Aggregation-induced microgelation: a new approach to prepare gels in solution

Yang, Xuyan; Tong, Yin-Yin; Li, Zi‐Chen; Liang, Dehai

doi:10.1039/c0sm00257g

Cited by 13 publications

(15 citation statements)

References 56 publications

(57 reference statements)

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“…[1][2][3][4] Among the existing PVA-based systems, the chemical and physical hydrogels with controlled macroscopic properties are of particular interest, as successfully shown in biotechnological and biomedical applications. The properties of PVA gels depend on their structure at different levels, from nanostructure to supramolecular associations, and they can be tailored by modulating the initial PVA systems used to prepare the gels and the preparation conditions.…”

Section: Introductionmentioning

confidence: 99%

In situgelation of aqueous solutions of entangled poly(vinyl alcohol)

Bercea¹,

Morariu²,

Rusu

2013

Soft Matter

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Rheological behaviour of poly(vinyl alcohol) (PVA) aqueous systems was systematically investigated at 30 C for different concentrations, molecular weights and hydrolysis degrees. The viscosity of very dilute polymer solutions was studied by means of viscometry, while the concentrated solutions were analyzed by steady shear flow measurements. The limit between the entangled and non-entangled states of PVA aqueous solutions was determined as the crossover of two scaling laws describing the dependence of specific viscosity as a function of coil overlap parameter, c[h]. Then, physical gels with good elastic properties were prepared in situ by freezing/thawing/ageing (200 min per cycle) of entangled PVA solutions. The influence of each stage of the applied cryogenic treatment on the gel formation and elastic properties of the final network was followed by means of dynamic rheological measurements at low strain, in the linear domain of viscoelasticity. It was shown that the gel properties largely depend on the initial state of PVA solutions, as described by the c[h] value, and on the degree of hydrolysis, as well as on the thermal history, i.e., the number of cryogenic cycles, thawing rate, and ageing step. For a given coil overlap parameter, the elastic modulus of cryogels tends to a limiting value, which can be reached faster by adding an ageing sequence to the classical freezing/thawing cryogenic cycles. This maximum value of the elastic modulus increases with increasing the coil overlap value of the initial solution.

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Section: Introductionmentioning

confidence: 99%

In situgelation of aqueous solutions of entangled poly(vinyl alcohol)

Bercea¹,

Morariu²,

Rusu

2013

Soft Matter

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“…The synthesis and purification of MIPCTSA and Pac macro‐CTA was done using a procedure previously outlined in literature. 16 The latter reaction was carried out at two different temperatures with the same molar ratios of monomer, CTA and initiator in order to investigate the effect of decomposition of AIBN on the molecular weight distribution. For the synthesis of block copolymers, PVAc macro‐CTA2, NIPAM and AIBN were all dissolved in 1, 4‐dioxane in a flask and degassed by three freeze–vacuum–thaw cycles.…”

Section: Experimental Partmentioning

confidence: 99%

“…Controlled polymerization of VAc via RAFT technique was found to be possible by using xanthates in macromolecular design via interchange of xanthates (MADIX) process 12–14 and also dithiocarbamates 15 as RAFT agents. Recently, for an aggregation‐induced microgelation study of PVA‐ b ‐PNIPAM, a new difunctional initiator with an active halide group and xanthate group in the molecule was used to overcome abovementioned drawback in synthesis of PVAc‐ b ‐PNIPAM 16 which is the source of PVA‐ b ‐PNIPAM.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Poly(N‐isopropylacrylamide) and Poly(vinyl acetate) Diblock Copolymers via MADIX Process

Özgüç

Helvacıoğlu

Nugay

et al. 2013

Macromolecular Symposia

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The synthesis of diblock copolymers of poly(N‐isopropylacrylamide) (PNIPAM) and poly(vinyl acetate) (PVAc) was performed by macromolecular design via interchange of xanthates (MADIX) process. Following the preparation of methyl (isopropoxycarbonothioyl) sulfanyl acetate (MIPCTSA) as chain transfer agent, it was reacted with vinyl acetate to obtain PVAc macro‐chain transfer agent. Then, block copolymerization was completed by successive addition of N‐isopropylacrylamide (NIPAM). 1H NMR spectroscopy confirmed the presence of both blocks in the copolymer structure, with the expected composition based on the feed ratio. Size Exclusion Chromatography (SEC) was used to investigate the relative values of molecular characteristics. Only 20% of PVAc was converted to block copolymer. The resultant block copolymer structures were further examined in terms of their morphologies as well as critical micelle concentration (CMC) by using ESEM and Fluorescence Excitation Spectroscopic techniques, respectively. Morphological characterization confirmed amphiphilic block copolymer formation with the existence of mainly ca. 100 nm well distributed micelles. The thermo responsive amphiphilic behavior of the block copolymer solutions were followed by Dynamic Light Scattering (DLS) technique.

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“…Owing to the advantages such as nontoxic, biocompatible, excellent mechanical and physicochemical properties, biodegradable hydrogels are regarded as suitable materials for biomedical, pharmaceutical, environmental, and other applications . The effective means to manipulate the structure and properties of hydrogels include varying the polymer composition and controlling the crosslinking process .…”

Section: Introductionmentioning

confidence: 99%

Controllable synthesis of a novel poly(vinyl alcohol)-based hydrogel containing lactate and PEG moieties

Xiao

2013

Polym Eng Sci

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Tunable hydrogel that contained well‐defined poly(vinyl alcohol) (PVA), labile lactate groups, and hydrophilic poly(ethylene glycol) (PEG) segments was prepared through a combination of reversible addition‐fragmentation chain transfer (RAFT) polymerization and esterification reaction. A diol was prepared via the esterification between lactic acid (LA) and PEG. Then the diol was allowed to react with maleic anhydride to produce a diacid. Meanwhile, well‐defined PVA was synthesized by the alcoholysis of poly(vinyl acetate) (PVAc) obtained by RAFT polymerization of vinyl acetate. The hydrogels with tailor‐made structure were generated by crosslinking PVA with LA‐based diacid. The structures and properties of LA‐based intermediates and the hydrogels were characterized with Fourier transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Both LA‐based diol and diacid were semicrystalline and water‐soluble, their melting temperature and glass transition temperature were 52 and −51, 54 and −41°C, respectively. The polydispersity indexes of the precursor of PVA samples were within the range of 1.03–1.10. It was found that the thermal stability of hydrogel was higher than that of LA‐based diacid. Both the swelling and release properties of the hydrogels depend on the feeding ratio of PVA/LEM and the chain length of PVA, which reflected that the structure and properties of the hydrogels were controllable. POLYM. ENG. SCI., 54:1366–1371, 2014. © 2013 Society of Plastics Engineers

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Aggregation-induced microgelation: a new approach to prepare gels in solution

Cited by 13 publications

References 56 publications

In situgelation of aqueous solutions of entangled poly(vinyl alcohol)

In situgelation of aqueous solutions of entangled poly(vinyl alcohol)

Synthesis and Characterization of Poly(N‐isopropylacrylamide) and Poly(vinyl acetate) Diblock Copolymers via MADIX Process

Controllable synthesis of a novel poly(vinyl alcohol)-based hydrogel containing lactate and PEG moieties

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