Controlling PVA Hydrogels with γ-Cyclodextrin

Hernández, Rebeca; Rusa, Mariana; Rusa, Cristian C.; López, Daniel; Mijangos, Carmen; Tonelli, Alan E.

doi:10.1021/ma048375i

Cited by 56 publications

(41 citation statements)

References 20 publications

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“…PVA diffractogram presents a broad peak of high intensity (115. 40 a.u) at about 2θ=20 0 , comparable to the one presented in literature [31,32], indicating its crystalline structure. The breadth of the peak at 2θ=20 0 and the lack of other main peaks on 2θ interval between 5-60 0 , suggests that PVA presents a reduced degree of crystallinity.…”

Section: Tabsupporting

confidence: 85%

Biodegradable poly(vinyl alcohol-lactic acid-aspartic acid) copolymers

Tudorachi

Lipşa

2009

E-Polymers

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Abstract:The aliphatic polyesters: polylactides (PLA), polyglycolides (PGA), poly( -caprolactone) (PCL) as well as their copolymers especially, poly(lactide-coglycolide) (PLGA), poly(vinyl alcohol) (PVA), chitosan, dextran and starch occupy first place among biodegradable, biocompatible and non-toxic polymers. PVA, with different molecular weights, hydrolysis degree, tacticity, crystallinity, and due to the abundance of pendant hydroxy groups in the backbone is capable of several grafting and cross-linking. The present study concerns the synthesis of graft copolymers poly(vinyl alcohol) with lactic acid (LA) and aspartic acid (Asp). The modification reaction of poly(vinyl alcohol) with lactic and aspartic acid was achieved by solution polycondensation using dioxane/water (3/1) as solvent mixture, different molar ratios PVA/LA/Asp and manganese acetate as catalyst: Mn(CH 3 COO) 2 4H 2 O. The copolymers were characterized by FTIR, 1 H-NMR, thermal stability (DSC, TG), elemental analysis, wide angle X-ray diffraction (WAXD). The average particle size and zeta potential for aqueous dispersions of copolymers, solubility in organic solvents and biodegradation testing on agar-agar medium inoculated with a fungus Chaetomium globosum class MO5 stock, were studied.

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Section: Tabsupporting

confidence: 85%

Biodegradable poly(vinyl alcohol-lactic acid-aspartic acid) copolymers

Tudorachi

Lipşa

2009

E-Polymers

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“…While the channel arrangement can be converted into a cage structure by water sorption/desorption cycles, with an intermediated amorphous state, the latter usually results from rapid recrystallization of CDs. After reaching sorption equilibrium, CD molecules undergo a slow rearrangement to the cage structure with defined water content [66]. Similar patterns are generally found in the crystal structures of CD inclusion complexes [66].…”

Section: Common Arrangements In CD Aggregatessupporting

confidence: 68%

“…After reaching sorption equilibrium, CD molecules undergo a slow rearrangement to the cage structure with defined water content [66]. Similar patterns are generally found in the crystal structures of CD inclusion complexes [66]. When the entire guest molecule is small enough to be included inside a single CD cavity, cage-type structures are formed.…”

Section: Common Arrangements In CD Aggregatessupporting

confidence: 57%

See 1 more Smart Citation

Aggregation of Cyclodextrins: Fundamental Issues and Applications

Cova¹,

Cruz²,

Valente³

et al. 2018

Cyclodextrin - A Versatile Ingredient

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The aggregation of cyclodextrins (CD) in aqueous solution is an old, yet still vastly unexplored topic that has been studied at least since the 1980s. At that time, few authors took into consideration the possibility of formation of aggregates for the interpretation of thermodynamic and thermophysical properties of CDs in aqueous solution. The aggregates appear at quite low CD concentrations and seem to encompass only a small number of CD molecules. They also occur in water in the presence of hydrophobic or amphiphilic moieties, including surfactants, assuming a preassembled state with the hydrophobic chains threading through one or two CDs. After a long period in which it has been neglected, CD aggregation is now a hot topic and one far from gathering consensus. In this chapter, a timely and critical review on the phenomenon of CD aggregation and the respective supramolecular properties, including some computational rationales, will be presented. A comprehensive summary of CD aggregates studied to date, indicating the formation conditions, characterization techniques, and applications, is also provided.

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“…We prepared and characterized poly(vinyl alcohol) (PVA) hydrogels formed during freeze-thaw (F-T) cycles of their aqueous solutions, which also contained γ-CD [43]. Crystalline inclusion compound (IC) formation was observed between PVA and γ-CD in these gels at low concentrations of γ-CD (γ-CD:PVA molar ratios <1 : 25).…”

Section: Pva Gels [43]mentioning

confidence: 99%

Molecular Processing of Polymers with Cyclodextrins

Tonelli

2009

Advances in Polymer Science

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We summarize our recent studies employing the cyclic starch derivatives called cyclodextrins (CDs) to both nanostructure and functionalize polymers. Two important structural characteristics of CDs are taken advantage of to achieve these goals. First the ability of CDs to form noncovalent inclusion complexes (ICs) with a variety of guest molecules, including many polymers, by threading and inclusion into their relatively hydrophobic interior cavities, which are roughly cylindrical with diameters of ∼0.5 − 1.0 nm. α-, β-, and γ-CD contain six, seven, and eight α-1,4-linked glucose units, respectively. Warm water washing of polymer-CD-ICs containing polymer guests insoluble in water or treatment with amylase enzymes serves to remove the host CDs and results in the coalescence of the guest polymers into solid samples. When guest polymers are coalesced from the CD-ICs by removing their host CDs, they are observed to solidify with structures, morphologies, and even conformations that are distinct from bulk samples made from their solutions and melts. Molecularly mixed, intimate blends of two or more polymers that are normally immiscible can be obtained from their common CD-ICs, and the phase segregation of incompatible blocks can be controlled (suppressed or increased) in CD-IC coalesced block copolymers. In addition, additives may be more effectively delivered to polymers in the form of their crystalline CD-ICs or soluble CD-rotaxanes. Secondly, the many hydroxyl groups attached to the exterior rims of CDs, in addition to conferring water solubility, provide an opportunity to covalently bond them to polymers either during their syntheses or via postpolymerization reactions. Polymers containing CDs in their backbones or attached to their side chains are observed to more readily accept and retain additives, such as dyes and fragrances. Processing with CDs can serve to both nanostructure and functionalize polymers, leading to greater understanding of their behaviors and to new properties and applications.

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Controlling PVA Hydrogels with γ-Cyclodextrin

Cited by 56 publications

References 20 publications

Biodegradable poly(vinyl alcohol-lactic acid-aspartic acid) copolymers

Biodegradable poly(vinyl alcohol-lactic acid-aspartic acid) copolymers

Aggregation of Cyclodextrins: Fundamental Issues and Applications

Molecular Processing of Polymers with Cyclodextrins

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