P.2 Biocompatible and biodegradable monomers based on oligoethylene glycols with different polymerizable groups
(Session: New Synthesis Routes, Chemistries and Structures)
Prof. Robert Liska, University of Technology, Vienna, Austria

Polyethylene glycol (meth)acrylates are frequently used for the assembly of biodegradable materials via photopolymerization techniques. Beside the considerable irradiancy and sometimes toxicity of acrylate-monomers, the formation of polyacrylic acid through hydrolytic degradation of the polymer is another undesirable aspect of these materials when applied in the biomedical field. Besides a local decrease of the pH value, calcium ions are able to cross-link the polymer chains and therefore excretion is not possible. Therefore, oligoethylene glycols were endcapped with alternative polymerizable groups (vinylesters, vinylcarbonates and vinylcarbamates) to form non-toxic polyvinyl alcohol-based polymers during photocuring. Photoreactivity, cytotoxicity, mechanical properties and degradation characteristics of these new materials were studied and compared to the corresponding (meth)acrylates.

P.3 Photo-induced waveguide formation in polysiloxanes
(Session: New Synthesis Routes, Chemistries and Structures)
Prof. Robert Liska, University of Technology, Vienna, Austria

The aim of this work was the development of materials for writing optical waveguides into flexible polydimethylsiloxane (PDMS) layers by means of laser structuring techniques. An important application would be the connection of optical components on flexible circuit boards in the communication technology. Well known techniques from the literature are based on the concept of photolocking. To avoid the additional step of swelling the low refractive PDMS matrix with the photocurable monomer, we present two concepts wherein curing of the PDMS matrix is possible in the presence of a variety of new monomers. Classical radical polymerization and cationic ring opening polymerization were employed with a set of high refractive monomers that meet the high requirements of optical interconnects. Optical waveguides were successfully written into the silicone-monomer hybrid materials both by µ-stereolithography and 2-photon polymerization.

P.4 Glass-particle-covered transparent sheets with UV curable coatings for high quality floor-use ink jet media and various kinds of flooring
(Session: Application Properties)
Mr. Nobuo Yamamura, GEN Maintenance Technology Inc., Japan

UV curable coatings with fine glass particles are coated on thin PET sheets. The coatings consist of oligomers of more than 6 functional groups, which were presented at RadTech Asia '03 titled 'UV Curable Water-bone Floor Polish, "WINUP."' The fine glass particles are transparent and retroreflective and the diameters are under 0.03mm. Without monomers or oligomers of low functional groups, the coated sheets can offer long-lasting high gloss and unblemished surface even under heavy-walking conditions. Moreover, weathering resistance properties are added to the coatings. With the fine glass particles, the sheets can be applied in the open air for their no-slippery properties even in the rain. Thin PET sheets can be applied because of fine glass particles having the shrinkage reduction effects at the UV curing process. It is the extra benefit of using fine glass particles.

P.5 Curing Kinetics and Property of Korean Dendropanax (Golden Varnish) Formulated with radiation curable resins.
(Session: Application Properties)
Mr. Hyeon-Deuk Hwang, Seoul National University, South Korea

The Korean Dendropanax is made from a natural resinous sap and has used as a golden and transparent varnish for the traditional artifacts to make them brilliant golden colored. The cured film has excellent protective properties such as weatherability, water resistance, and anticorrosive. The Korean Dendropanax has conjugated diyne compounds as the radiation curable materials. So we intended to accelerate the curing rate by dual curing of thermal and radiation curing with adding a thermal initiator and a photoinitiator. Also the curing behavior and properties of the Korean Dendropanax, formulated with radiation curable resins, were investigated. Radiation curing be-havior was analyzed with photo-DSC and FT-IR. And also, physical property and viscoleastic property were measured by a pendulum hardness tester and a rigid-body pendulum type tester (RPT), respectively. The curing rate and properties of the Korean Dendropanax were improved with formulating with radiation curable resins and through dual curing.

P.6 Viscoelastic properties and PSA performnaces of high-performanced acrylic PSAs
(Session: Adhesives)
Mr. Dong-Hyuk Lim, Seoul National University, South of Korea

For the next generation PSA(Pressure-Sensitive Adhesive), high performanced and environmental friendly PSA, the UV curing technology has become a well-accepted technology in adhesive and PSA technology. The UV curable PSA, one of the the fusion technology between UV curing and PSA, has been in the limelight recently. The viscoelstic approach to UV curable PSA was inactived. The relationship between PSA performances and viscoelastic properties has been researched due to effective control quaility of PSA products. In this study, we prepared photopolymerizable acrylic PSA with high perofrmances, and evaluated viscoelastic properties and PSA performances. The relationship between PSA performances and viscoelastic properties is very important.

