Shape Memory Hydrogel based on a Hydrophobically‐Modified Polyacrylamide (HMPAM)/α‐CD Mixture via a Host‐Guest Approach

Abstract

A novel thermally sensitive shape memory (SM) hydrogel is prepared by block copoly-merization of a cationic surfactant monomer, dimethylhexadecyl[2-(dimethylamino)ethylmethacrylate]ammoniumbromide (C(16)DMAEMA), and acrylamide (AM) in the presence of α-cyclodextrin (α-CD) using N,N'-methylenebisacrylamide (MBA) as a crosslinker. XRD, solid state (13)C NMR, and DSC measurements show that the crystalline domains, induced by the hydrogen bonds between α-CDs threaded on the hydrophobic units of the polymer chains through the host-guest approach, can reversibly melt and crystallize at different temperatures. Rheological measurements show that both the elastic modulus G' and viscous modulus G'' drastically change due to the formation and dissolution of the crystalline domains. These thermo-sensitive crystalline domains serve as reversible physical crosslinks, endowing the hydrogel with excellent SM properties. Cyclic experiments show that the hydrogel can recover to almost 100% of the deformation in each cycle and can be reused several times.

Novel Macromolecular Emulsifiers as Coatings with Water‐Tolerant Antifogging Properties Based on Coumarin‐Containing Copolymeric Micelles

“…Under acidic conditions, i.e., pH < 3.94, O/W emulsion could be stabilized as a result of the protonation of DMAEMA unit, making the emulsifier surface more hydrophilic. When pH was adjusted to more neutral or basic conditions, i.e., pH > 5.80, deprotonation of DMAEMA unit could promote the formation of more lipophilic surface, so the phase inversion from O/W to W/O was observed. Nevertheless, as pH elevated over 9.86, the stability of emulsions significantly decreased and even demulsification occurred due to the disintegration of micelles.…”

Dynamic Macromolecular Material Design—The Versatility of Cyclodextrin‐Based Host–Guest Chemistry

“…[82] Reversible deactivation radical polymerization is exploited in some examples to synthesize tailored polymers containing multiple host/guest motifs.A b-CD triple linker and PDMA doubly end functionalized with Angewandte Chemie Reviews 8356 www.angewandte.org adamantyl groups was introduced by Ritter and co-workers to obtain supramolecular networks. [83] Thev ery important field of stimuli-responsive hydrogels has been explored by several research groups;f or example,r edox-responsive networks were described by Zhang and co-workers [84] as well as photoand redox-responsive hydrogels by Wang and co-workers.…”

Controlled Thermoreversible Formation of Supramolecular Hydrogels Based on Poly(vinyl alcohol) and Natural Phenolic Compounds

“…Supramolecular materials based on noncovalent bonds have attracted considerable attention in several fields due to their special characteristics such as self‐healing, shape memory, and stimuli‐responsive properties among others . Indeed, multiple hydrogen bonding are ideal reversible noncovalent interactions for preparing supramolecular networks combining high strength and excellent reversibility …”