I monomeri acrilici sono un gruppo di composti chimici che fungono da mattoncini per vari polimeri. Sono ampiamente utilizzati nella formulazione di plastiche, adesivi, rivestimenti e cosmetici grazie alla loro versatilità e alla capacità di formare materiali durevoli e flessibili. Nelle applicazioni cosmetiche, i monomeri acrilici sono apprezzati per le loro proprietà filmogene, addensanti ed emulsionanti, contribuendo alla stabilità e alle prestazioni dei prodotti di bellezza.
Composizione Chimica e Struttura
I monomeri acrilici includono varie strutture chimiche, come:
- Acido Acrilico: Un monomero di base che può essere polimerizzato per formare poliacrilato.
- Monomeri Metacrilati: Varianti come il metilmetacrilato, spesso utilizzate per creare film più durevoli.
- Acrilati Alchilici: Come l'acrilato di butile, che migliorano le proprietà di flessibilità e adesione.
Questi monomeri possiedono un gruppo vinilico (C=C) che consente la polimerizzazione, formando catene lunghe che conferiscono caratteristiche uniche ai materiali risultanti.
Proprietà Fisiche
Aspetto: Tipicamente liquidi o solidi chiari e incolori, a seconda del monomero specifico.
Solubilità: Generalmente solubili in solventi organici; alcuni possono essere solubili in acqua.
pH: Neutro o leggermente acido, a seconda del monomero specifico.
Odore: Può avere un leggero odore acre, a seconda del composto specifico.
Stabilità: Generalmente stabile in condizioni normali di conservazione; deve essere protetto da luce e umidità.
Processo di Produzione
Sintesi: I monomeri acrilici sono sintetizzati attraverso varie reazioni chimiche, spesso a partire dall'acido acrilico o dai suoi derivati.
Purificazione: I monomeri risultanti vengono purificati per rimuovere eventuali impurità e sottoprodotti, garantendo prodotti di alta qualità.
Formulazione: I monomeri acrilici possono essere miscelati con altri ingredienti e polimerizzati in situ per creare le formulazioni desiderate.
Applicazioni
Cosmetici: Utilizzati in prodotti per la cura della pelle, per capelli e nel makeup per le loro proprietà addensanti e filmogene, che migliorano la texture e la stabilità del prodotto.
Adesivi: Fungono da componente principale negli adesivi a pressione grazie alla loro forte adesione e flessibilità.
Rivestimenti: Comunemente utilizzati nella vernice e nei rivestimenti superficiali per migliorare la durevolezza e la lucentezza.
Considerazioni Ambientali e di Sicurezza
I monomeri acrilici sono generalmente considerati sicuri per l'uso nei cosmetici quando applicati secondo le linee guida raccomandate. Tuttavia, alcune persone possono sperimentare sensibilità o reazioni allergiche.(1)
Pratiche di approvvigionamento e formulazione responsabili sono essenziali per garantire che questi ingredienti siano privi di contaminanti nocivi e prodotti in modo sostenibile.
Bibliografia__________________________________________________________________________
(1) Chou M, Dhingra N, Strugar TL. Contact Sensitization to Allergens in Nail Cosmetics. Dermatitis. 2017 Jul/Aug;28(4):231-240. doi: 10.1097/DER.0000000000000301. PMID: 28719472.
Abstract. Ingredients found in the nail cosmetic industry, including but not limited to methacrylate and acrylate monomers, formaldehyde, and toluene sulfonamide-formaldehyde resin, can incite allergic contact dermatitis. An eczematous outbreak presents on areas surrounding the nail plate and may spread through contact transfer of the allergen, commonly to the face and neck. Even components that were originally deemed nonsensitizing, such as the ubiquitous cyanoacrylate adhesive family, have been found to be allergenic. They do not, however, cross-react with methacrylates and acrylates. Alternative options for individuals with allergic contact dermatitis reactions to these ingredients can be avoidance of these procedures or use of products that are "3, 4, 5 free" in which the common allergens dibutyl phthalate, toluene, and formaldehyde are absent. In cases where strengthening of the nail is the sole purpose, nail wraps or preformed nails can be applied for non-cyanoacrylate-sensitive individuals.
Sasseville D. Acrylates in contact dermatitis. Dermatitis. 2012 Jan-Feb;23(1):6-16. doi: 10.1097/DER.0b013e31823d1b81. PMID: 22653063.
