scholarly journals Adamantane Functionalized Poly(2-oxazoline)s with Broadly Tunable LCST-Behavior by Molecular Recognition

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 374
Author(s):  
Joachim F. R. Van Guyse ◽  
Debaditya Bera ◽  
Richard Hoogenboom
Keyword(s):  
Phase Transition ◽  
Molecular Recognition ◽  
High Specificity ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Side Chains ◽  
Stimuli Responsive ◽  
Thermal Transitions ◽  
Stimuli Responsive Polymers ◽  
Interactive Behavior

Smart or adaptive materials often utilize stimuli-responsive polymers, which undergo a phase transition in response to a given stimulus. So far, various stimuli have been used to enable the modulation of drug release profiles, cell-interactive behavior, and optical and mechanical properties. In this respect, molecular recognition is a powerful tool to fine-tune the stimuli-responsive behavior due to its high specificity. Within this contribution, a poly(2-oxazoline) copolymer bearing adamantane side chains was synthesized via triazabicyclodecene-catalyzed amidation of the ester side chains of a poly(2-ethyl-2-oxazoline-stat-2-methoxycarbonylpropyl-2-oxazoline) statistical copolymer. Subsequent complexation of the pendant adamantane groups with sub-stoichiometric amounts (0–1 equivalents) of hydroxypropyl β-cyclodextrin or β-cyclodextrin enabled accurate tuning of its lower critical solution temperature (LCST) over an exceptionally wide temperature range, spanning from 30 °C to 56 °C. Furthermore, the sharp thermal transitions display minimal hysteresis, suggesting a reversible phase transition of the complexed polymer chains (i.e., the β-cyclodextrin host collapses together with the polymers) and a minimal influence by the temperature on the supramolecular association. Analysis of the association constant of the polymer with hydroxypropyl β-cyclodextrin via 1H NMR spectroscopy suggests that the selection of the macrocyclic host and rational polymer design can have a profound influence on the observed thermal transitions.

scholarly journals Constrained thermoresponsive polymers – new insights into fundamentals and applications

2021 ◽  
Vol 17 ◽  
pp. 2123-2163
Author(s):  
Patricia Flemming ◽  
Alexander S Münch ◽  
Andreas Fery ◽  
Petra Uhlmann
Keyword(s):  
Phase Transition ◽  
Current Knowledge ◽  
Polymer Chains ◽  
Switching Behavior ◽  
Solution Temperature ◽  
Miscibility Gap ◽  
Underlying Structure ◽  
Thermoresponsive Polymers ◽  
Critical Solution Temperature ◽  
Stimuli Responsive Polymers

In the last decades, numerous stimuli-responsive polymers have been developed and investigated regarding their switching properties. In particular, thermoresponsive polymers, which form a miscibility gap with the ambient solvent with a lower or upper critical demixing point depending on the temperature, have been intensively studied in solution. For the application of such polymers in novel sensors, drug delivery systems or as multifunctional coatings, they typically have to be transferred into specific arrangements, such as micelles, polymer films or grafted nanoparticles. However, it turns out that the thermodynamic concept for the phase transition of free polymer chains fails, when thermoresponsive polymers are assembled into such sterically confined architectures. Whereas many published studies focus on synthetic aspects as well as individual applications of thermoresponsive polymers, the underlying structure–property relationships governing the thermoresponse of sterically constrained assemblies, are still poorly understood. Furthermore, the clear majority of publications deals with polymers that exhibit a lower critical solution temperature (LCST) behavior, with PNIPAAM as their main representative. In contrast, for polymer arrangements with an upper critical solution temperature (UCST), there is only limited knowledge about preparation, application and precise physical understanding of the phase transition. This review article provides an overview about the current knowledge of thermoresponsive polymers with limited mobility focusing on UCST behavior and the possibilities for influencing their thermoresponsive switching characteristics. It comprises star polymers, micelles as well as polymer chains grafted to flat substrates and particulate inorganic surfaces. The elaboration of the physicochemical interplay between the architecture of the polymer assembly and the resulting thermoresponsive switching behavior will be in the foreground of this consideration.

scholarly journals Thermo- and Photoresponsive Behaviors of Dual-Stimuli-Responsive Organogels Consisting of Homopolymers of Coumarin-Containing Methacrylate

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 329
Author(s):  
Seidai Okada ◽  
Eriko Sato
Keyword(s):  
Functional Group ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Critical Solution Temperature ◽  
Equilibrium Degree ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Dual Functional ◽  
Wide Range ◽  
Increasing Temperature

