Photopolymerization 2-hydroxyethyl methacrylate

The Effects of Initiator and Diluent on the Photopolymerization of 2-Hydroxyethyl Methacrylate and on Properties of Hydrogels Obtained... 

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,... 

In this work, the kinetics of these reactions are closely examined by monitoring photopolymerizations initiated by a two-component system consisting of a conventional photoinitiator, such as 2,2-dimethoxy-2-phenyl acetophenone (DMPA) and TED. By examining the polymerization kinetics in detail, further understanding of the complex initiation and termination reactions can be achieved. The monomers discussed in this manuscript are 2-hydroxyethyl methacrylate (HEMA), which forms a linear polymer upon polymerization, and diethylene glycol dimethacrylate (DEGDMA), which forms a crosslinked network upon polymerization. 

Photopolymerization with 2-hydroxyethyl methacrylate was then used to prepare the crosslinked copolymer. 

Di-block copolymers may also be formed by using dithiocarbamate free radicals. Indeed, copoljoners containing poly(styrene) and poly(hydroxyethyl methacrylate) blocks have been obtained by a two-step procedure [145]. Firstly, styrene is photopolymerized in the presence of benzyl A,A-diethyldithiocarbamate (BDC) by a living radical mechanism [146]. In fact, as the benzyl and thiyl radicals, formed by the photoliagmentation of BDC, participate mainly in the initiation and termination reactions respectively, polystyrene with a dithiocarbamate end group is thus obtained. The successive UV irradiation of this polymer, in the presence of hydroxyethyl methacrylate (HEMA), gives rise to the di-block copolymer, according to Scheme 42. 

Using a QCM, Josse et al. [27] have determined the storage and loss modulus of a commercially available UV-curable epoxy resin (SU-8-2002). An in-line monitor of the UV photopolymerization of 2-hydroxyethyl methacrylate with a photoinitiator of 1-chloroanthraquinone was demonstrated by Kim et al. [39]. 

More recently, iodonium salts have been widely used as photoinitiators in the polymerization studies of various monomeric precursors, such as copolymerization of butyl vinyl ether and methyl methacrylate by combination of radical and radical promoted cationic mechanisms [22], thermal and photopolymerization of divinyl ethers [23], photopolymerization of vinyl ether networks using an iodonium initiator [24,25], dual photo- and thermally-initiated cationic polymerization of epoxy monomers [26], preparation and properties of elastomers based on a cycloaliphatic diepoxide and poly(tetrahydrofuran) [27], photoinduced crosslinking of divinyl ethers [28], cationic photopolymerization of l,2-epoxy-6-(9-carbazolyl)-4-oxahexane [29], preparation of interpenetrating polymer network hydrogels based on 2-hydroxyethyl methacrylate and N-vinyl-2-pyrrolidone [30], photopolymerization of unsaturated cyclic ethers [31] and many other works. 

Under the assumption of bimolecular termination, the reaction diffusion parameter R (equation (4.2)) was determined for the bulk photopolymerization of multifunctional (meth)acrylates [I, 3, 6, 17, 481. It was found that for methacrylates at the plateau level, R was in the order of 2 1 moP [6] and for acrylates R was 3-5 1 moP [I7J. In general, reduction of network cross-linking density by co-polymerization with a difunctional reactive diluent (2-hydroxyethyl methacrylate (HEMA), octyl methacrylate) [3] increased the values of R due to increased mobility of the polymerization system until a plateau is reached. The addition of an inert diluent (polyethylene glycol 400 (PEG 400) [3, 6] or hydrogenated monomers [25. 53]) to a flexible monomer of low viscosity did not change R,... 

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...

Fig. 8. Raman spectra for photopolymerization of 2-hydroxyethyl methacrylate initiated with 2 mmolal dimethoxyphenylacetophenone at 50°C and light intensity of 75 mW/cm Raman spectra of the monomer and its polymer (left) and degree of monomer conversion based on monitoring the C=C bond depletion at 1640 cm (in this system, the internal reference band at 605 cm is constant throughout the reaction and cancels out in the conversion ratio) (right).

These semi-IPNs were synthesized [169] by the sequential method the PU network was synthesized (Sect. 2.3) and then swollen with 2-hydroxyethyl methacrylate (HEMA) monomer followed by its photopolymerization. The PHEMA content in these semi-IPNs varied from 10 to 57 wt%. 

Gam-Derouich, S., A. Lamouri, C. Redeuilh, R Decorse, F. Maurel, B. Carbonnier, S. Beyazit, G. Yilmaz, Y. Yagd, and M. M. Chehimi. Diazonium salt-derived 4-(dimethyl-amino)phenyl groups as hydrogen donors in surface-confined radical photopolymerization for bioactive poly(2-hydroxyethyl methacrylate) grafts. Langmuir 2012 8035-8045. 

Indeed, photopolymerization of acrylamide in aqueous solution on cell-GEHMP gives cellulose with the surface covered by a poly acrylamide) gel. Similarly, UV initiated polymerization of 2-hydroxyethyl acrylate, 2-(dimethylamino) ethyl methacrylate and A -vinylpyrrolidone carried out with the above functionalized Si(>2 results in the formation of a surfece polymer coating. 

Poly(amino acdd)-based NPs of 250 nm diameter with different surface PEGylations were prepared by photopolymerization of a,p-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEAS) and PEG-modified PHEAS (PHEAS-PEG) functionalized with a methacrylate group in inverse miaoemulsion. ... 

The receptor molecules and anionic sites containing photopolymerizable side groups were incorporated in the polysiloxane membrane. Covalent attachment of polysiloxane to the polyHEMA layer was achieved by prior methacrylation of part of the hydroxyethyl groups of polyHEMA. Subsequent photopolymerization yields a stable polymer network in which... 

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