TP initiators

Figure 3.65. Mechanism of radical polymerization of an acrylate after excitation of a TP initiator.

One can easily see that polymer formation, as shown by the rod-like structures, depends on both parameters. There is still a need for methods allowing quantification of processes occurring in the focal volume of a TP initiated process. 

TP initiated cationic photopolymerization is an additional research target in TP photosciences [225]. The crosslinking of higher functional epoxies benefits from the lower shrinkage in comparison with acrylates [269]. In particular, those TP active systems with the capability to transfer an electron according to route A in... 

The use of TP initiated polymerization for 3D microfabrication has several advantages over OP initiated polymerization. A 3D resolution can be achieved with lateral and depth resolutions of 0.2 pm and 0.28 pm. This is fabrication at a... 

Figure 3.71. Optical system used for 3D microfabrication using TP initiated polymerization of a photopolymerizable composition. The numerical aperture of the objective lens is 0.85 (magnification of 40), the accuracy of the galvano-scanner set and the dc motor scanner were 0.3 and 0.5 pm, the beam power at peak in the photocrosslinkahle composition is about 3 kW, with a repetition rate of 76 MHz and a pulse width of 130 fs at a wavelength of 770 nm [76].

Figure 3.72. Dependence of lateral resolution and depth resolution on average power of a mode-locked Ti sapphire laser (wavelength 763 nm, 82MHz repetition, 130 fs pulse width) during TP initiated polymerization of a urethane acrylate resin. (From Ref. [575] with permission of SPIE—The International Society for Optical Engineering.)...

Figure 3.73. Volume size of voxels assuming ellipsoid structure as a function of the inverse of the scan speed. The voxels were obtained by TP initiated crosslinking radical polymerization of acrylates in the presence of poly (styrene-co-acrylonitrile) as binder and an amino-substituted distyrylbenzene as TP active initiator using a pulsed laser (150-fs pulses at a 76-MHz repetition rate or 85-fs pulses at a repetition rate of 82 MHz). (From Ref. [133] with permission of the Technical Association of Photopolymers, Japan.)...

Figure 3.74. Three-dimensional microstructures (photonic band-gap structure (a), magnified top view of the photonic band-gap material (b), tapered waveguide structure (c), cantilevers (d)) obtained by TP initiated polymerization. (From Ref. [134] with permission of Macmillan Magazines.)...

Figure 3.76. Voxels manufactured by TP initiated polymerization using different focusing height level (a) and scanning electronic microscopic images of the produced voxels (b). (From Ref. [580] with permission of the American Institute of Physics.)...

Figure 3.78. Scanning electron microscope images of a coin manufactured by TP initiated polymerization of tris(2-hydroxyethyl)isocyanurate triacrylate in the presence of poly(styrene-co-acrylonitrile) as binder and 167 as TP initiator using a frequency-doubled Nd YAG microlaser (0.5-ns pulses, 6.5-kHz repetition rate, wavelength 532 nm, average power 1.2 mW, 1.8-mm focal spot) (a) overview and (b) part of the coin with larger magnification. (From Ref. [136] with permission of the Optical Society of America.)...

A 3D optical memory device can be based on different principles. Among them are the write once and read many times principle, based on TP initiated photopolymerization resulting in a photopolymer structure [242] or photo-bleaching of a fluorescent material [250]. The rewritable principle is based mainly on TP induced molecular change. This TP induced molecular change can be an isomerization reaction in the writing process and OP induced fluorescence in the reading process [119, 144, 247, 258],... 

A photonic crystal-type stack of logs was obtained by TP initiated cross-linking radical polymerization of acrylates in the presence of poly(styrene-co-acrylonitrile) as binder and an amino substituted distyrylbenzene (58) as two-photon active initiator (Fig. 3.93) [133]. This photonic crystal-type microstructure has an average periodicity of 1 pm, a base area of 60 pm x 60 pm, and a height of 8 pm. The lines are about 200 nm wide, which is considerably smaller than the fabrication wavelength (Fig. 3.93) [133]. 

Figure 3.94. Waveguide structures manufactured by TP initiated polymerization of methyl methacrylate in the presence of a coumarin derivative and diphenyliodonium hexafluorophosphate as TP initiator using a 500-pW Ti sapphire femtosecond laser at 800 nm, equipped with a 0.65 NA microscope objective and a scanning speed of 40 pm/s. (a) Channel waveguide (2 pm), (b) T-shaped waveguide (signal input A signal output B probe signal C), and (c) directional coupler (coupling length is about 30 pm). (From Ref. [135] with permission of the Institute of Physics.)...

Toyota s former President Watanabe, interviewed by Stewart and Raman (2007), reaffirmed the two main pillars of the Toyota Way continuous improvement and respect for people which includes critical stakeholders, the employees, the supply partners and the customers. These operational and cultural tenets have been systemized within the Toyota Production System (TPS). Initially, TPS was conceived of as the "3P model of Purpose, Process and People. However, Liker (2004) refined and extended this to the"4P model of the Toyota Way, Philosophy, Processes, People and Partners, and Problem Solving, represented in Figure 4-1. 

---