Poly-4-hydroxystyrene

PHOST represents poly(4-hydroxystyrene). The properties of the isomeric poly(2-hydroxystyrene) and poly(3-hydroxystyrenes) differ substantially (87). 

In another application, the diazonium salt (D1 or D2) (2.5 wt%) was dissolved in a mixture of cyclohexanone and acetic acid containing 12.5 wt% poly(4-hydroxystyrene) and 2. 5 wt% Methylone resin (GE 75108). The resist was exposed with a 600-W Xe-Hg lamp through a 313-nm interference filter. After exposure the resist was baked at 80V for 3 minutes and developed in a 1 wt% tetramethylammonium hydroxide aqueous solution. 

Figure 11. Exposure curve of the acid-catalyzed resist system consisting of poly(4-hydroxystyrene), D2, and...

UV spectra of both polymers IV and V taken from ca. ljim thick films showed that the each of the polymers had absorbencies of less than 0.30 per micron of film thickness at 254 nm as shown in Figure 6 for polymer V. This allows their use with triarylsulfonium salts, which generally absorb in the deep UV. In addition, it is known that poly(4-hydroxystyrene) does not absorb strongly in the deep UV, while poly(3,5-dimethyl-4-hydroxystyrene) also shows no strong absorption band near 254 nm (Figure 6). 

While this work has focused on certain allylic and benzylic ether derivatives of poly(4-hydroxystyrene) it is possible to extend the concept to the corresponding t-butoxy substituted polymers although the preparation of such polymers is relatively more difficult than in the present case. 

Poly(4-hydroxystyrene) [I], poly(4-hydroxy-3-methoxystyrene) [II], poly(4-hydroxy-3,5-dimethoxystyrene) [III] and their acetates were synthesized from 4-hydroxybenzaldehyde, vanillin and syringaldehyde (2), which were synthesized as shown in Scheme 1. 

Poly(4-hydroxystyrene) was previously prepared by the authors (2) by the decarboxylation of 4-hydroxycinnamic acid followed by the free radical polymerization using Vazo 67. 

The bottom antireflective coating solution test consisted of the step 1 product, poly(4-hydroxystyrene-9-anthracenyl-methacrylate) (1.5 g), 55/45 molar ratio, respectively, oxalic acid/triethylamine (0.075 g) 1 1, triphenylsulfonium triflate (0.06 g), and Vectomer 5015 (0.225 g) dissolved in ethyl lactate (98.5 g) and then filtered through... 

Westover et al. 95 prepared lightly crosslinked nitrated poly(4-hydroxystyrene) microspheres for pH sensors. The microspheres were produced using SPG membranes followed by suspension polymerization and they showed diameters between 1 and 2 micrometers. 

Tyrosinase catalyzes the oxidation of phenols. These enzymes are widespread in fungi, plants, and animals. Polyhydroxystyrene (PHS) is a phenol-containing polymer used as the excellent polymer matrix due to its good coating properties. Phenol moieties of PHS can be oxidized by tyrosinase. Mushroom tyrosinase was observed to catalyze the oxidation of 1-2% phenolic moieties of the synthetic polymer poly (4-hydroxystyrene) (PHS) (Shao et al., 1999) (Figure 4.5). 

Fig. 8 Illustration of a (3.4.6.4) Archimedian tiling self-assembled structure of a 2 1 blend of poly(2-vinylpyridine)-l>Zocfc-polyisoprene-l)Zocfc-poly(2-vinylpyridine) and polystyrene-fcZocfc-poly(4-hydroxystyrene). P denotes poly(2-vinylpyridine), H denotes poly(4-hydroxystyrene), S denotes polystyrene and I denotes polyisoprene. Reprinted with permission from [45]. 2006 American Chemical Society...

FIgyre 2.16 Variation of melting temperature with crystallization temperature for (O) poly(8-caprolactone) and ( ) poly(E-caprolactone) in a blend with poly(4-hydroxystyrene) (85% weight fraction of PCL). (From Ref. 15.)... 