P.7 3D fabrication of new poly(vinyl alcohol) based ccaffolds for tissue engineering
(Session: Advances in Photochemistry & Polymerisation)
Prof. Robert Liska, University of Technology, Vienna, Austria

The use of (meth)acrylate-based photopolymers as biomaterials has gained increasing interest recently because of their easy access, tailorable mechanical properties and their ability of being structured by rapid prototyping techniques. However, methacrylates suffer from poor photoreactivity and acrylates show high affinity to side-reactions with amines like proteins causing adverse effects in the human body, making them less suitable for tissue engineering applications and providing the need for other polymerizable groups. Therefore, new monomers based on vinyl esters, vinyl carbonates and vinyl carbamates were synthesized, which potentially result in water-soluble and biocompatible poly(vinyl alcohols) upon hydrolytic degradation. For basic investigations concerning the suitability of the new materials for biomedical applications, the photoreactivity and biocompatibility of the monomers as well as the mechanical properties and cytocompatibility on polymer specimens were tested. It could be observed that the new monomers were about two orders of magnitude less toxic compared to acrylates and their photoreactivity was between the ones of acrylates and methacrylates. Furthermore, similar mechanical properties compared to their (meth)acrylate references suggest making them suitable starting materials for several tissue engineering applications.

P.8 Reactivity of new photoinitiating systems under UV and visible light usable in FRP and FRPCP.
(Session: Advances in Photochemistry & Polymerisation)
Mr. Jacques Lalevee, Ecole Nationale Supérieure de Chimie de Mulhouse, France

Examples of new photoinitiators systems are provided: i) thiopyrylium and pyrylium salt/thiol/disulfide and silane combinations for visible light induced free radical polymerization (FRP) or free radical promoted cationic polymerization (FRPCP) under visible lights in laminate and aerated conditions as well and ii) amine and phosphine ligand containing borane complexes BC as highly efficient co-initiators for acrylate photopolymerization. The reaction mechanisms are investigated by laser flash photolysis, ESR and DFT calculations. The structure/reactivity trend is discussed. The photoinitiation step mechanism under air is presented.

P.9 New and highly efficient photoinitiating systems for free radical and free radical promoted cationic photopolymerization in aerated media
(Session: Advances in Photochemistry & Polymerisation)
Mr. Jacques Lalevee, Ecole Nationale Supérieure de Chimie de Mulhouse, France

Examples of recently investigated systems being able to work as co-initiators for free radical photopolymerization FRP or as a radical source for free radical promoted cationic polymerization FRPCP under air are presented. New systems for the UV and visible light induced polymerization are designed. They are based on a photoinitiator (e.g. benzophenone, camphorquinone, isopropylthioxanthone, Eosin) and a co-initiator such as silane, a germane, a thiol, a disulfide in FRP; a diphenyl iodonium salt is added in FRPCP. The overall efficiency is strongly affected by the co-initiator structure. The rates of polymerization and final percent conversion are noticeably higher than those obtained in the presence of already studied reference systems. An unusual enhancement of the polymerization kinetics is found in aerated conditions. The excited state processes and the role of oxygen as revealed by laser flash photolysis are discussed.

P.10 Investigation of processes in photoinitiating systems through ESR spin trapping and kinetic ESR.
(Session: Advances in Photochemistry & Polymerisation)
Mr. Jacques Lalevee, Ecole Nationale Supérieure de Chimie de Mulhouse, France

ESR Spin Trapping is a powerful technique for the characterization of radicals. This is exemplified here through the investigation of the cleavage processes in various photoinitiators PI such as a radical PI, a cationic PI, a photoacid, a photobase. The sensitized cleavage of selected compounds is also presented. The results show a difference of selectivity between the two used spin traps and outline their complementarities. Kinetic ESR is also a versatile technique to determine rate constants of slow radical reactions or/and of reactions where the radical species absorb in a spectral window hardly accessible by a laser flash photolysis: this will be applied to the reactions of peroxyl radicals.

