Luděk Toman

Multifunctional ATRP macroinitiators for the synthesis of graft copolymers

Abstract Multifunctional ATRP macroinitiators, polystyrene with 1-(2-bromopropionyloxy)ethyl or 1-(2-bromoisobutyryloxy)ethyl groups in the benzene rings and poly[4-methylstyrene- co -4-(bromomethyl)styrene], were synthesized. All the functionalized polymers were characterized by IR, 1 H and 13 C NMR spectroscopy and by size exclusion chromatography.

Thermally induced polymerization of isobutylene in the presence of SnCl4: Kinetic study of the polymerization and NMR structural investigation of low molecular weight products

The polymerization reactivity of isobutylene/SnCl4 mixtures in the absence of polar solvent, was investigated in a temperature interval from −78 to 60 °C. The mixture is nonreactive below −20 °C but slow polymerization proceeds from −20 to 20 °C with the initial rate r0 of the order 10−5 mol · l−1 · s−1. The rate of the process increases with increasing temperature up to ∼10−2 mol · l−1 · s−1 at 60 °C. Logarithmic plots of r0 and Mn versus 1/T exhibit a break in the range from 20 to 35 °C. Activation energy is positive with values E = 21.7 ± 4.2 kJ/mol in the temperature interval from −20 to 35 °C and E = 159.5 ± 4.2 kJ/mol in the interval from 35 to 60 °C. The values of activation enthalpy difference of molecular weights in these temperature intervals are ΔHMn = −12.7 ± 4.2 kJ/mol and −38.3 ± 4.2 kJ/mol, respectively. The polymerization proceeds quantitatively, the molecular weights of products are relatively high, Mn = 1500–2500 at 35 °C and about 600 at 60 °C. It is assumed that initiation proceeds via [isobutylene · SnCl4] charge transfer complex which is thermally excited and gives isobutylene radical-cations. Oxygen inhibits the polymerization from −20 to 20 °C. Possible role of traces of water at temperatures above 20 °C is discussed. It was verified by NMR analysis that only low molecular weight polyisobutylenes are formed with high contents of exo- terminal unsaturated structures. In addition to standard unsaturated groups, new structures were detected in the products.

Tailoring of polymers by combination of ionic and radical controlled polymerizations

Poly(methyl methacrylate)s with terminal bromine atom, prepared by bromination of anionically polymerized MMA, were used as ATRP macroinitiators giving di- and triblock copolymers with MMA, styrene and butyl acrylate blocks. Multifunctional ATRP macroinitiators were synthesized by introducing bromomethyl or 2-bromoacyloxy groups onto the main chain of polystyrene or poly(4-methyl styrene) and used for ATRP grafting of tert-butyl acrylate leading to densely grafted copolymers with more or less uniform grafts.

13C NMR characterization of unsaturated terminal structures in oligoisobutylenes

Summary13C NMR analysis revealed the existence of additional unsaturated terminal structures in oligoisobutylene samples, in addition to the well-known-CH2C(CH3)=CH2 and-CH=C(CH3)2. Structure with a double bond between two quaternary carbons was detected both in commercial Oppanol B3 and in a oligoisobutylene (PIB) sample prepared by polymerization in CH2Cl2 with a high concentration of monomer in the presence of BCl3 at-20°C. In the latter sample, another type of the structure with a double bond between quaternary carbon and methine carbon (-CH=C(CH3)-CH2CH3) was found in a large amount.

Effect of PVC on low-polar isobutylene polymerization in the presence of BCl3

SummaryThe isobutylene polymerizations in the presence of BCl3 were carried out in dichloromethane ([M]=7 mol/l) at-20°C in the presence and absence of PVC. The products of polymerizations in the absence of PVC are oligoisobutylenes with a narrow molecular weight distribution

Effect of PVC on low-polar isobutylene polymerization in the presence of BCl3. II: Vinyl chloride/2-chloropropene copolymer as an initiator

{\text{(}}\mathop M\limits^{\_\_\_} _{\text{W}} /\mathop M\limits^{\_\_\_} _{\text{n}} \approx {\text{1}}{\text{.3, }}\mathop M\limits^{\_\_\_} _{\text{n}} \approx {\text{2700)}}

Bottlebrush‐shaped copolymers with cellulose diacetate backbone by a combination of ring opening polymerization and ATRP

; their structure was analyzed by 1H-NMR spectroscopy. In addition to the signals assigned to known unsaturated terminal structures [δ 4.62 and 4.82-CH2C(CH3)=CH2, 5.12-CH=C(CH3)2], a new intense signal was found at δ 5.09 ppm and assigned to the structure-CH=C(CH3)CH2CH3. A mixture of isobutylene homopolymers