Coumarin-containing vinyl homopolymers, such as poly(7-methacryloyloxycoumarin) (P1a) and poly(7-(2′-methacryloyloxyethoxy)coumarin) (P1b), show a lower critical solution temperature (LCST) in chloroform, which can be controlled by the [2 + 2] photochemical cycloaddition of the coumarin moiety, and they are recognized as monofunctional dual-stimuli-responsive polymers. A single functional group of monofunctional dual-stimuli-responsive polymers responds to dual stimuli and can be introduced more uniformly and densely than those of dual-functional dual-stimuli-responsive polymers. In this study, considering a wide range of applications, organogels consisting of P1a and P1b, i.e., P1a-gel and P1b-gel, respectively, were synthesized, and their thermo- and photoresponsive behaviors in chloroform were investigated in detail. P1a-gel and P1b-gel in a swollen state (transparent) exhibited phase separation (turbid) through a temperature jump and reached a shrunken state (transparent), i.e., an equilibrium state, over time. Moreover, the equilibrium degree of swelling decreased non-linearly with increasing temperature. Furthermore, different thermoresponsive sites were photopatterned on the organogel through the photodimerization of the coumarin unit. The organogels consisting of homopolymers of coumarin-containing methacrylate exhibited unique thermo- and photoresponsivities and behaved as monofunctional dual-stimuli-responsive organogels.

Systematic evaluation of pH and thermoresponsive poly(n-isopropylacrylamide-chitosan-fluorescein) microgel

e-Polymers ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 399-408 ◽  
Author(s):  
Pedro Hernández ◽  
Armando Lucero-Acuña ◽  
Cindy Alejandra Gutiérrez-Valenzuela ◽  
Ramón Moreno ◽  
Reynaldo Esquivel
Keyword(s):  
Biomedical Application ◽  
Systematic Evaluation ◽  
Molar Ratio ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Scanning Calorimetry ◽  
Molar Ratios ◽  
Stimuli Responsive Polymers ◽  
Wide Range ◽  
Low Molecular Weight Chitosan

AbstractThe interesting properties of stimuli-responsive polymers lead to a wide range of possibilities in design and engineering of functional material for the biomedical application. A systematic approach focused on the evaluation of the physical properties of multiresponse (pH and temperature) PNIPAM was reported in this work. The effect of three different molar ratios of poly(n-isopropylacrylamide): chitosan (1:49, 1:99 and 1:198) were evaluated and labeled correspondingly as PC1F, PC2F, and PC3F. An increase in the lower critical solution temperature (LCST) of sample PC1F (34°C) was observed by differential scanning calorimetry (DSC). The presence of low molecular weight chitosan (LMWC) full-interpenetrating polymer (Full-IPN) segments in poly(n-isopropylacrylamide) was confirmed by Fourier-transform infrared spectroscopy (FT-IR). The hydrogel’s water capture was analyzed by two models of swelling, the power law model and a model that considers the relaxation of polymeric chains of the hydrogel, finding good correlations with experimental data in both cases. Sample PC3F resulted with higher swellability, increasing the weight of the hydrogel around seven times. Hydrogel pH-sensibility was confirmed placing the samples at different pH environments, with an apparent increase in swellability for acidic conditions, confirming the highest swellability for sample PC3F, due to hydrogen bonds boosted by chitosan high molar ratio. Based on these results, the hydrogel obtained has potential as a thermo-pH triggered hydrogel in drug delivery applications.

Diffusion Kinetics of BSA Protein in Stimuli Responsive Hydrogels

2010 ◽  
Vol 297-301 ◽  
pp. 664-669 ◽  
Author(s):  
A.A. Naddaf ◽  
H.J. Bart ◽  
I. Tsibranska
Keyword(s):  
Moving Boundary ◽  
Calculated Data ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Dense Layer ◽  
Diffusion Kinetics ◽  
Stimuli Responsive ◽  
Different Temperatures ◽  
Thermosensitive Hydrogels ◽  
Kinetics Of

A two-dimensional diffusion mathematical model with moving boundary conditions was developed to evaluate the diffusion kinetics of bovine serum albumin (BSA) through the network of poly(N-isopropylacrylamide) hydrogel (poly(NIPAAm)). These thermosensitive hydrogels were experimentally tested for their response to BSA by exposing the hydrogel disc-shaped geometry to different temperatures and varied protein concentration. The BSA release, which is coupled with hydrogel shrinking when reaching the low critical solution temperature (LCST) of poly(NIPAAm), could be satisfactory described by the model. During the early course of hydrogel shrinking, the hydrogel outermost surface layer collapses to form a dense layer in comparison to the interior bulk matrix. Due to the hydrophobic interaction between polymer chains and polymer protein, the formed layer is thick and dense enough to restrict the outward permeation of entrapped BSA molecules from the hydrogel interior, which greatly slows down the release rate. A good agreement between experimental and calculated data was achieved.

scholarly journals How to manipulate the upper critical solution temperature (UCST)?

