NOVELTY - Modifying (M1) a polymer having dithiocarbamate moieties of specific formula involves reacting the polymer with an acid.    USE - For modifying a polymer having dithiocarbamate moieties to form a modified polymer, which is useful in a device e.g. semiconductor device, solar cell, light-emitting diode, chemical sensor, biological sensor, chemical sensor and integrated circuit (claimed).    ADVANTAGE - The method (M1) is cost-effective and environmental-friendly, and improves the conversion of dithiocarbamate-containing precursor polymer into a conjugated poly (arylene-vinylene) such as poly(1,4-phenylene vinylene) (PPV) or poly(2,5-thienylene vinylene) (PTV) by overcoming the drawbacks and limitations such as insolubility due to their rigid backbone, and high reactivity of intermediates. The method (M1) allows easy chemical modification, e.g. functionalization, of a precursor polymer obtained via the dithiocarbamate precursor route. Such a modification is used to introduce in an easy and controllable way chemical functions, which is used in further polymerization reactions.    DETAILED DESCRIPTION - Modifying (M1) a polymer having dithiocarbamate moieties of formula -(Ar-C(S-C(=S)(NR1R2)(R3)-CH(R4))n- (I) involving reacting the polymer (I) with an acid.    Ar=arylene or heteroarylene (optionally substituted by at least one of 1-20C alkyl, 1-20C alkoxy, 1-20C alkylsulfate, aryl or aryl-(1-4C) alkyl);    R1 and R2=1-20C alkyl, 3-10C cycloalkyl, aryl, aryl-(1-20C) alkyl or heterocyclyl;    R3 and R4=H, 1-20C alkyl, 3-10C cycloalkyl, aryl, aryl-(1-4C) alkyl or heterocyclyl;and    n=integer to provide the number average molecular weight of 5000-1000000 Dalton.    INDEPENDENT CLAIMS are included for the following:    (1) new polymer of formula (II); and    (2) a device comprising at least one layer of the polymer (II), or the polymer modified by the method (M1).    R'1 and R'2=1-20C alkyl, 3-10C cycloalkyl, aryl, aryl-(1-4C) alkyl or heterocyclyl;    R'3 and R'4=H, 1-20C alkyl, 3-10C cycloalkyl, aryl, aryl-(1-4C) alkyl or heterocyclyl;    m=value to provide the average number molecular weight of 5000-1000000 Dalton (preferably at least 1);    p and q=integer to provide the average number molecular weight of 5000-1000000 Dalton (preferably 0);    Nu'=OR'5, SR'5, NHR'6, OC(O)R'5, or SC(O)R'5;and    R'5 and R'6=1-20C alkyl, 2-20C alkenyl, aryl or aryl-(1-4C) alkyl.    The integers p and q can be 0, and m is at least 1.