TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The free radical initiator is acyl peroxides, diacyl peroxides, peroxides, azo compounds, perfluoroacyl peroxides, ammonium persulfate, potassium persulfate, disuccinic acid peroxide, potassium permanganate and sulfite/persulfate systems. The free radical initiator has a structure of formula (CF3CF2CF2OCF(CF3)(C=O)OO(C=O)CF(CF3)OCF2CF2CF3). The monomer B is 1,1-difluoroethylene (E), TFE, VF, VF2, PDD, PPVE, PMVE, PEVE, HFP, CTFE, 3FE or EVEOCN. The monomer A is EVE, 8-CNVE and (CF2=CFO(CF2)5CN), and monomer B is E, TFE, VF, VF2, PDD, PPVE, PMVE, PEVE, HFP, 3FE, CTFE or EVEOCN. The photocrosslinked copolymer is poly(TFE/PMVE/PEVE/8-SAVE). EXAMPLE - Autoclave was chilled to -20 degrees C and 2,2,3,3-tetrafluoro-3-(1,2,2-trifluoro-1-trifluoromethyl-2-trifluorovinyloxy-ethoxy)-propionic acid methyl ester (42 ml) and (2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)propanoyl) 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)propaneperoxoate initiator (10 ml) were added. The autoclave was evacuated and ethylene (3 g) was added. The resulting hazy fluid was transferred to lined tray and allowed to evaporate first at ambient temperature. The residue still weighed 22.4 g after another 24 hours. Then lump of poly(2,2,3,3-tetrafluoro-3-(1,2,2-trifluoro-1-trifluoromethyl-2-trifluorovinyloxy-ethoxy)-propionic acid methyl ester/1,1-difluoroethylene) (poly(EVE/E)) (0.52 g) was placed on a glass microscope slide and the slide put in a 95 degrees C oven for 1 hours, the poly(EVE/E) was found to have transformed from a tacky glue-like material that was readily soluble in 2-heptanone to a nontacky, modestly elastomeric polymer that swelled but did not dissolve in 2-heptanone. Three glass slides were spotted with lumps of poly(EVE/E) (0.2 g) and put in a 150 degrees C oven for 15 minutes, causing the poly(EVE/E) samples to 25 spread out as films of 23 mils thick. These slides were then placed under a 1 kW deep-UV short arc lithographic lamp, with a light intensity at the sample plane of 11.5 milliwatts/cm2, the polymer was found to be silky smooth to the touch, to spring back when indented with a fingernail, and to form a gel when mixed with 2-heptanone to give the photocrosslinked copolymer.