Abstract. Acrylates are plastic materials that are formed by the polymerization of monomers derived from acrylic or methacrylic acid. They have found numerous applications in paints, varnishes and adhesives, in the printing industry, in the medical and dental professions, and in artificial nails. Beginning in the 1950s, many reports of occupational and nonoccupational allergic contact dermatitis to (meth)acrylate monomers have been published. These molecules are strong irritants, and patch testing can induce active sensitization. When patch tested, acrylate-allergic patients often display multiple positive tests. These reactions may represent cross-reactions, or concomitant reactions due to the presence, in the products responsible for sensitization, of impurities not disclosed in material safety data sheets. (Meth)acrylates are volatile and unstable chemicals, as demonstrated by their rapid disappearance from commercially available patch test allergens when exposed to air for more than a few hours.
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Alizadehgharib S, Östberg AK, Dahlgren U. Effects of the methacrylate/acrylate monomers HEMA, TEGDMA, DEGDA, and EMA on the immune system. Clin Exp Dent Res. 2017 Nov 17;3(6):227-234. doi: 10.1002/cre2.93.
Abstract. Incomplete curing of dental fillings may lead to leakage of methacrylate/acrylate monomers, which may come in contact with different cells of the immune system in oral tissues. Very little is known about the different immunologic effects caused by these methacrylates/acrylates. The objective of the present study was to study if and how the methacrylate/acrylate monomers ethyl methacrylate (EMA) and diethylene glycol diacrylate (DEGDA) affect the immune system in vivo and in vitro in comparison to 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA). Human peripheral blood mononuclear cells were exposed to the different monomers (500 and 1000 μM) for 24 hr in vitro. BioPlex Pro™ assays were used for cytokine analysis. In vivo, BALB/c mice were immunized subcutaneously at the base of the tail with HEMA, TEGDMA, EMA, or DEGDA in combination with ovalbumin (OVA) in order to study adjuvant properties of the 4 monomers. Peripheral blood mononuclear cells exposed to DEGDA had viability less than 50% of the cells. A pattern was observed where the levels of most cytokines were elevated after exposure to HEMA or TEGDMA. Since that, many cells died after DEGDA-exposure, the only observed cytokine secretion was a significantly increased production of interleukin-18. In the in vivo experiments, all mice immunized with DEGDA died after the booster injection. Mice receiving OVA in combination with HEMA, TEGDMA, or EMA developed a higher immunoglobulin G anti-OVA antibody levels compared to the group immunized with OVA alone. We could not demonstrate any significant difference in antibody levels among the mice receiving the various methacrylate/acrylate monomers. The different monomers affected the production, increase and decrease, of different cytokines in vitro but resulted also in vivo in increased antibody production and T-cell activity.
Koschitzki F, Wanka R, Sobota L, Gardner H, Hunsucker KZ, Swain GW, Rosenhahn A. Amphiphilic Zwitterionic Acrylate/Methacrylate Copolymers for Marine Fouling-Release Coatings. Langmuir. 2021 May 11;37(18):5591-5600. doi: 10.1021/acs.langmuir.1c00428.
Abstract. Methacrylate and acrylate monomers are popular building blocks for antifouling (AF) and fouling-release (FR) coatings to counteract marine biofouling. They are used in various combinations and often combined into amphiphilic materials. This study investigated the FR properties of amphiphilic ethylene glycol dicyclopentenyl ether acrylate (DCPEA) and the corresponding methacrylate (DCPEMA) blended with 5 wt % zwitterionic carboxybetaine acrylate (CBA) and the corresponding methacrylate (CBMA). A series of (co)polymers with different acrylate/methacrylate compositions were synthesized and tested against the attachment of the diatom Navicula perminuta and in short-term dynamic field exposure experiments. The more hydrophobic methacrylate DCPEMA homopolymer outperformed its acrylate counterpart DCPEA. Incorporated zwitterionic functionality of both CBMA and CBA imparted ultralow fouling capability in the amphiphilic polymers toward diatom attachment, whereas in the real ocean environment, only the employment of CBMA reduced marine biofouling. Moreover, it was observed that CBA-containing coatings showed different surface morphologies and roughnesses compared to the CBMA analogues. Particularly, a high impact was found when acrylic CBA was mixed with methacrylic DCPEMA. While the wettability of the coatings was comparable, investigated methacrylates in general exhibited superior fouling resistance compared to the acrylates.