2017 ◽  
Vol 8 (1) ◽  
pp. 220-232 ◽  
Author(s):  
Jukka Niskanen ◽  
Heikki Tenhu
Keyword(s):  
Aqueous Solutions ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Critical Solution Temperature ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Ph Influence ◽  
Counter Ions ◽  
Upper Critical Solution Temperature

In this mini-review, we discuss multi-stimuli-responsive polymers, which exhibit upper critical solution temperature (UCST) behavior mainly in aqueous solutions, and focus on examples where counter ions, electricity, light, or pH influence the thermoresponsiveness of these polymers.

scholarly journals The Study of pH Effects on Phase Transition of Multi-Stimuli Responsive P(NiPAAm-co-AAc) Hydrogel Using 2D-COS

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1447
Author(s):  
Yeonju Park ◽  
Minkyoung Kim ◽  
Hae-jin Chung ◽  
Ah-hyun Woo ◽  
Isao Noda ◽  
...  
Keyword(s):  
Phase Transition ◽  
Principal Component ◽  
Correlation Spectroscopy ◽  
Cooh Group ◽  
Ph Effects ◽  
Two Dimensional ◽  
Stimuli Responsive ◽  
Stimuli Responsive Polymers ◽  
Transition Mechanism ◽  
Gradient Mapping

The temperature and mechanism of phase transition of poly(N-isopropylacrylamide-co-acrylic acid) [P(NiPAAm-co-AAc)], which is one of the multi-stimuli responsive polymers, were investigated at various pHs using infrared (IR) spectroscopy, two-dimensional (2D) gradient mapping, and two-dimensional correlation spectroscopy (2D-COS). The determined phase transition temperature of P(NiPAAm-co-AAc) at pH 4, 3, and 2 based on 2D gradient mapping and principal component analysis (PCA) showed that it decreases with decreasing pH, because COOH group in AAc changes with variation of pH. The results of 2D-COS analysis indicated that the phase transition mechanism of P(NiPAAm-co-AAc) hydrogel at pH4 is different from that at pH2 due to the effect of COOH group of AAc.

scholarly journals Chiral recognition of macromolecules with cyclodextrins: pH- and thermosensitive copolymers from N-isopropylacrylamide and N-acryloyl-D/L-phenylalanine and their inclusion complexes with cyclodextrins

2011 ◽  
Vol 7 ◽  
pp. 204-209 ◽  
Author(s):  
Sabrina Gingter ◽  
Ella Bezdushna ◽  
Helmut Ritter
Keyword(s):  
Ph Value ◽  
High Sensitivity ◽  
2D Nmr ◽  
Water Soluble ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
2D Nmr Spectroscopy ◽  
Enantioselective Recognition ◽  
Stimuli Responsive Polymers ◽  
Thermosensitive Copolymers

In the present work we report the enantioselective recognition of water soluble stimuli-responsive polymers bearing phenylalanine moieties via host-guest interaction with β-cyclodextrin and randomly-methylated-β-cyclodextrin (RAMEB-CD). We synthesised N-acryloyl-D/L-phenylalanine monomers (2 D , 2 L ) which were then copolymerised under free radical conditions with N-isopropylacrylamide (NIPAAm). The resulting copolymers 3 D and 3 L exhibit a lower critical solution temperature (LCST) of 25 °C. As a further benefit, the presence of a free carboxylic group in the copolymer system gives a high sensitivity to the pH value in respect to the LCST value. The enantioselective recognition of the side groups of copolymers 3 D and 3 L and their solubility behaviour were investigated by dynamic light scattering and 2D NMR spectroscopy, respectively.

scholarly journals Thermoresponsive Polypeptoids

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2973
Author(s):  
Dandan Liu ◽  
Jing Sun
Keyword(s):  
Phase Transition ◽  
Functional Groups ◽  
Synthetic Methods ◽  
Stimuli Responsive ◽  
Thermoresponsive Polymers ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Reversible Phase Transition ◽  
Polymer Architectures ◽  
Reversible Phase

Stimuli-responsive polymers have been widely studied in many applications such as biomedicine, nanotechnology, and catalysis. Temperature is one of the most commonly used external triggers, which can be highly controlled with excellent reversibility. Thermoresponsive polymers exhibiting a reversible phase transition in a controlled manner to temperature are a promising class of smart polymers that have been widely studied. The phase transition behavior can be tuned by polymer architectures, chain-end, and various functional groups. Particularly, thermoresponsive polypeptoid is a type of promising material that has drawn growing interest because of its excellent biocompatibility, biodegradability, and bioactivity. This paper summarizes the recent advances of thermoresponsive polypeptoids, including the synthetic methods and functional groups as well as their applications.

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