2-hydroxyethyl methacrylate polymerization rate

Even the earliest reports discuss the use of components such as polymer syrups bearing carboxylic acid functionality as a minor component to improve adhesion [21]. Later, methacrylic acid was specifically added to adhesive compositions to increase the rate of cure [22]. Maleic acid (or dibasic acids capable of cyclic tautomerism) have also been reported to increase both cure rate and bond strength [23]. Maleic acid has also been reported to improve adhesion to polymeric substrates such as Nylon and epoxies [24]. Adducts of 2-hydroxyethyl methacrylate and various anhydrides (such as phthalic) have also been reported as acid-bearing monomers [25]. Organic acids have a specific role in the cure of some blocked organoboranes, as will be discussed later. 

A variety of photo-initiators and water-soluble diluents were used to study the photopolymerization of 2-hydroxyethyl methacrylate (HEMA). The rate of polymerization can be correlated to the structures as well as the concentration of initiators and diluents. It was found that, in terms of rate of polymerization,... 

Fig. 1. Viscosity change of supercooled monomers as a function of temperature. Monomer HEMA (2-hydroxyethyl methacrylate). GMA (glycidyl methacrylate). Te glass transition temperature. Ts temperature of maximum polymerization rate...

Fourier transform infrared spectroscopy glycidyl methacrylate group transfer polymerization 2-hydroxyethyl methacrylate hydrophobic-lipophilic-balance hydroxypropylcellulose 2-hydroxypropyl methacrylate initiator concentration decomposition rate constant propagation rate constant termination rate constant... 

Fig. 22. Monomer concentration dependence in various solvents of the rate of polymerization of 2-hydroxyethyl methacrylate (HEMA) by plasma (O, , ) and UV (A) exposure [176]. Plasma 100 W, s postpdymerization. 25 °C. UV 400 W mercury lamp in-source polymerization, 25 °C. Solvent G. A, water , ethand 03, DMSO...

Polymeric soft contact lenses came into existence in the 1950s (12]. Otto Wich-terle discovered the hydrogel poly(hydroxyethyl methacrylate) (HEMA), a transparent, soft, hydrophilic material that could be used to prepare contact lenses, Wichterle utilized a free radical polymerization of the HEMA monomer (including cross-linker, solvent, initiator, and stabilizer) with either thermal or ultraviolet initiation of the reaction. Initially, the len.ses were produced via spin casting, which involved the use of a concave mold that is spun at a particular rate. The rate of the mold spin determines the resultant lens power (13). After production of the lens in the mold, the lens would be hydrated from the mold in a warm water solution. Once hydrated, the lens would float free from the mold. Each lens is inspected for rips, tears, and clarity. Finally, the lens is packaged, sterilized, and boxed for shipping. The surface quality of the mold determines the surface chemistry and morphology on the anterior surface of the lens produced. 

Fig. 7. PhotodifFerential scanning calorimetry profiles for photopolymerization of 2-hydroxyethyl methacrylate initiated with 2 mmolal dimethoxyphenylacetophenone at 50°C and light intensity of 60 mW/cm with nitrogen purge polymerization rate (left) and degree...

In our own laboratory, we have developed a polymeric system which releases predictable small amounts of fluoride ions (up to 1 milligram per day) at a constant and controllable rate for a period of at least three months. To accomplish this, a Hawley orthodontic appliance was fabricated from poly(methyl methacrylate) beads and sodium fluoride dispersed in a monomer consisting of 2-hydroxyethyl methacrylate and methyl methacrylate. This composite was coated with a rate controlling membrane of poly(methyl methacrylate) with variable amounts of a hydrophilic monomer. The resulting system released fluoride ions over a 100 day period in a linear manner at rates up to approximately 2.0 mg/cm per day (30). The rate was a function of membrane thickness and the degree of hydrophilic monomer contained therein. 

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