Crosslinking chain scissions

Select examples of organosilicon resist chemistries that undergo crosslinking, chain scission or solution inhibition. 

Thermal analysis (DSC, DMTA, DETA, etc.) gives valuable information on eventual changes of glass transition temperature, which can be interpreted in terms of crosslinking/chain-scission processes. 

Polyethylene oxide reactions were thoroughly investigated by Fisher etal. [376]. The G values for crosslinking, chain scission and volatile formation for electron irradiation at 14°C and a dose rate of 600 Mrad h 1 are given in Table 27. To account for these values, the mechanism proposed was... 

Fig. 18. Arrhenius plot of quantum yields for poly vinylacetate photolysis as a function of temperature A crosslinking, chain scission [reproduced with permission from Ref. 86].

Most organic materials contain sites where radicals can form more or less easily, depending upon structure. Only perfluorinated molecules are totally free of such sites since radical formation usually involves abstraction of hydrogen radicals. Both the polymer and abstracted hydrogen radicals become stabilized by the intervention of oxygen. Degradation in the form of crosslinking, chain scission or both follows. The... 

The standard measurement of the yield for an event resulting from the irradiation process is expressed as the G factor. This factor is universally accepted [16] and is defined as the event yield per 100 eV of energy deposited in the material. The SI unit for G is xmol For the purposes of this review events per 100 eV will be used throughout. The most commonly quoted G factors are for crosslinking, chain scission, and gas evolution, G(X), G(S), and G(Gas), respectively. There may be several different values for the G-factor in the literature since several different methods of measurement may be used to determine the event yield. If different methods or standards are used to determine molecular weights, they can lead to widely different G-factors. For example, in the case of a low density polyethylene values for G(X) of 0.9 or 1.7 are obtained using the hydrogenated polybutadiene or polystyrene calibrations, respectively [17]. 

PEST Ferrocene, Co octoate, water, naphthalene, keto-esters FVee radicals, adds, aromatic compounds, crosslinks, chain scissions Free radicals, hydroperoxides, carbonyl compounds, chain scissions... 

Products of degradation - radicals, hydroperoxides, epoxy groups, ketone groups, crosslinking, chain scission ... 

Products of degradation - yellowing, conjugated double bonds, crosslinking, chains scission, carbonyls ... 

Physical damage as surface cracks might be reversed by reprocessing while for chemical changes such as crosslinking chain scission, and new formation functional groups are irreversible. 

Most oxidations are accompanied by degradation and chain breaking. Thus when a polymer containing a double bond is irradiated in the presence of singlet oxygen a hydroperoxide is formed on the a-carbon of the double bond however it rapidly decomposes to generate free radicals which initiate side reactions (crosslinking, chain scission, etc). The same observation is valid for poly-alkenes. ... 

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