Development of excimer lasers brought new phenomena for processing of polymer materials. Polymer ablation has already been utilized for micromachining in industry. In these years investigations on laser processing of polymer materials are extending to not only micromachining but also thin film preparation and surface modification. This paper reviews new techniques to prepare advanced polymer materials and discusses new directions of polymer processing.
Interaction of excimer lasers with polymer materials has induced various phenomena which could not be opened by other traditional methods or physical techniques. Most distinctive characteristics of excimer lasers is a source of high-quality and high-intensity ultraviolet photons, which makes possible to excite high electronic levels by multiphoton excitation mechanism. We can design and expect new reactions through higher excited levels for various starting materials including polymers. These possibilities will give useful processing of polymer materials if we correspond to industrial needs and design the most suitable reaction fields.

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The excimer laser ablation lithography(EAL) is a process of direct patterning and developing of a resist film by photo-decomposition ablation. Taking advantage of EAL process, we have tried to apply this process to LCD fabrication. As the most fundamental problem for resist materials is the ablation rate, we have examined to measure the ablation rates of many kinds of polymers. Among them the most promising is the polyurethane resin (PU) which is synthesized from toluenediisocyanate and poly(ethylene glycol) derivatives in chlorobenzene solution. The ablation rate at 100mJ/cm² fluence of 248nm is more than 0.05μm/shot, which is the highest value of all the materials that we have examined. Through the investigations of structures of PU, we could elucidate the mechanisms of the high ablation rate, and accordingly the molecular design concept of the ablation resist.

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Excimer laser ablation (ELA) of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA), 3, 4, 9, 10-perylenetetracarboxylic diimide (PTCDI), 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride (NTCDA) and perylene with 193(ArF), 248(KrF) and 308nm(XeCl) beams results in formation of amorphous semiconducting polymer thin films consisting of fine particles on several temperature-controlled substrates. The structure and electric conductivity of each prepared film depend considerably on the target material, ablation wavelength and substrate temperature. The films prepared on substrates at 300°C by ELA at 308nm from PTCDA and PTCDI partially contain polyperinaphthalene(PPN) structure with conductivity ranging from 10^-1to 10^-2Scm^-1.

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The curing of liquid photopolymer is determined by the exposure (optical energy) deposited. In laser stereolithography, laser exposure is considered as non-homogenous within the radiation area. In order to investigate the difference of the cure degree within the cross section of a single cured strand, a micro-structure was evaluated by hardness measurement. The hardness distribution was found to be not homogenous, the hardness reaches its peak at the center of laser beam on the photopolymer surface and is almost zero at the boundary of the liquid and solidified polymers. Further experiment shows that the hardness is linear to the laser exposure within a certain range. These results clarify that the theoretical derivation of laser exposure distribution is reliable.

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The new manufacturing technology called the rapid prototyping (RP) or layered manufacturing can fabricate very complicated solid objects fully automatically. RP industry is now growing quickly and new additive methods of manufacturing are coming along. Among many types of RP which have been put to practical use by this time, the system using liquid photopolymer and a laser beam is called "photo-shaping" or "stereolithography", and nowadays most popular. Here, the principle of it is first described. Then the newly proposed methods using liquid polymer are introduced. These aim to lower the cost or to enhance the ability of the systems. Finally characteristics of the resin necessary in the application of the solid models are pointed out.

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The thin films of semiconducting polymers such as poly(N-vinylcarbazole), polythiophene, polypyrrole, and polyaniline were formed by the laser chemical vapor deposition (CVD). The 355-nm laser excitation of N-vinylcarbazole deposited on a quartz substrate gave the poly(N-vinylcarba-zole) film with the molecular weight Mw=11860 (Mw/Mn=7.18). The sandwich excimer/second excimer emission ratio of the time-resolved emission spectra suggested the isotactic structure of the poly(N-vinylcarbazole) film prepared by the laser CVD. The micropatterns of the poly(N-vinylcarbazole) with the resolution of about 20μm were formed by the laser irradiation through a photomask. The laser flash photolysis of the N-vinylcarbazole showed the generation of the radical cation, which suggests the cationic polymerization mechanism. The optical band gap of polythiophene film was decreased with increasing laser excitation power.