One polymer from this class that has been studied by Py-GC/MS is poly(4-vinylphenol) or poly(4-hydroxystyrene), CAS 24979-70-2, with the idealized structure -[CH2CH(p-C6H40H)-]n. The results are shown in Figure 6.6.1. The pyrolysis was done similarly to other polymers previously discussed in this book at 600° C in He with the separation on a Carbowax column (see Table 4.2.2) and with MS detection. The peak identification for the chromatogram was done using MS spectral library searches and is given in Table 6.6.2. 

The enzymatic treatment of chitosan in the presence of tyrosinase and phenol derivatives produced new materials based on chitosan.91 During the reaction, unstable o-quinones were formed, followed by the reaction with the amino group of chitosan to give the modified chitosan. The tyrosinase-catalyzed modification of chitosan with phenols dramatically altered rheological and surface properties of chitosan. The modification with chlorogenic acid onto chitosan conferred the water solubility of chitosan under basic conditions.92 A new water-resistant adhesive was developed by the tyrosinase-catalyzed reaction of 3,4-dihydroxyphenethylamine and chitosan.93 Poly(4-hydroxystyrene) was modified with aniline by using tyrosinase catalyst.94 The incorporated ratio of aniline into the polymer was very low (1.3%). 

Apart from natural materials, oxidoreducates have been used to modify synthetic polymers. For example, using peroxidase, poly(4-hydroxystyrene) has been functionalized with aniline while poly(p-phenylene-2,6-benzobisthiazole) has been rendered more hydrophilic [22, 23]. Other authors have demonstrated that phenolics can be covalently bound to amino-functionalized polymers by using laccase resulting in increased fire resistance [13]A large number of scientific reports are available on enzymatic functionalization of poly(alkyleneterephthalate)s. Polyester fibers account for 73% of all synthetic fibers on the market with an annual production of approx. 27 million tons [24]. Similarly, polyamides and polyacrylonitriles have significant market shares. In contrast to natural polymers discussed above, hydrolases have shown higher potential for modification of these synthetic materials than oxidoreducates. 

Poly(4-hydroxystyrene) 298 24.0 Poly(vinyl ethyl ether) 298 19.5... 

The t-BOC protection group chemistry has been extended to other aqueous-base soluble polymers such as poly[styrene-co-N-(4-hydroxyphenyl)maleimide], ° poly(styrene-co-maleimide), poly(4-hydroxystyrene sulfone), and poly(4-hydroxy-a-methylstyrene) used in lithographic applications. Even novolac resins have been successfully protected with the t-BOC group,which has resulted in significant reduction of the DUV absorption of these resins. ... 

Scheme 7.33 Acid-catalyzed deprotection of poly(4-hydroxystyrene-co-4-polyhydroxy-styrene-tert-butyl ester).

Scheme 7.35 Synthetic routes to ESCAP resist polymer poly(4-hydroxystyrene-co-tert-butyl acrylate).

T. Iwamoto, M. Akita, T. Kozawa, Y. Yamamoto, D. Werst, D.A. Trifunac, and D. Alexander, Radi ation and photochemistry of onium salts acid generators in chemically amplified resists, Proc. SPIE 3999, 204 213 (2000) A. Nakano, K. Okamoto, Y. Yamamoto, T. Kozawa, S. Tagawa, T. Kai, H. Nemoto, and T. Shimokawa, Deprotonation mechanism of poly(4 hydroxystyrene) and its deriva tives, Proc. SPIE 5753, 1034 1039 (2005) T. Kozawa, A. Saeki, and S. Tagawa, Modeling and simulation of chemically amplified electron beam, x ray, and EUV resist processes, J. Vac. Sci. Technol. B 22(6), 3522 3524 (2004) T. Kozawa, A. Saeki, A. Nakano, Y. Yoshida, and S. Tagawa, Relation between spatial resolution and reaction mechanism of chemically amplified resists for electron beam hthography, J. Vac. Sci. Technol. B 21(6), 3149 3152 (2003). 

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