying the properties of this family of copolymers at different temperatures and concentrations solution in relation with their composition and microstructure.…”

Preparation of the Temperature-Responsive Superhydrophobic Paper with High Stability

“…By comparing and analyzing different DSC curves, we can determine the phase transition low critical solution temperature (LCST) of temperatureresponsive polymers, which is the peak point of the heat flow change during heating. 37 It can be seen from the figure that the DSC curve of HFMA has no inflection point between 25 and 45 °C, so there is no glass transition temperature in this temperature range. The peak point of NIPAAm and PHFMA− PTSPM−PNIPAAm appeared near 33 and 32 °C, respectively, in the DSC curve and the DSC curves of the polymer are similar to those of monomer NIPAAm.…”

“…The differential scanning calorimetry (DSC) curves of different monomers and temperature-responsive polymers in the experiment are shown in Figure . By comparing and analyzing different DSC curves, we can determine the phase transition low critical solution temperature (LCST) of temperature-responsive polymers, which is the peak point of the heat flow change during heating . It can be seen from the figure that the DSC curve of HFMA has no inflection point between 25 and 45 °C, so there is no glass transition temperature in this temperature range.…”