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We present here our study on pulsed laser processings, particularly on molecular alignment, the change of microporosity and wettability of polymer and ceramic surfaces. Polarized pulsed laser-induced periodic surface structures (LIPSS) of sub-0.25μm size in a large area have been reported with polyimides, poly(ethylene terephthalate) and other polymer films using 4th harmonic Nd:YAG laser[1] and Ar-F excimer laser irradiation.[2] These LIPSS patterns were formed by repeated heating and cooling in polymer surfaces following intensity distribution caused by interference of reflected surface light and incoming polarized laser beam. Because of directional electric field of the polarized laser pulses, polymer functional groups align along the electric field in LIPSS image areas, as reported here for the first time using polarized reflected FT-IR. We also report the change of microporosity and wettability caused by pulsed laser using the fundamental, 2nd and 3rd harmonic irradiation of Nd:YAG laser. We extended our study to ceramic surfaces where electroless metal deposition induced by pulsed laser irradiation were carried out.

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The vapor-phase reaction induced by dielectric gas breakdown using a pulsed laser has been applied to the syntheses of the fine particles of Sn, Ti and V oxides. The phase characteristics and particle size were investigated using X-ray diffraction and transmission electron microscopy. Stannic oxide with a mean particle size of 8.2nm was synthesized from a gas mixture of SnCl₄+O₂. Titanium oxide (anatase: rutile=80:20) with a mean particle size of 8.5nm was synthesized from a gas mixture of TiCl₄+O₂. Rutile TiO₂ (rutile:anatase=91:9) with a mean particle size of 53nm was synthesized from a gas mixture of TiCl₄+O₂+H₂. Either VO₂ or V₂O₃ was formed from a gas mixture of VOCl₃+O₂+H₂ dependeding on the mixing ratio of the raw materials.

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We have developed a 473nm blue light generation source by frequency doubling using a KNbO₃ for intracavity second harmonic generation of a laser diode pumped Nd:YAG 946nm laser which is combined with an auto power control system and a temperature control for the entire resonator. We tried to stabilize the output power with the results that the fluctuation is less than ±1% at 15mW of blue light under a wide environmental temperature range of 0°C and 45°C.

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Novel liquid crystalline conducting polymers with photo-responsible function were synthesized by introducing an azobenzene moiety as a mesogenic core into side chain. Polymerizations of the liquid crystal-substituted acetylene monomer were carried out using a Rh-based or Fe-based catalyst. Observation of optical polarizing microscope demonstrated that the monomer exhibits a droplets texture characteristic of nematic phase, and the polymer a polygonal texture assignable to smectic phase. Reversible photochemical cis-trans isomerization of the azobenzene moiety as well as irreversible thermal isomerization from cis to trans form of the polymer backbone were elucidated.

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Photoconduction mechanism of an aliphatic polyimide, PI(PMDA/DCHM), and its sensitization by the addition of N, N, N′N′-tetramethyl-p-phenylenediamine(TMPD) were investigated by comparing them with those for an aliphatic polyimide containing two methyl substituents, PI(PMDA/DMDHM), and an aromatic polyimide, PI(PMDA/ODA). Photoconductivity of PI(PMDA/DCHM) would be the result of the weak intermolecular interaction formed by mixed layer packing arrangement between pyromellitic moiety of one polymer backbone and N-cyclohexyl ring of another one in the ground state. The irradiation of this weak intermolecular interaction forms immediately a charge-transfer complex in the excited state, produces charge carriers of radical cation and anion, and would result in the photoconductivity in the bulk polyimide film.
The addition of the electron donor increases the photocurrent generation of polyimide films by about three orders of magnitude shifting to longer wavelength by forming intermolecular charge-transfer complex in the ground state of the polyimide films. The doped-aliphatic polyimide film shows a larger enhancement of photocurrent probably due to the existence of only intermolecular charge-transfer complex in the polyimide film, compared to the case of the aromatic polyimide having charge-transfer complex both intra- and intermolecularly.