P.11 Simultaneous analysis of the UV curing of acrylate-nanoparticle formulations by combined photorheometry and FT-NIR spectroscopy
(Session: Advances in Photochemistry & Polymerisation)
Dr. Tom Scherzer, Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Germany

In this contribution, we present a new high-performance analytical technique for the investigation of the kinetics of UV photopolymerization reactions which comprises photorheometry and Fourier transform near-infrared spectroscopy (FT-NIR). This method allows simultaneous and time-resolved monitoring of photopolymerization reactions with respect to both their conversion and viscoelastic properties (e.g. viscosity, shear modulus), i.e. the evolving rheological properties can be followed in dependence on the actual conversion within the chemical system. The technique was found to be a powerful tool for studying UV curing reactions in both industrial and academic research. In the present study, it was used to study the curing process of acrylate formulations which had been modified with nanoparticles. Their photopolymerization was followed in dependence of various parameters such as chemical type and concentration of nanoparticles and photoinitiator, irradiation dose, and temperature. The kinetic data were compared with conventional mechanical parameters such as microhardness, scratch hardness, abrasion resistance, etc.

P.12 Hemicyanine dyes of benzimidazole ring systems as effective photoinitiators in an argon laser induced TMPTA photopolymerization
(Session: Advances in Photochemistry & Polymerisation)
Dr. Beata Jêdrzejewska, University of Technology and Life Sciences, Poland

The key role in all photopolymerization processes plays the photoinitiating system, which after irradiation generates a reactive species initiating the polymerization chain of vinyl monomers. Our latest photopolymerization studies have shown that styrylbenzimidazolium n-butyltriphenylborate dyes exhibit high efficiency of photoinitiation. The redox pairs containing structurally related, dichromophoric styrylbenzimidazolium borates initiate the polymerization reaction with the efficiency comparable to Rose Bengal derivative (RBAX), common triplet state initiator. The mechanism for photoinitiation with hemicyanine-butyltriphenylborate complex involves butyl radical formation as a result of photoinduced electron transfer from a borate anion to the singlet excited state of the hemicyanine dye cation, followed by addition of an butyl radical formed to the carbon-carbon double bond of the acrylate. The relationship between the rate of polymerization and the free energy of activation of electron transfer reaction shows the dependence predicted by the classical theory of electron transfer phenomena.

P.13 N-methylpicolinium esters as the second co-initiators in three-component visible light photoinitiating systems for vinyl monomers polymerization
(Session: Advances in Photochemistry & Polymerisation)
Dr. Janina Kabatc, University of Technology and Life Sciences, Poland

Addition of N-methylpicolinium esters as a second co-initiator into cyanine borate salt photoinitiating system visibly increases the efficiency of polymerization photoinitiation. The cyanine dyes are able to start a specific chain of an electron transfer reaction involving different additives (borate salt and N-alkylpicolinium derivatives), giving as a result one photon - two-radicals photochemical response. The mechanism of free radical formation by dye/borate/N-methylpicolinium derivative system was constructed based on the laser flash photolysis measurements. The primary photochemical reaction involves an electron transfer from the n-butyltriphenylborate anion to the excited singlet state of the dye, followed by the reaction of the N-methylpicolinium derivative with the resulting dye radical to regenerate the original dye. This reaction simultaneously produces a N-methylpyridyl radical, which undergoes the carbon-oxygen bond cleavage yielding radicals active in initiation of free radical polymerization chain.

P.14 Oganic-inorganic photocured thiolene nanostructured coatings
(Session: Advances in Photochemistry & Polymerisation)
Ms. Colucci Giovanna, Politecnico de Torino, Italy

The aim of this work is to prepare hybrid silica-thiol-ene coatings, combining the photopolymerization process with the sol-gel chemistry reaction. The thiol-ene UV photocurable coatings are based on a mixture of an allyl and a multifunctional thiol that undergo a polyaddition reaction upon UV irradiation. These systems have an extensive list of advantages compared with the usual polymerization processes, such as low polymerization shrinkage, reduced oxygen inhibition, photoinitiatorless and high reactivity. On the other hand, they have low mechanical and surface properties due to the formation of thio-ether linkages. For this reason, dual cured thiol-ene coatings have been prepared with the purpose to overcome their mechanical, thermal and surface properties. TEM analyses have been also performed to investigate the morphology of silica domains generated in the photocured networks.

