pHEMA hydrogels

Passos, Marcele Fonseca; Dias, Danielle Rodrigues; Bastos, Gilmara N. T.; Jardini, André Luiz; Benatti, Ana Carolina Bueno; Dias, Carmen Gilda Barroso Tavares; Filho, Rubens Maciel

doi:10.1007/s10973-016-5329-6

Cited by 59 publications

(19 citation statements)

References 33 publications

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“…This value is close to the literature value of PHEMA found in our previous publication, i.e., 89 ± 3.1 kJ/mol (R 2 = 0.997) [18], and also near to that of PMMA, i.e., 84 kJ/mol [21]. It should be noted that lower values have been reported in the literature (i.e., 56.7 [10]; 63.6 [12]; 73.2 kJ/mol [11]), though they have been estimated by integral data on non-isothermal polymerization that have been proven to be not strictly correct. In addition, the commercially-available monomer, HEMA, used by different groups of authors is not pure and includes inhibitors or other products, which affect the polymerization kinetics.…”

Section: Of 19supporting

confidence: 90%

“…It offers the advantage of continuous recording of the variation of the reaction rate with time through the measurements of the amount of heat released, since additional reactions are exothermic. This technique has been also used for recording the polymerization kinetics of HEMA and its copolymers with some dimethacrylate monomers (such as ethylene glycol dimethacrylate (EGDMA) or diethylene glycol dimethacrylate (DEGDMA)) [10][11][12][13][14]. Modeling of polymerization kinetics has been carried out using semi-empirical models, such as those developed for resins-curing [11] or based on the isoconversional principle [10].…”

Section: Introductionmentioning

confidence: 99%

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Polymerization Kinetics of Poly(2-Hydroxyethyl Methacrylate) Hydrogels and Nanocomposite Materials

Achilias

Sıafaka

2017

Processes

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Hydrogels based on poly(2-hydroxyethyl methacrylate) (PHEMA) are a very important class of biomaterials with several applications mainly in tissue engineering and contacts lenses. Although the polymerization kinetics of HEMA have been investigated in the literature, the development of a model, accounting for both the chemical reaction mechanism and diffusion-controlled phenomena and valid over the whole conversion range, has not appeared so far. Moreover, research on the synthesis of nanocomposite materials based on a polymer matrix has grown rapidly recently because of the improved mechanical, thermal and physical properties provided by the polymer. In this framework, the objective of this research is twofold: to provide a kinetic model for the polymerization of HEMA with accurate estimations of the kinetic and diffusional parameters employed and to investigate the effect of adding various types and amounts of nano-additives to the polymerization rate. In the first part, experimental data are provided from Differential Scanning Calorimetry (DSC) measurements on the variation of the reaction rate with time at several polymerization temperatures. These data are used to accurately evaluate the kinetic rate constants and diffusion-controlled parameters. In the second part, nanocomposites of PHEMA are formed, and the in situ bulk radical polymerization kinetics is investigated with DSC. It was found that the inclusion of nano-montmorillonite results in a slight enhancement of the polymerization rate, while the inverse holds when adding nano-silica. These results are interpreted in terms of noncovalent interactions, such as hydrogen bonding between the monomer and polymer or the nano-additive. X-Ray Diffraction (XRD) and Fourier Transform Infra-Red (FTIR) measurements were carried out to verify the results.

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Section: Of 19supporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Polymerization Kinetics of Poly(2-Hydroxyethyl Methacrylate) Hydrogels and Nanocomposite Materials

Achilias

Sıafaka

2017

Processes

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“…is property implies similar features to the human body soft tissue. In addition, hydrogels are biocompatible; they have low immunogenicity and allow a fast mass transfer between cells and the surroundings [7][8][9][10]. Currently, hydrogels are used as scaffolds for tissue engineering [11], controlled drug delivery [12], artificial articular cartilage, and intelligent devices (that responds to external stimuli, such as pH and temperature) [10,13], and it may provide the initial structural support required to retain cells in the defective area for cell metabolism, growth, differentiation, and new matrix synthesis [14].…”

Section: Introductionmentioning

confidence: 99%

“…Poly(2-hydroxyethyl methacrylate) (PHEMA) stands out in medical applications among the materials investigated for hydrogel obtainment [8,16,17]. It was first studied by Witcherle and Lim [18] in the development of contact lenses.…”

Section: Introductionmentioning

confidence: 99%

“…It was first studied by Witcherle and Lim [18] in the development of contact lenses. PHEMA is nonbiodegradable, has high hydrophilicity, and can be easily obtained [8]. Cartilage tissue engineering has been studied using several types of hydrogels, made of natural (e.g., chitosan and collagen) or synthetic polymers (e.g., polyvinyl alcohol and polyethylene glycol) [19].…”

Section: Introductionmentioning

confidence: 99%

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PHEMA Hydrogels Obtained by Infrared Radiation for Cartilage Tissue Engineering

Passos

Carvalho

Rodrigues³

et al. 2019

International Journal of Chemical Engineering

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Although the exposure of polymeric materials to radiation is a well-established process, little is known about the relationship between structure and property and the biological behavior of biomaterials obtained by thermal phenomena at 1070 nm wavelength. This study includes results concerning the use of a novel infrared radiation source (ytterbium laser fiber) for the synthesis of poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel in order to produce medical devices. The materials were obtained by means of free radical polymerization mechanism and evaluated regarding its cross-linking degree, polymer chain mobility, thermal, and mechanical properties. Their potential use as a biomaterial toward cartilage tissue was investigated through incubation with chondrocytes cells culture by dimethylmethylene blue (DMMB) dye and DNA quantification. Differential scanning calorimetry (DSC) results showed that glass transition temperature (Tg) was in the range 103°C–119°C, the maximum degree of swelling was 70.8%, and indentation fluency test presented a strain of 56%–85%. A significant increase of glycosaminoglycans (GAGs) concentration and DNA content in cells cultured with 40 wt% 2-hydroxyethyl methacrylate was observed. Our results showed the suitability of infrared laser fiber in the free radicals formation and in the rapid polymer chain growth, and further cross-linking. The porous material obtained showed improvements concerning cartilage tissue regeneration.

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Smart Polymers for Microscale Machines

Tan

Davis

Cappelleri

2020

Adv Funct Materials

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Microscale machines are able to perform a number of tasks like micromanipulation, drug‐delivery, and noninvasive surgery. In particular, microscale polymer machines that can perform intelligent work for manipulation or transport, adaptive locomotion, or sensing are in‐demand. To achieve this goal, shape‐morphing smart polymers like hydrogels, liquid crystalline polymers, and other smart polymers are of great interest. Structures fabricated by these materials undergo mechanical motion under stimulation such as temperature, pH, light, and so on. The use of these materials renders microscale machines that undergo complex stimuli‐responsive transformation such as from planar to 3D by combining spatial design like introducing in‐plane or out‐plane differences. During the past decade, many techniques have been developed or adopted for fabricating structures with smart polymers including microfabrication methods and the well‐known milestone of 4D printing, starting in 2013. In this review, the existing or potential active smart polymers that could be used to fabricate active microscale machines to accomplish complex tasks are summarized.

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pHEMA hydrogels

Cited by 59 publications

References 33 publications

Polymerization Kinetics of Poly(2-Hydroxyethyl Methacrylate) Hydrogels and Nanocomposite Materials

Polymerization Kinetics of Poly(2-Hydroxyethyl Methacrylate) Hydrogels and Nanocomposite Materials

PHEMA Hydrogels Obtained by Infrared Radiation for Cartilage Tissue Engineering

Smart Polymers for Microscale Machines

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