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We studied surface pressure-molecular area (π-A) isotherms for newly synthesized fullerene derivatives containing fluoroalkyl-chains ((CF₂)_nCF₃, n=3, 5, 7, and 9), and for their mixtures with arachidic acid at molarratio 1:5.5 and 1:9.75 and transferredfloating films onto a glass substrate. The limiting areas obtained from π-A isotherms for all compounds were larger than that of pure fullerene. These results indicated that fluoroalkyl- chains efficiently reduced the aggregation of fullerenes. There seemed an optimum length of fluoroalkyl- chains. The transferratio was not so high for pure fullerene derivatives, It was greatly improved for mixtures to more than 0.9, andY-type LB films were obtained.

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Nitrogen analogues of benzo[1, 2, 3-kl : 4, 5, 6-k′l′]dixanathene with 2-pyridyl group were synthesized from 1, 5-dichloroanthraquinone in six steps. After quaternization with iodoalkane, photochromic properties were investigated in ethanol or in toluene. The compound having a decyl group formed monolayer on water surface at 10°C.

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At present the biodegradable polyesters such as polycaprolactone are expected to be utilizable for preventing the environmental pollution due to plastics waste. The aliphatic polyesters are truly biodegradable in soils, but they are also photodegradable. Molecular weight of polylactic acid decreases to the half value by 1h UV irradiation. The mainchain scission occurs via the Norrish II type photo cleavage. Polycaprolactone is also well photodegraded. From these results, the aliphatic polyesters are concluded to be utilizable for a photodegradable polymer.

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We have designed and synthesized diphenylether diazonium salts as red color formers for a black-red dual color direct thermal recording system. The diphenylether diazonium salts obtained form red color via a coupling reaction with Naphthol-AS or yellow color via a coupling reaction with Naphthol-ASI4G. The color forming abilities of papers coated with the mixture of coupler, organic base, thermo-sensitizer and microcapsule incorporating the derivatives were examined. The derivative having normal butyl chain could be encapsulated in high amounts and formed vivid red color. Combined with another black color-forming diazonium salt, black-red dual color direct thermal recording was achieved.

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By going through the design and the synthesis of lots of phenol resins, the comparison of properties of the resins used in positive resists, also by learning previous work of others, the main factors influencing properties of binder resin of positive resist are proved:
1. The ratio of the total mass of phenolic resin (M) to the total mass of phenolic hydroxyl group of phenolic resin(A), namely the M/A value.
2. The magnitude of molecular weight of phenolic resin and the molecular weight distribution.
3. The condensation-polymerization ratio or the addition ratio of phenolic resin in double ortho way, namely o, o-bond ratio(Roo).
We found that there is correlation among the three factors to some extend, then we propose an empirical equation on the design of binder resin.

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The Fridel-Crafts reaction between dvinyl benzene (DVB) and resorcin produced a new type of photopolymer. When resorcin-DVB resins used in negative photoresists, 2um resolution can be reached [1]. When resorcin-DVB resins used as binder resins of PS plate and positive photoresists, they can fit with many kinds of photoactive compounds (PAC). The resolution of the positive resists can be lower than 0.95um. The exposure and developing rates of the positive photoresists are fast and they have good alkali resistance. Resorcin-DVB resins can be used as the ballast resins of diazonaphthoquinone (DNQ) group to synthesize DNQ-PAC. The positive photoresists whose PAC are resorcin-DVB diazonaphthoquinone have high resolution and the forming image has high contrast. During research, we also found that the alkali resistance of binder resin is closely relevant to the M/A value of the resin and the alkali resistance of PAC is closely relevant to the M/A value of the ballast resin.

