A method of surface functionalization of ceramics with monolayers and surface grafted polymer
layers is described. A phenylsilane monolayer is created on the substrate's oxide surface by using
phenyltrichlorosilane as the silane coupling agent. To control the formation of the monolayer and ensure the
growth of a dense, homogeneous layer, the ceramic surface is first dried and then a controlled amount of
water is adsorbed onto it, and a hindered organic base is added to the phenyltrichlorosilane solution to absorb
acid generated in the reaction of the silane coupling agent with hydroxyl groups on the ceramic surface. This
procedure results in dense homogeneous phenylsilane monolayers on a variety of surfaces, including silicon,
Pt/PtO, and quartz. These layers can now be functionalized by addition of triflic acid, which removes the
phenyl ring as benzene, and introduction of a nucleophile. Monolayers of −C⋮CH, −OCH2CF3, [(OCH2CH2)2O], −OCH2CF2CF3, and −O(CH2)6NH2 were generated in this fashion, all proving to be continuous and
homogeneous. In addition, the cationic silyl triflate site generated by the removal of the phenyl ring is capable
of initiating polymerization to form covalently bound polymer layers on the surface. Polymer layers of poly(methyl methacrylate), poly(propylene oxide), and poly(dimethylsiloxane) were generated in this manner; in
the case of poly(dimethylsiloxane), layers up to 300 Å thick were formed. Anionic initiation of polymerization
is also possible, using a bromopropyl trichlorosilane coupling agent to form the initial monolayer, followed by
lithiation with lithium di-tert-butylbiphenyl. Acrylonitrile can be anionically polymerized to films of up to
2450 Å in thickness. The monolayers and polymer layers were characterized by XPS, AFM, contact angle
measurements, and profilometry and were found to be continuous. The initial phenylsilane monolayer can be
lithographically patterned by using 193 nm light to cleave the surface phenyl groups; the remaining groups
can then be functionalized as discussed above to create surface-grafted patterned polymer layers.
The synthesis of poly(phenylcarbyne), one of a class of carbon-based random network polymers, is reported. The network backbone of this polymer is composed of tetrahedrally hybridized carbon atoms, each bearing one phenyl substituent and linking, by means of three carbon-carbon single bonds, into a three-dimensional random network of fused rings. This atomic-level carbon network backbone confers unusual properties on the polymer, including facile thermal decomposition, which yields diamond or diamond-like carbon phases at atmospheric pressure.
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