P.15 Investigation of the exothermicity of radical induced photopolymerization by RTFTIR spectroscopy and photoDSC
(Session: Advances in Photochemistry & Polymerisation)
Prof. Dr. Céline Croutxé-Barghorn, Ecole Nationale Supérieure de Chimie de Mulhouse, France

Exothermicity of the radical photopolymerization of coatings were investigated for various acrylic monomers bearing different functionalities. The maximum conversion ratio and the rates of polymerization were monitored as a function of time by RT-FTIR spectroscopy and photo-DSC. The change in temperature due to the polymerization reaction was probed by using a polypropylene film as internal temperature probe and calorimetric measurements. Additionally, photo-DSC experiments were performed at three different temperatures corresponding to the rubbery plateau, glass transition region and glassy state of each polymer in order to evaluate the influence of the temperature substrate on the final polymer network. The corresponding glass transitions were determined by Modulated DSC. For some specific experimental conditions, a residual exothermicity was observed and attributed to the fast vitrification that takes place under UV curing. This study allows a general discussion on the effect of the temperature increase on the polymer network during radical induced photopolymerization.

P.16 Excited state processes in new families of radical photoinitiators
(Session: Advances in Photochemistry & Polymerisation)
Prof. Xavier Allonas, Ecole Nationale Supérieure de Chimie de Mulhouse, France

Barton esters, thiohydroxamic and hydroxamic esters and ethers have been proposed as new photoinitiators for radical photopolymerization. The excited state processes are investigated here by laser flash photolysis, ESR and molecular orbital calculations. Singlet or/and triplet cleavage occurs leading to the formation of various radicals. Typical reaction mechanisms are proposed.

P.17 Polymer-nanosilica composites prepared by in situ photopolymerization
(Session: Advances in Photochemistry & Polymerisation)
Dr. Maciej Andrzejewski, Poznan University of Technology, Poland

In the work the preparation and characterization of composite materials containing nanosilica, precipitated (spherical) and of the Aerosil type is presented. The silica was organically modified with 0, 5, 10 or 20 w/w of the modifier or was used without modification. The composites containing 0 - 30 wt.-% of silica were prepared by dispersion of the filler in meth(acrylate) monomers and photopolymerization of the resulting mixtures. The effect of the modification on physicochemical properties of the filler, curing kinetics and some properties of the composites were investigated.

P.18 Investigations on acylsilanes as photoinitiator for radical polymerization
(Session: Advances in Photochemistry & Polymerisation)
Ms. Astrid Gugg, University of Technology, Vienna, Austria

The state of the art photoinitiator system for dental filling materials consists of camphorquinone and ethyl 4-dimethylaminobenzoate. Unfortunately, they suffers from low reactivity, especially in water-based formulations. Bisacylphosphine oxides feature higher reactivity, but their absorption spectra do not overlap adequately with the emission spectra of the novel LED-based dental lamps (430 - 490 nm). Recently, we have presented acylgermanium compounds as excellent alternative. As the price of the precursor limits the field of application, we were interested in similar photoinitiators based on silicon. As there is only less known on the photoactivity of rather unstable acylsilanes, we have successfully prepared a series of new compounds. The implementation of different sterically demanding substituents resulted in the stabilisation of the system while some moderate reactivity was found. UV-VIS spectroscopy confirmed absorption behaviour similar to germanium-based compounds with maxima at 410-420 nm.

P.19 Photoinitiators with ß-phenylogous cleavage
(Session: Advances in Photochemistry & Polymerisation)
Ms. Claudia Dworak, University of Technology, Vienna, Austria

Very recently, we have demonstrated that phenyl glycine covalently bound to benzophenone has surprising photoinitiation ability for radical polymerization, although it seems to belong to classical Type II photoinitiators. Modification and optimization of this molecule failed and the type of linkage turned out to be a crucial point for the good performance of this molecule. Photoproducts of steady state photolysis experiments were characterized by HPLC and GC-MS indicating a ß-phenylogous cleavage, which seems to be responsible for the high activity. Furthermore CIDNP experiments and ESR measurements were carried out to get a deeper insight into the photochemistry of this initiator.

