A series of aliphatic polycarbonates based on the condensationcopolymerization of thebischloroformate of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCBD)with itself
and the diolsof 3-cyclohexene-1,1-dimethanol, 1,4-cyclohexanediol (CHD), in variousmolar ratios,
exo,
exo-tricyclo[2.2.1.0
2,6]heptane-3,5-diol,
and4,8-bis(hydroxymethyl)tricyclo[5.2.10
2,6]decane(BTD)were synthesized. Incorporation of cyclic
and tricyclic repeatunits produced polycarbonateswith high glass transition temperatures (
Tg's),high molecular weights,
and low refractiveindexes. The crystallinity of the TMCBD homopolymer was minimizedin the CHD/TMCBDcopolymers with little effect on
Tg but withdecreased thermal stability. Thermal analysisyields decomposition temperatures ranging from 354
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C for the TMCBDhomopolymer to292-298
![](/images/entities/deg.gif)
C for the CHD/TMCBD copolymers; all polymers undergocomplete thermaldegradation. Refractive indexes range from 1.493 for the 1:1copolymer of BTD
and TMCBDto 1.481 for the CHD/TMCBD copolymers. Thin films composed of analiphatic polycarbonate
and a base-releasing cobalt(III) photoinitiator can be imaged withdeep-UV light. Thepolycarbonates selected for study were the 9:1 copolymer of CHD
andTMCBD
and the 1:1copolymer of BTD
and TMCBD. The first step of image formation isthe efficient photoredoxdecomposition of the photoinitiator with the release ofmultiequivalents of Lewis base. Inthe case of[Co(en)
3](BPh
4)
3 (en isethylenediamine, BPh
4- is tetraphenylborate),photogenerated ethylenediamine cross-links the polymer chains via formation ofbis(dicarbamate)linkages. Development with solvent dissolves the unirradiatedareas to yield negative-toneimages. For[Co(NH
3)
6](BPh
4)
3,photoreleased ammonia causes chain scission in the exposedregions of the film,
and wet or dry development results inpositive-tone images.