Tetraethyleneglycol Diacrylate Research Articles

Thermal decay of trapped radicals produced during the photopolymerization of diacrylates

Direct evidence of the presence of extremely long-lived radicals produced in the photopolymerization of 1,6-hexanediol diacrylate and tetraethyleneglycol diacrylate has been obtained by EPR spectroscopy. As radical decay in thermal after-treatment is accompanied by additional polymerization and cross-linking, kinetic studies were carried out at different temperatures (40–120 °C) both by EPR spectroscopy and by analysis of the parallel disappearance of double bonds. Apart from EPR data at 120 °C, all experimental results show that both radical decay and double-bond conversion are first-order reactions, and kinetic constants evaluated for the two processes are practically coincident at the same temperature. Activation parameters for thermal after-treatment of the two diacrylates are almost the same, owing to the similarity in their chain length and mobility. The behaviour of the system at 120 °C, accounted for by a multiple relaxation model, is interpreted as being due to prevailing cross-linking reactions in the vitrified network of trapped radicals.

Thermal and mechanical analysis of a photopolymerization process

Network formation by photopolymerization has been studied for tetra-ethyleneglycol diacrylate (TEGDA) using isothermal differential scanning calorimetry (d.s.c.) and dynamic mechanical thermal analysis (d.m.t.a.). Owing to vitrification, the polymerization does not go to completion at room temperature. The ultimate conversion as measured by d.s.c. seems to depend on light intensity. This effect is not caused by self-heating. In thin layers as used with d.s.c. the temperature rise is less than 3 K. However, mechanical measurements show that especially at low intensities the photopolymerization process continues for a considerable time at a rate which cannot be detected by d.s.c. At equal doses the temperatures of maximum mechanical loss, T(tan δ max), were observed to be the same. D.m.t.a. of partially polymerized samples of TEGDA reveals an increase of Young's modulus due to thermal postcure near 120°C. Parallel d.s.c.-extraction experiments show that this aftercure requires the presence of free monomer. Near the end of the polymerization the free monomer is exhausted and only crosslinks are formed. T(tan δ max) then increases markedly with double-bond conversion. Trapped poly(TEGDA) radicals decay in the dark with the formation of radicals with a single-line electron spin resonance spectrum, presumably due to CH 2CH 2O∗ radicals. After 21 h most of the radicals have disappeared.

Photosynthetic membranes II: Kinetic studies of photoinitiated grafting of some acrylic monomers onto cellulose

Photochemical grafting of 1,6-hexanediol diacrylate, diethylene glycol diacrylate and tetraethylene glycol diacrylate onto cellulose in the form of filter paper was investigated kinetically at 30 ± 2 °C with 1,2-diphenyl-2,2-dimethoxyethanone as a photoinitiator, under experimental conditions suitable for the preparation of membrane systems. Irradiations were carried out polychromatically, with incident radiation of flux (2.5 × 10 −8)−(22.6 × 10 −8) einsteins s −1 cm −2. The ratio R between the molar concentrations of photoinitiator and monomer were varied between 0.005 and 0.095, while the n/S value ( n, moles of diacrylate monomer deposited per unit apparent surface S) was varied between 7.61 and 75.0 μmol cm −2. Two consecutive constant-rate processes were indicated by the kinetic curves. The quantum yields Φ 1 and Φ 2 for the first and second constant-rate periods were calculated. They are almost insensitive to the difference in diacrylate monomer structure; the Φ 1 show a linear dependence on R, while the Φ 2 show an inverse dependence on n/S. The relevance of photochemical parameters in the proposed reaction mechanism is discussed.

Continuous enzyme reactions with immobilized enzyme tubes prepared by radiation cast-polymerization

Immobilized glucose oxidase tubes were prepared by radiation cast-polymerization of 2-hydroxyethyl methacrylate and tetraethyleneglycol diacrylate monomer at low temperatures. The immobilized enzyme tubes which were spirally set in a water bath were used as reactor, in which the enzyme activity varied with tube size and flow rate of the substrate. The conversion yield of the substrate in continuous enzyme reaction was about 80%.

Properties of UV‐curable polyurethane acrylates: Effect of reactive diluent

AbstractSeveral families of UV‐cured polyurethane acrylates were synthesized, and the effects of reactive diluent type and content on their physical properties were investigated. Increasing reactive diluent content promoted the development of a second, high glass transition temperature phase in all the materials, thereby leading to increased strength and modulus. Changes in the extensibility of the samples upon addition of reactive diluent were inversely related to the effect of the diluent on the crosslink density. The effects of using different reactive diluents (di‐, tri‐, and tetraethylene glycol diacrylate and N‐vinyl pyrrolidone) on the physical properties of the samples were attributed to differences in the softening point (Tg) of the homopolymer reactive diluents and the relative compatibility of the reactive diluents with the urethane acrylate segments.

Preparation of immobilized enzyme surfaces by radiation technique

Immobilized cellulase surfaces were prepared by a simple radiation technique, coating 2-hydroxyethyl methacrylate and tetraethyleneglycol diacrylate on the inner surface of a polyethylene tube. The durability of the surfaces was examined by repeated batch enzyme reactions as a function of monomer and enzyme concentration. The amount of the enzymes located on the surface was about 0.5 mg/cm 2, in which the enzymes did not leak from the polymer matrix. The optimum monomer concentration in the immobilization was 60–70%.

Encapsulation of enzymes by radiation technique

A new preparative technique for the encapsulation of enzymes by radiation polymerization was studied using cellulase, 2-hydroxyethyl methacrylate, and tetraethylene-glycol diacrylate. The enzyme activity of the immobilized enzyme capsules varied with the thickness of the membrane and with the size of the capsule; optimum size and thickness giving high enzyme activity were 0.5 – 2 mm and 50 – 200 μm, respectively. The durability of the capsules was examined by continmuous enzyme reaction.

Immobilization of enzymes by radiation

Immobilization of various enzymes was performed by radiation-induced polymerization of glass-forming monomers at low temperatures. α-Amylase and glucoamylase were effectively immobilized in hydrophilic polymer carrier such as poly(2-hydroxyethyl methacrylate) and also in rather hydrophobic carrier such as poly(tetraethyleneglycol diacrylate). Immobilized human hemoglobin underwent the reversible oxygenation concomitantly with change of oxygen concentration outside of the matrices.

Casting of organic glass by radiation-induced polymerization of glass-forming monomers at low temperatures. IV. Casting and polymer properties of monomeric systems including polyfunctional monomers

The applicability to radiation-induced cast polymerization of polyfunctional monomers or systems including them was studied. Most of polyfunctional monomers could be glassified and were applicable to radiation casting. The effect of tetraethylene glycol diacrylate on inner-plasticized comonomer systems was studied in detail. It was found that the glass-forming property increased by the addition of tetraethylene glycol diacrylate and that heat durability improved satisfactorily. The formation of optical strain in casting was relatively easier in polyfunctional monomers including systems due to inner stress, although the merit of radiation casting was still obvious.