Effects of graft length and density of well‐defined graft polymers on the thermoresponsive behavior and self‐assembly morphology

Abstract

A series of well‐defined thermoresponsive graft polymers with different lengths and graft densities, poly(glycidyl methacrylate)‐graft‐poly(N‐isopropylacrylate) (PGMA‐g‐PNIPAM), were successfully prepared by combination of controlled/living free radical polymerization and click chemistry. Effects of grafting length and density on the thermoresponsive behavior, aggregating mean diameter, and self‐assembly morphology are systematically investigated. The thermosensitive characteristics of graft polymers in aqueous solution prove that the length and graft density had positive co‐relationship with the lower critical solution temperature value and mean diameter of micelles as well as the size distribution, while the effect of graft length of polymers is more significant than that of density. Transmission electron microscopy analysis shows that the conformations of PGMA45‐g‐PNIPAM20 and PGMA45‐g‐PNIPAM46 with longer length and bigger grafting density in aqueous solutions are spherical nanoparticles with the increasing trend of the diameters, while that of PGMA45‐g‐PNIPAM(73, 50%) shows a spherical‐like morphology, which indicates that the graft length and density have a significant effect on the mean diameter of micelle but not on the self‐assembly morphology. These results reveal that to obtain desired thermoresponsive behavior and self‐assembly morphology of functional polymers, it is essential to design and fabricate the structure of graft polymers with proper length and graft density. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2442–2453

Synthesis, micellization, and thermally-induced macroscopic micelle aggregation of poly(vinyl chloride)-g-poly(N-isopropylacrylamide) amphiphilic copolymer

“…5b). These results are in good accordance with the thermoresponsive gra copolymers reported in literatures such as poly(methyl-methacrylate)-g-PNI-PAM, 28 poly(glycidyl methacrylate)-g-PNIPAM, 30 and PCL-g-PNIPAM. 31,32 The thermally-triggered micelle aggregation of PVC-g-PNIPAM is reversible.…”

“…Incorporating a hydrophobic segment in PNIPAM can change its LCST and phase transition behavior and also be used to prepare thermoresponsive copolymer micelles. With the development of controlled/living free radical polymerization (CLRP), many well-dened amphiphilic diblock, [7][8][9][10][11][12][13] triblock, [14][15][16][17][18][19][20][21] star-shaped block, [22][23][24][25][26] and gra [27][28][29][30][31][32] copolymers consisting of the PNIPAM segments have been prepared and their selfassembling, thermoresponsive behavior have been investigated. These linear and star-shaped block copolymers can be synthesized with combination of the CLRP of N-isopropylacrylamide (NIPAM) and the living polymerization of other monomers, in which the chain end functionalization of the rst block is necessary for initiating the polymerization of second block.…”

“…28 Jiang et al have prepared the poly-(glycidyl-methacrylate)-g-PNIPAM copolymers with different gra lengths and densities by CLRP and click chemistry. 30 Li et al have synthesized the poly(3-caprolactone)-g-PNIPAM (PCLg-PNIPAM) copolymers with the combination of ring-opening polymerization, ATRP, and click chemistry using the graingfrom and graing-to strategies. 31,32 The amphiphilic copolymers containing hydrophilic PNI-PAM segments can form the core-shell micelles or vesicles in aqueous solution below LCST.…”

Synthesis and self‐assembly of thermoresponsive block‐graft fluoropolymer as well as its tunable wettability surface

“…The S −1‐Butyl‐ S ′‐( a, a ′‐dimethyl‐ a ″‐acetic acid) trithiocarbonate was synthesized according to the literature, and its protected alkynyl hydrogen groups was prepared by trimethyl chlorosilane . And the homopolymer PHFBMA 74 , PHFBMA 74 ‐ b ‐PGMA 36 and ring‐opened copolymer PHFBMA 74 ‐ b ‐PGMA 36 (OH/N 3 ) were prepared according to our previous work, and homopolymer Alkynyl ‐PNIPAM 48 with alkyne groups on the main chain was synthesized according to our reference …”

Multistimuli-Responsive Optical Hydrogel Nanomembranes to Construct Planar Color Display Boards for Detecting Local Environmental Changes

“…The experimental and theoretical results show that the synthesized thermoresponsive insulating layer showed a large shrink/expand behavior at the range of 20–30 °C, while it was stable at temperatures under 19 and over 35 °C. The temperature range where the thickness changes is a bit different from the typical thermal transition range of the system comprising the PNIPAm homopolymer, which is possibly attributable to the incorporation of other components such as the GMA unit and cross-linker exhibiting different polarities. − In addition, the dynamic color change was reversible. Upon temperature decrease (cooling), the λ peak reversibly and precisely followed the λ peak values measured during heating.…”