In this study, one of the thermoresponsive polymers, block copolymer consisting of poly(ethylene glycol) and poly(N-isopropylacylamide), was investigated using Fourier transform infrared (FT-IR) spectroscopy, principal component analysis (PCA), and two-dimensional correlation spectroscopy (2D-COS). The apparent trend of the spectral changes in the temperature-dependent FT-IR spectra of poly(ethylene glycol)-block-poly(N-isopropylacylamide) (PEG-b-PNiPAAm) hydrogel during the heating process looks similar to that during the cooling process. The results of the PCA and 2D-COS, however, clearly indicate an irreversible phase transition mechanism of PEG-b-PNiPAAm hydrogel during the heating and cooling processes. It has been also shown that PEG affects the phase transition mechanism of PEG-b-PNiPAAm hydrogel, especially during the heating process. Consequently, we can successfully determine the phase transition temperature and the mechanism of PEG-b-PNiPAAm hydrogel during the heating and cooling processes using PCA and 2D-COS, respectively.
SharmaA.K.PrasherP.AljabaliA.A., et al.“Emerging Era of ‘Somes’: Polymersomes as Versatile Drug Delivery Carrier for Cancer Diagnostics and Therapy”. Drug Deliv. Transl. Res. 2020. 10(5): 1171–1190. doi:10.1007/s13346-020-00789-2.
2.
HeW.MaY.GaoX., et al.“Application of Poly(N-isopropylacrylamide) as Thermosensitive Smart Materials”. J. Phys. Conf. Ser. 2020, 1676: 012063doi:10.1088/1742-6596/1676/1/012063.
3.
XuX.LiuY.FuW., et al.“Poly(N-isopropylacrylamide)-Based Thermoresponsive Composite Hydrogels for Biomedical Applications”. Polymers. 2020, 12(3): 580doi:10.3390/polym12030580.
4.
FrazarE.M.ShahR.A.DziublaT.D., et al.“Multifunctional Temperature-Responsive Polymers as Advanced Biomaterials and Beyond”. J. Appl. Polym. Sci. 2020, 137(25): 48770doi:10.1002/app.48770.
5.
DoberenzF.ZengK.WillemsC., et al.“Thermoresponsive Polymers and Their Biomedical Application in Tissue Engineering: A Review”. J. Mater. Chem. B. 2020, 8(4): 607–628. doi:10.1039/C9TB02052G.
6.
AgnihotriP.RajR.KumarD., et al.“Short Oligo(ethylene glycol) Chain Incorporated Thermoresponsive Microgels: From Structural Analysis to Modulation of Solution Properties”. Soft Matter. 2020, 16(33): 7845–7859. doi:10.1039/D0SM01187H.
7.
HaddowP.McAuleyW.J.KirtonS.B., et al.“Poly(N-isopropyl acrylamide)–poly(ethylene glycol)–poly(N-isopropyl acrylamide) as a Thermoreversible Gelator for Topical Administration”. Mater. Adv. 2020, 1(3): 371–386. doi:10.1039/D0MA00080A.
8.
KawaguchiH.“On Going to a New Era of Microgel Exhibiting Volume Phase Transition”. Gels. 2020, 6(3): 26.
9.
Es SayedJ.LorthioirC.PerrinP., et al.“PEGylated NiPAM Microgels: Synthesis, Characterization and Colloidal Stability”. Soft Matter. 2019, 15(5): 963–972. doi:10.1039/C8SM02156B.
10.
GiaouziD.PispasS.“Synthesis and Self-Assembly of Thermoresponsive Poly(N-isopropylacrylamide)-b-poly(oligo ethylene glycol methyl ether acrylate) Double Hydrophilic Block Copolymers”. J. Polym. Sci., Part A: Polym. Chem. 2019, 57(13): 1467–1477. doi:10.1002/pola.29411.
11.
SponchioniM.Capasso PalmieroU.MoscatelliD.“Thermo-Responsive Polymers: Applications of Smart Materials in Drug Delivery and Tissue Engineering”. Mater. Sci. Eng., C. 2019, 102: 589–605. doi:10.1016/j.msec.2019.04.069.
12.
M. Mahmoudi, S. Agbolaghi, Z. Mozaffari, et al. ”Star-Like Poly(N-isopropylacrylamide) and Poly(ethylene glycol) Copolymers Self-Arranged in Newfound Single Crystals and Associated Novel Class of Polymer Brush Regimes with V-Type Tethers”. Macromol. Chem. Phys. 2018. 219(10): 1700638. doi:10.1002/macp.201700638.
13.
