TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): Preparation of (I) comprises: contacting 3-allyl-3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepine or 3,3-diallyl-3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepine with a thiol having a hydrocarbyl moiety (optionally containing at least one heteroatom-containing functional group) under radical addition conditions, to give (I). Preferred Components: The compound having at least two thiol groups is of formula ((HS-CH2CH2C(=O)OCH2)bCH4-b). Preferred Method: The polymer (P1) is prepared by copolymerizing (I) and one additional monomer, and the polymer (P2) is prepared by copolymerizing the crosslinker and at least one additional monomer, where the additional monomer is ProDOT, 3,4-ethylenedioxythiophene, or 3-allyl-3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepine. The monomer or the crosslinker is polymerized by electropolymerization. Preferred Definitions:    R1 = -(CH2)3-Si(OR2)3, -(CH2)3-SO3H and its salts, -CH2-COOH and its salts, -CH2CH(NH2)C(=O)-Arg-Gly-Asp, -CH2CHOHCH2OH, -(CH2)2NH2 and its salts, -(CH2)6SH, -CH2CH2-(OCH2CH2)c-OH, ethylhexyl, or glucosyl;    R2 = 1-4C alkyl;    c = 0-100; and    Z = (-CH2CH2C(=O)OCH2)bCH4-b    SPECIFIC COMPOUNDS - 8 Compounds (I) are disclosed e.g. (3-(3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepin-3-yl)-propylsulfanyl)-acetic acid of formula (Ia), 3-(3-(3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepin-3-yl)-propylsulfanyl)-propane-1,2-diol, 2-(3-(3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepin-3-yl)-propylsulfanyl)-ethylamine, 3-(3-(2-ethyl-hexylsulfanyl)-propyl)-3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepine, and (3-(3-(3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepin-3-yl)propylthio)propyl)trimethoxysilane.    EXAMPLE - 3,4-Propylenedioxythiophenylene (100 mg) and thioglycolic acid (70 mg) were added to a vial along with 2,2-dimethoxy-2-phenylacetophenone (0.1 wt.%). The mixture was vortexed to ensure thorough mixing and dissolution of the initiator. The vial was placed under a UV lamp and irradiated for one hour. Then, a small amount of methanol was added, and the product was precipitated using water. The supernatant was decanted and the product was redissolved in ethyl acetate, dried with magnesium sulfate, and concentrated by evaporation to give (3-(3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepin-3-yl)-propylsulfanyl)-acetic acid (114 mg).