Lower Critical Solution Temperature Properties of N‐Isopropylacrylamide‐Based Pseudopolyrotaxanes by Complexation with Cucurbituril[6]

Abstract

Pseudopolyrotaxanes 4a and 5a are synthesized by two paths: a) directly from the pseudorotaxane, and b) by complexing with cucurbituril (CB[6]) in water at room temperature after the polymerization. Free radical copolymerization with CB[6] (un)complexed monomer and N‐isopropylacrylamide (NIPAAM) is carried out using a redox initiator in aqueous media at room temperature. The properties of pesudorotaxanes (4a and 5a) and polymers (4 and 5) are investigated by TGA, DSC, and turbidity measurements. The lower critical solution temperatures of the NIPAAM‐containing copolymers and CB[6] are significantly higher than those of pure NIPAAM copolymers. The pseudopolyrotaxanes 4a and 5a have a higher thermal stability, as a result of threading of the CB[6] rings onto the polymer side groups.magnified image

Synthesis of chiral amphiphilic diblock copolymers via consecutive RAFT polymerizations and their aggregation behavior in aqueous solution

“…Such difference in this work may be due to the hydrophobic comonomer in the amphiphilic copolymer, VBCPG, which had the biological activity part of 1,2;3,4‐di‐O‐isopropylidene‐ D ‐galactopyranose (PG) in structure. PG was a little soluble in water, when reacted with VB then polymerized into poly(VBCPG) which had the hydrophobic main chain (polystyrene backbone) but with the soluble chiral pendent units of PG which could wrap the polystyrene backbone and thread the hydrophobic character of the backbone 47. In another word, the chiral amphiphilic diblock copolymer, although had the hydrophobic block of poly(VBCPG), but the hydrophobic part could be shielded, so the LCST of poly(VBCPG)‐ b ‐poly(NIPAAM) was higher than the homopolymer of NIPAAM.…”

Aggregation and thermal gelation of N-isopropylacrylamide based cucurbit[7]uril side-chain polypseudorotaxanes with low pseudorotaxane content

“…Based on the rigid-so alternate structure of the polypseudorotaxanes, the drastic increase in the hydrodynamic radius was explained by the following mechanism (see Fig. 2b): unlike the increase on rigidity across whole polymer chain of polypseudorotaxanes with high pseudorotaxane content, [34][35][36][37][38][39] with these NIPAA based CB [7] polypseudorotaxanes, due to their low pseudorotaxane content, the rigid CB [7] pseudorotaxane segments only partially the entanglement of polymer chain, making the polypseudorotaxane structure more outstretched. The remaining so segments of the polypseudorotaxanes acted as so-coils and are still capable of entangling.…”

“…9,28-39 Among them, construction of CB based side-chain poly(pseudo) rotaxanes through (co)polymerization is well established. [34][35][36][37][38][39] CB based side-chain polypseudorotaxanes were rstly reported by Tan et al; 36 here the polypseudorotaxanes were synthesized through the polymerization of protonated diaminobutane based monomers to construct the polymer backbones, followed by threading CB [6] on the side-chain of the polymers. These polypseudorotaxanes displayed higher conformational rigidity than the pristine polymer due to the large size of CB [6].…”

“…Subsequently Ritter et al and Nakamoto et al reported polypseudorotaxanes with N-isopropyacrylamide (NIPAA) based copolymer backbones which threaded with CB [6] and CB [7] respectively. 37,38 The formation of polypseudorotaxanes changes the aggregation behavior of pristine copolymers. These polypseudorotaxanes demonstrated an increase in low critical solution temperature (LCST) and loss of turbidity.…”

Temperature and pH-responsive properties of poly(styrene-co-maleic anhydride)-grafting poly(oxypropylene)-amines

“…The temperature-dependent (LCST) absorption of the UV-vis spectra [33] Aromatic functionalities on the SMA backbone in an aggregated phase are examined using UV-vis spectroscopy. The relative intensity change at different temperatures represents the phase transformation or LCST of these SMA-POP copolymers in solution.…”