Toward an understanding of thermoresponsive transition behavior of hydrophobically modified N-isopropylacrylamide copolymer solution

Cao, Zhiqiang; Liu, Wenguang; Gao, Peng; Yao, Kangde; Li, Hexian; Wang, Guochang

doi:10.1016/j.polymer.2005.04.050

Cited by 70 publications

(57 citation statements)

References 35 publications

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“…A similar phenomenon was reported in our previous work on a poly[(N-isopropylacrylamide)-co-(vinyl laurate)] copolymer. [26] It is noteworthy that PHEMA 40 in this study was insoluble in water (pH 6.0) and insensitive to temperature. While in Armes and co-workers' work, [30] PHEMA homopolymers with degrees of polymerization between 20 and 45 were shown to be temperature sensitive in aqueous solutions at pH 6.5.…”

Section: Thermoresponsive Behaviors Of Nipaam/hema Triblock Copolymermentioning

confidence: 68%

Effect of Block Order of ABA‐ and BAB‐Type NIPAAm/HEMA Triblock Copolymers on Thermoresponsive Behavior of Solutions

Zhao

Liu

Chen

et al. 2007

Macro Chemistry & Physics

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ABA and BAB triblock thermoresponsive copolymers (A = N‐isopropylacrylamide, B = 2‐hydroxyethyl methacrylate) have been synthesized by atom transfer radical polymerization (ATRP). BAB is shown to exhibit a higher transition temperature and a good solubility in water compared to ABA with the same composition and concentration. The differences are attributed to the distinct micellar structure, which is regulated by the block order of the copolymers. It is speculated that ABA and BAB copolymers separately form branch and flower micelles in water, which mainly influence the course of phase transition. The moduli of the ABA copolymer solution are higher than those of the BAB above gel point. In terms of hypothesized micelle models, it is proposed that the ‘branch’ micelles of the ABA solution preferably form more physical interconnections.

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Section: Thermoresponsive Behaviors Of Nipaam/hema Triblock Copolymermentioning

confidence: 68%

Effect of Block Order of ABA‐ and BAB‐Type NIPAAm/HEMA Triblock Copolymers on Thermoresponsive Behavior of Solutions

Zhao

Liu

Chen

et al. 2007

Macro Chemistry & Physics

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“…It has been reported previously that the introduction of hydrophobic components may decrease the LCST of PNIPAAm, resulting from the facilitation of the dehydration of copolymer chains. 32 Comparing the copolymers of N82-A3, N88-A3, and N94-A3, it could be perceived that the LCST increased remarkably with an increase of the NIPAAm content when the R ratio (AAc/HEMAPCL ratio) was kept constant. In contrast, when copolymers had the same NIPAAm content (88% mole ratio), increasing the R ratio appeared to slightly increase the LCST.…”

Section: Sol-gel Transition Analysismentioning

confidence: 99%

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Lian

Xiao²,

Bian³

et al. 2012

IJN

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A series of biodegradable thermosensitive copolymers was synthesized by free radical polymerization with N-isopropylacrylamide (NIPAAm), acrylic acid (AAc) and macromer 2-hydroxylethyl methacrylate-poly(ε-caprolactone) (HEMAPCL). The structure and composition of the obtained terpolymers were confirmed by proton nuclear magnetic resonance spectroscopy, while their molecular weight was measured using gel permeation chromatography. The copolymers were dissolved in phosphate-buffered saline (PBS) solution (pH = 7.4) with different concentrations to prepare hydrogels. The lower critical solution temperature (LCST), cloud point, and rheological property of the hydrogels were determined by differential scanning calorimetry, ultraviolet-visible spectrometry, and rotational rheometry, respectively. It was found that LCST of the hydrogel increased significantly with the increasing NIPAAm content, and hydrogel with higher AAc/HEMAPCL ratio exhibited better storage modulus, water content, and injectability. The hydrogels were formed by maintaining the copolymer solution at 37°C. The degradation experiment on the formed hydrogels was conducted in PBS solution for 2 weeks and demonstrated a less than 20% weight loss. Scanning electron microscopy was also used to study the morphology of the hydrogel. The copolymer with NIPAAm/AAc/HEMAPCL ratio of 88:9.6:2.4 was bioconjugated with type I collagen for the purpose of biocompatibility enhancement. In-vitro cytotoxicity of the hydrogels both with and without collagen was also addressed.

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“…[15,16] A great deal of attention has been placed on the thermo-responsive properties and applications of various copolymers of PNIPAM with acrylic acid, methacrylic acid, hydroxyethyl methacrylate, acrylamide, maleic anhydride, polyethyleneglycol derivatives, vinyl laurate, dodecyl groups, as well as other functional comonomers. [17][18][19][20][21][22][23][24][25][26] Recently, hydrophobically modified water-soluble polymers have received a great deal of experimental and theoretical interests. [27] Hydrophobically modified PNIPAM has been studied and used in designing materials for various applications such as drug controlled-release systems, bioseparations, and surface modification.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of a Novel Thermo‐Sensitive Copolymer of N‐Isopropylacrylamide and Dibenzo‐18‐crown‐6‐diacrylamide

Chu

et al. 2006

Macromol. Rapid Commun.

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Summary: A series of novel, thermo‐sensitive copolymers with different molar ratios of N‐isopropylacrylamide (NIPAM) and hydrophobic cis‐dibenzo‐18‐crown‐6‐diacrylamide (cis‐DBCAm) were prepared via free‐radical copolymerization. cis‐DBCAm with polymerizable end groups was successfully synthesized by reacting the corresponding amino crown ether with acryloyl chloride. The copolymers were characterized by FT‐IR and elemental analysis, and the thermo‐sensitivities of the copolymers were evaluated by measuring their lower critical solution temperatures (LCSTs) in the absence or presence of various metal ions. The results indicated that incorporation of cis‐DBCAm lowered LCSTs, and that the LCSTs of the copolymers decreased with the increase in cis‐DBCAm content in the copolymers. When the cavities of the crown ether units captured either K+ or Cs+ ions, the LCST of the respective copolymer–metal ion complex was further decreased, whereas the capture of Na+ or Li+ ions did not have a significant influence on the LCSTs of the copolymers.Incorporation of cis‐DBCAm into PNIPAM resulted in a lower LCST. The LCST was decreased more when the cavities of the crown ether units captured K+ ions.magnified imageIncorporation of cis‐DBCAm into PNIPAM resulted in a lower LCST. The LCST was decreased more when the cavities of the crown ether units captured K+ ions.

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Toward an understanding of thermoresponsive transition behavior of hydrophobically modified N-isopropylacrylamide copolymer solution

Cited by 70 publications

References 35 publications

Effect of Block Order of ABA‐ and BAB‐Type NIPAAm/HEMA Triblock Copolymers on Thermoresponsive Behavior of Solutions

Effect of Block Order of ABA‐ and BAB‐Type NIPAAm/HEMA Triblock Copolymers on Thermoresponsive Behavior of Solutions

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Synthesis and Characterization of a Novel Thermo‐Sensitive Copolymer of N‐Isopropylacrylamide and Dibenzo‐18‐crown‐6‐diacrylamide

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