AlexanderA.AjazuddinJ.Khan, et al.“Polyethylene Glycol (PEG)-Poly(N-isopropylacrylamide) (PNIPAAm) Based Thermosensitive Injectable Hydrogels for Biomedical Applications”. Eur. J. Pharm. Biopharm. 2014, 88(3): 575–585. doi:10.1016/j.ejpb.2014.07.005.
14.
ChengV.LeeB.H.PaukenC., et al.“Poly(N-isopropylacrylamide-co-poly(ethylene glycol))-acrylate Simultaneously Physically and Chemically Gelling Polymer Systems”. J. Appl. Polym. Sci. 2007, 106(2): 1201–1207. doi:10.1002/app.26760.
15.
QinS.GengY.DischerD.E., et al.“Temperature-Controlled Assembly and Release from Polymer Vesicles of Poly(ethylene oxide)-block-poly(N-isopropylacrylamide)”. Adv. Mater. 2006, 18(21): 2905–2909. doi:10.1002/adma.200601019.
16.
ZhangW.ShiL.WuK., et al.“Thermoresponsive Micellization of Poly(ethylene glycol)-b-poly(N-isopropylacrylamide) in Water”. Macromolecules. 2005, 38(13): 5743–5747. doi:10.1021/ma0509199.
UlbrichtJ.JordanR.LuxenhoferR.“On the Biodegradability of Polyethylene Glycol, Polypeptoids and Poly(2-oxazoline)s”. Biomaterials. 2014, 35(17): 4848–4861. doi:10.1016/j.biomaterials.2014.02.029.
19.
AlexanderA.AjazuddinJ.Khan, et al.“Polyethylene Glycol (PEG)–Poly(N-isopropylacrylamide) (PNIPAAm) Based Thermosensitive Injectable Hydrogels for Biomedical Applications”. Eur. J. Pharm. Biopharm. 2014, 88(3): 575–585. doi:10.1016/j.ejpb.2014.07.005.
20.
I. Noda, Y. Ozaki. Two-Dimensional Correlation Spectroscopy: Applications in Vibrational and Optical Spectroscopy. Chichester, UK: John Wiley and Sons, Ltd., 2004.
21.
HeA.-Q.LiQ.YuZ.-Q., et al.“Investigation on the Luminescence Behavior of Terbium Acetylsalicylate/Bilirubin System via 2D-COS Approaches”. Spectrochim. Acta, Part A. 2021, 251: 119427doi:10.1016/j.saa.2021.119427.
22.
ParkY.HwangM.KimM., et al.“Characterization of the Phase Transition Mechanism of P(NiPAAm-co-AAc) Copolymer Hydrogel Using 2D Correlation IR Spectroscopy”. Spectrochim. Acta, Part A. 2021, 252: 119525doi:10.1016/j.saa.2021.119525.
23.
NishikawaY.ItouH.NodaI., et al.“Analysis of Nonlinear Structural Dynamics of Uncrystalized Polyester under Heating Using a Pulse-Induced Dynamic Compression (PDC) IR Method”. Vib. Spectrosc. 2020, 109: 103067doi:10.1016/j.vibspec.2020.103067.
24.
ParkY.JinS.ParkY., et al.“Studies on Chemical IR Images of Poly(hydroxybutyrate–co–hydroxyhexanoate)/Poly(ethylene glycol) Blends and Two-Dimensional Correlation Spectroscopy”. Polymers. 2019, 11(3): 507.
25.
ChaeB.SeoJ.H.MoonK.H., et al.“Thermal Induced Structural Changes of Polyhydroxyamide by Two-Dimensional (2D) Infrared Correlation Study”. J. Mol. Struct. 2018, 1167: 169–173. doi:10.1016/j.molstruc.2018.04.070.
26.
ParkY.HashimotoC.OzakiY., et al.“Understanding the Phase Transition of Linear Poly(N-isopropylacrylamide) Gel Under the Heating and Cooling Processes”. J. Mol. Struct. 2016, 1124: 144–150. doi:10.1016/j.molstruc.2016.02.067.
TomerN.MondalS.WanderaD., et al.“Modification of Nanofiltration Membranes by Surface-Initiated Atom Transfer Radical Polymerization for Produced Water Filtration”. Sep. Sci. Technol. 2009, 44(14): 3346–3368. doi:10.1080/01496390903212540.
29.
SunS.HuJ.TangH., et al.“Chain Collapse and Revival Thermodynamics of Poly(N-isopropylacrylamide) Hydrogel”. J. Phys. Chem. B. 2010, 114(30): 9761–9770. doi:10.1021/jp103818c.
30.
SchmidtP.DybalJ.TrchováM.“Investigations of the Hydrophobic and Hydrophilic Interactions in Polymer–Water Systems by ATR FT-IR and Raman Spectroscopy”. Vib. Spectrosc. 2006, 42(2): 278–283. doi:10.1016/j.vibspec.2006.05.005.