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We developed a new positive working photosensitive polymer for semiconductor surface coating. Base resins were considered three kinds of heat-resistance polymers and we found that polybenzoxazole precursors(PBO) with photosensitizer diazonaphtoquinones and silicone modified polyamic acids added as adhesion promoters showed excellent patterning properties and film properties. Cured film of this photosensitive PBO also has not only low water absorption and low dielectric constant, but also high adhesion to substrates such as SiO₂, Si₃N₄ and molding compounds. The evaluation results of reliability made for this photosensitive PBO on testing elements was the same as that for existing non-photosensitive polyimides; it was found that the photosensitive PBO was on a practical level.

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The influence of aromatic tertiary amine (ATA) on the rate of photopolymerization (Rp) was studied in the MMA/BIP (benzoin isopropyl ether) system to improve the photoinitiation activity and anti-oxygen power of the benzoin alkyl ether initiators by using an auto-expander.

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The photochemical properties of a series of xanthene dye bis(diphenyliodonium) salts (XT(JPh₂)₂) were compared. The results of fluorescence quenching demonstrate that the electron transfer of XT(Iph₂)₂ is mainly from ion pair and the quenching rate constants approach 10^11-12M^-1s^-1 that is well above the rate limit controlled by diffusion. Effects of halogen substituents in the ortho positions adjacent to phenoxyl group in xanthene moiety directly affect their photoreactivities and dark storage stabilities. XT(Iph₂)₂ salts were applicable for vinyl monomers and the efficiency of polymerization depends on the rate of photogeneration of active radicals. Effects of solvent polarity and concentration of XT(Iph₂)₂ were also investigated.

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Three kinds of photopolymerizable polyfunctional polyesters were synthesized by polyesterification of polycarboxylic acid anhydride and polyols, modified with glycidyl methacrylate and then esterified by acetic anhydride. The modified dendritic polyesters contain a maximum of 6, 8 and 12 methacryl groups with approximately 2 of polydispersity, respectively. The dynamic viscosity measured using a spinning viscometer was compared with conventional linear epoxy (meth)acrylate oligomers with lower molecular weight, and it was shown that the viscosity of polyfunctional methacrylated polyesters is only half of that for the linear oligomers but the UV cure speed is about five times of that for the latter.

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The long-wavelength sensitive photoinitiating system composed of 3-n-propylsulfonic acid -2-[5-(3-n-propylsulfonic acid triethylamine-2-benzothiazolinylidene)-1, 3-pentadienyl]-benzoxazolium inner salt (SP-36), 2-chlorohexaarylbiimidazole (o-cl-HABI) and 3-mercapto-4-methyl-4H-1, 2, 4, -triazole(MTA), which acted as sensitizer, initiator and hydrogen-donor respectively, can be used to initiate the polymerization of methyl methacrylate (MMA). The kinetic study was carried out in trichloromathane solution at 30°C by using dilatometer. The relation between the polymerization rate and the concentrations of SP-36, o-cl-HABI, MTA and MMA was studied. The kinetic formula was deduced:Rp=K[SP-36]_0.45[HABI]_0.40[MTA]_0.24[MMA]_1.0. The photopolymer system can record stable hologram under Helium neon laser.

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The effect of crystallization temperature on the Crystallinity, melting point, and heat of fusion of photocross-linked high-density (HDPE) and low-density (LDPE) polyethylenes (XLPE) have been studied by using wide-angle X-ray diffractomer (WAXD), differential scanning calorimetry (DSC), and gel determinations. The WAXD measurements show that the crystallinity of polyethylene decreases with increasing irradiation time in the XLPE samples. However, comparing with photocross-linking the crystallization temperature has a crucial influence on the degree of crystallinity. The DSC data confirm that photocross-linking and different crystallization temperatures affect the regularity or size of crystals, which causes depression of the melting point (Tm) and decreases the heat of fusion.

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The image system consists of complex monomer of acrylic acid series, highly efficient sensitive to red light initiator, complex increasing sensitivity dye, it belongs to new type of phase holographic recording material of photopolymer. It is characterized by being sensitive to red light, high diffraction efficiency (>90%), high resolving power (>4000 lp/mm), high sensitivity (-1-2mj/cm²), operation under day light, storage under natural conditions in room over one year. It is suitable to make phase holographic optical elements and holograms.

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