Poly methyl isopropenyl ketone

Photodegradation of poly(methyl isopropenyl ketone) (3.18) occurs by the following mechanism, which includes [1979]  

The depolymerization reaction is enhanced by temperature. At high temperatures (150-190°C) a large amount of pure monomer is evolved [2283]. 

Photodegradation of copolymers phenyl vinyl ketone with styrene (3.19) or a-methylstyrene occurs by both the Norrish type I (a-cleavage)  

Main chain scission also occur via j -cleavage  

The quantum yield of chain scission is dependent on the glass transition temperature (Tg) (cf. section 1.9). 

---

Poly(methyl isopropenyl ketone) + 114 +243 Interchain attraction... 

Various materials have been examined for use as deep UV resists poly(methyl methacrylate) (PMMA) (1), poly(methyl isopropenyl ketone) (PMIPK) fS.7L and the novolak-Meldrum s acid solution inhibition system (S). Each however has a problem related to sensitivity and/or resolution. While PMMA is insensitive to light of X > 230 nm because of its weak absorption, its high resolution properties make it an attractive starting point for the design of a resist that will perform well in the 230-280 region. The photochemical properties of PMMA could be modified by the incorporation of a small percentage of photolabile groups so as to have both the desired sensitivity and base polymer properties. 

POLY (METHYL ISOPROPENYL KETONE) (PMIPK) (ODUR-1010 (TOKYO OHKA) - , -CH -c- I COCH3 230-320 (max 290) 5 24... 

A modification of these systems involving replacement of poly (4-vinylphenol) with poly(methyl isopropenyl ketone) (PMIPK) was reported by Nakane and co-workers (41). Although PMIPK is a positive-acting singlecomponent resist in the deep UV, it functions as a negative resist when mixed with an aromatic bisazide such as 2,6 di(4-azidobenzylidene)-4-... 

Poly(vinyl ketones) such as poly(ethylene-a//-carbon monoxide) CAS 111190-67-1, poly(methyl vinyl ketone) CAS 25038-87-3, and poly(methyl isopropenyl ketone) CAS 25988-32-3, also have practical applications. For example, poly(ethylene-a/f-carbon monoxide) is used in photodegradable plastics and in various copolymers. Several studies were reported regarding the thermal stability of these polymers. It has been shown that poly(ethylene-a/f-carbon monoxide) decomposes upon heating with chain scission generating small molecular weight alkenes and ketones. Some literature reports discussing the thermal decomposition of poly(vinyl ketones) are summarized in Table 6.5.5 [13]. 

Formation of some aromatic compounds show that further eliminations after the aldol condensation may take place with formation of phenol derivatives. Also, larger fragments seen in the last part of the pyrogram show that the backbone of the polymer is not cleaved only in the manner involved in the formation of 3-methyl-2-cyclohexene-1-one. Similar pyrolysis occurs for poly(methyl isopropenyl ketone), which starts decomposing at about 250° C (a change in color starts at 170° C), also undergoing an aldol condensation. 

Poly(methyl a-chloroacrylate) Poly(2-chloroethyl methacrylate) Poly(2-chlorocyclohexyl methacrylate) Poly(methyl isopropenyl ketone) Polymethacrylonitrile Polyacrylonitrile... 

Another group of positive UV resists operating on the principle of radiation-induced main chain scission utilizes the efficient photochemistry of polymeric ketones, exemplified hy poly(methyl isopropenyl ketone) PMIPK, to effect image discrimination. Scheme 7.21 shows the photolysis of this resist. ... 

Tsuda, et al., Spectrally sensitized decomposition of poly(methyl isopropenyl keton) Novel deep UV resists, Photogr. Sci. Eng. 23, 290 (1979). 

Poly(methyl-isopropenyl-ketone) (PMIPK) < H3 —c—c H2 I r° CH3 n 2,6-Di(4- azido benzylidone)- 4-methylcyclo- hexanone 100 ONR20 25... 

The low chemical and thermal stability of poly(vinyl ketones) leads to a sensitivity to degradation reactions. Poly(methyl isopropenyl ketone) lost water at about 250 °C, to yield glassy, red, non-crosslinked products. It was proposed that an intramolecular aldol... 

UV and y-radiation of poly(methyl isopropenyl ketone) produced random chain scission at 23 °C. The presence of air increases unexpectedly the main chain scission of the polymer under y-radiation [377]. In a series of publications [378] the radiolysis and photolysis of poly(phenyl vinyl ketone), poly(vinyl benzophenone), and poly(/-butyl vinyl ketone) [357] were described. The authors stated that photodegradation of poly (phenyl vinyl ketone) occurred by the abstraction of a hydrogen in the y-position to a carbonyl group, followed by chain scission by a Norrish type II photoelimination mechanism. 

---