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The polymerization of ethylene and propylene and the copolymerization of ethylene and hexene-1 with a Ti(O-iso-Pr) 4 -AlR 2 Cl/MgBu 2 catalyst system have been studied. The advantages of this system over metallocene and postmetallocene catalysts are high activity, low cost, and ease of synthesis. The resulting polymers and copolymers are characterized by a broad molecular-mass distribution, which reflects the heterogeneity of the active sites with respect to kinetic parameters. As a consequence, the ethylene/hexene-1 copolymers exhibit compositional heterogeneity. The active sites of the system produce copolymers with a pronounced tendency toward alternation of monomer units. The propylene polymerization product is mostly amorphous atactic polypropylene.

Donor-acceptor conjugated polymers are considered advanced semiconductor materials for the development of thin-film electronics. One of the most attractive families of polymeric semiconductors in terms of photovoltaic applications are benzodithiophene-based polymers owing to their highly tunable electronic and physicochemical properties, and readily scalable production. In this work, we report the synthesis of three novel push–pull benzodithiophene-based polymers with different side chains and their investigation as hole transport materials (HTM) in perovskite solar cells (PSCs). It is shown that polymer P3 that contains triisopropylsilyl side groups exhibits better film-forming ability that, along with high hole mobilities, results in increased characteristics of PSCs. Encouraging a power conversion efficiency (PCE) of 17.4% was achieved for P3-based PSCs that outperformed the efficiency of devices based on P1, P2, and benchmark PTAA polymer. These findings feature the great potential of benzodithiophene-based conjugated polymers as dopant-free HTMs for the fabrication of efficient perovskite solar cells.

The influence of small additives of cobalt(II) porphyrin (Co II Pn) on cross linking radical polymerization of butane 1,4 diol dimethacrylate and its structural analog butane 1,4 diol diacrylate was studied. The kinetics of cross linking radical polymerization of di(meth)acrylates in the absence and presence of Co II Pn and the diffusional sorption and physical mechanical properties of the resulting polymers were studied. Cobalt(II) porphyrin decreases substantially the polymerization rate and partially suppresses the gel effect. Diacrylate polymerization in the presence of Co II Pn proceeds with an induction period, whose value is determined by the content of Co II Pn. Cobalt(II) porphyrin modifies the structure and properties of the formed cross linked polymers. In the case of dimethacrylate, this is caused by the catalytic chain transfer reaction, whereas for diacrylate the reason is the reversible inhibition reaction.In cross linking radical polymerization of polyfunc tional monomers, the growth of linear chains bearing "pen dant" double bonds is accompanied by intramolecular cyclization and intermolecular and intramolecular cross linking in branched macromolecules, microgel particles, and macrogel. 1,2 As a result, special topological (small cycles) and morphological (microgel particles, grains) structures are formed in the polymer, and the cross linked polymer formed is characterized by a high degree of struc tural heterogeneity. 1,2 The process of structure formation of cross linked polymers can be controlled successfully by inhibitors of radical polymerization (nitro and nitroso compounds), 3 standard (thiols) 4,5 and catalytic (cobalt(II) macrocycles) 6-9 chain transfer agents, and agents of liv ing radical polymerization (alkoxyamines, transition metal complexes, iniferters). 10-12 The use of them makes it pos sible to control the contribution of reactions of polymer chain propagation, cyclization, and cross linking to the total conversion of C=C bonds.Cobalt(II) macrocycles based on porphyrin, phthalo cyanine, and cobaloxime demonstrate high efficiency as controlling additives. These compounds are widely used in radical polymerization of monofunctional mono mers to prepare oligomers or polymers with low degree of polymerization. 13,14 The main regularities of catalytic reactions that occur in the presence of the cobalt(II) macrocycles were established for vinyl monomers of dif ferent structure. 14 The radical polymerization of vinyl monomers with addition of cobalt(II) macrocycles, in particular, Co II Pn, is accompanied by the following re actions:where R n • , R m • , and R 1 • are radicals with degrees of polymerization of n, m, and 1, respectively; M is mono mer, HCo III Pn is hydride, Z n = is oligomer or polymer with the terminal double bond, and R n -Co III Pn is an active intermediate with the C-Co bond formed due to the reaction of the R n • radical with Co II Pn. Reac tions (1)-(2) are known as catalytic chain transfer, and reactions (3) and (4) are catalytic and reversible inhibi tions, resp...

It is shown that branched and highly branched vinyl polymers can be prepared by three dimen sional radical polymerization in the presence of dissolved oxygen, as exemplified by the oxidative copolymer ization of styrene and divinylbenzene. The conditions of synthesis of highly branched polymers with a high yield-the ratio between monovinyl and divinyl comonomers and the rate of oxygen bubbling-are deter mined. The kinetics of formation of branched polystyrenes and the features of their molecular mass distribu tion are studied. Elemental analysis data show that the polymeric product contains 22-24 wt % oxygen, which, according to the IR data, enters into the composition of carbonyl, hydroxyl, and peroxide groups. The thermal decomposition of polymeric products is investigated via the TGA-DSC method. The main exother mal peak at ~145°C is associated with the decomposition of peroxide groups, which is accompanied by the evolution of formaldehyde.