P.20 Hydroxylamine-based monomers
(Session: Advances in Photochemistry & Polymerisation)
Ms. Claudia Dworak, University of Technology, Vienna, Austria

The purpose of our studies was the design of a new class of acrylate-based monomers with an UV cleavable heteroatom bond, offering the possibility to initiate radical polymerization upon irradiation with UV-light. An accurate method to derive the double bond conversion from the ATR-IR spectra of the monomers and the cured polymers was employed, that enabled us to calculate the theoretical polymerization heats of the new monomers. Their photopolymerization properties were determined by Photo-Differential Scanning Calorimetry. Surprisingly, some of these new monomers exhibited high self-initiation behavior, comparable to well established Type II photoinitiator systems like benzophenone / triethanolamine, although only a fraction of the light could be absorbed by this compounds.

P.21 Photopolymerizable waveguides in flexible sol-gel cladding materials
(Session: Innovations)
Prof. Robert Liska, University of Technology, Vienna, Austria

In this work, we investigated the application of porous and optical transparent carrier materials comprising inorganic-organic hybrid materials based on true liquid templating for waveguide structuring via two photon polymerisation. As such hybrid materials are often hard and brittle, we have introduced polyethylene glycol containing co-precursors to enhance the mechanical properties of the porous material. Dimension and size of porosity of the flexible films were confirmed by AFM. The carrier material was able to get infiltrated by a photocureable monomer of significantly higher refractive index. Finally we were successfully able to prove the principle to generate waveguide structures within the organic-inorganic carrier material.

P.22 Rapid prototyping of biocompatible and biodegradable monomers
(Session: Innovations)
Prof. Robert Liska, University of Technology, Vienna, Austria

Stereolithography is a very capable technology for the 3D-structuring of photocurable monomer formulations since high resolutions and complex geometries can be realized by this technique. Beside a high reactivity of the resin, the shrinkage and the mechanical properties of the final part material are another essential parameter. Low molecular monomers lead to densely cross-linked materials which suffer from high shrinkage and strains within the cured material. Therefore, we have prepared various high molecular weight monomers based on biocompatible and biodegradable oligomeric fatty acid and lactic acid derivatives with vinyl ester, vinyl carbonate and vinyl carbamate as photoreactive groups. For the cured materials, mechanical properties and degradation behaviour were studied. The possibility of 3D-structuring has been proven by microstereolithography giving cellular structures with feature resolutions lower than 25 µm.

P.23 Evaluation of triple bond containing photoinitiators for the two-photon induced photopolymerization process
(Session: Innovations)
Prof. Robert Liska, University of Technology, Vienna, Austria

Recently, the triple bond containing, Michler's ketone-based photoinitiator NDPD showed excellent results in two-photon induced photopolymerization. By using this real 3D rapid prototyping technique it is possible to produce sub-µm parts which could be used in mechanical, electronic and optical microdevices, high-density 3D optical data storage, photonic crystals, polymer-based optical waveguides on integrated circuit boards and the like. Herein, we present the synthesis and evaluation of a series of photoinitiators characterized by a cross conjugated D-?-A-?-D system based on NDPD. The influence of the chemical structure on the photoreactivity was investigated by variation of donor and acceptor functionalities and the conjugated backbone. Besides UV-Vis spectroscopy and fluorescence measurements, the photoinitiator activity and ideal structuring window for each initiator was evaluated by two-photon induced microfabrication. We were able to demonstrate that these new initiators show at least equal or better reactivity compared to two highly reactive two photon absorption initiators well known from literature to give shapes with a wall thickness of about 200 nm.

P.24 Studies on the mechanical behaviour of photoelastomers for vascular tissue regeneration.
(Session: Innovations)
Prof. Robert Liska, University of Technology, Vienna, Austria

The mechanical properties of materials designated for vascular tissue replacement are of crucial importance. The elastic modulus, the tensile strength as well as the suture tear resistance have to be optimized. Therefore, a commercially available urethanediacrylate was chosen as base monomer. The mechanical properties of the photoelastomers can be tailored by addition of a reactive diluents (2-hydroxyethyl acrylate) and thiols (3,6-dioxa-1,8-octane-dithiol) as chain transfer agents to comply with the mechanical properties of natural blood vessels. By means of microstereolithography (a rapid prototyping method) a cellular structure perfectly promoting the ingrowth of new tissue and the exchange of nutrients could be structured out of the optimized resin formulation. Cell culture experiments with endothelial cells confirmed the suitability of this formulation.