Cellulose diacetate (CDA) was acylated with 2-bromoisobutyryl bromide (BriBr) or with dichloroacetyl chloride (ClAcCl) giving polyfunctional macroinitiators for ATRP grafting of styrene (St), MMA and ...butyl acrylate (BuA). Under various reaction conditions, macroinitiators with variable degrees of functionalisation could be prepared. The macroinitiators with 2-bromoisobutyryl (BriB) groups were grafted with St or BuA, those with dichloroacetyl (ClAc) functions were used for graft copolymerization of MMA. Graft copolymers with chemically different grafts as well as tunable lengths and densities of grafts were synthesized in this way. Poly(CDA-
g-St) and poly(CDA-
g-MMA) were further used as macroinitiators of BuA polymerization, giving polyCDA-
g-(St-
b-BuA) and polyCDA-
g-(MMA-
b-BuA) graft copolymers with diblock grafts.
The model polyurethane foam and model compact polyurethane material were prepared and then decomposed by means of natural oils. Castor oil and fish oil based polyol were used in this study. Optimal ...conditions for the polyurethane decomposition were found. Temperature 250 °C was necessary for efficient polyurethane decomposition by castor oil whereas 200 °C is sufficient in the case of fish oil based polyol. Prepared products have hydroxyl number in the range of 95–168 mg KOH g
−1
. During the polyurethane decomposition no cleavage of double bonds in the fatty acid chains of castor oil and fish oil based polyol was observed.
Mesogenic thiols with azobenzene as a rigid part and with various substituent (H-, methoxy-, butoxy- or octyloxy-) in
para
-position of azobenzene ring were synthesized by multi-step syntheses. The ...thiols were grafted onto double bonds of telechelic poly(butadiene)diol (
M
n
~ 2,400, functionality
f
n
= 2, 60 mol.% of 1,2-butadiene units) via radical addition in the presence of 2,2′-azobis(2-methylpropionitrile) (AIBN). Initial mole ratio of thiol/double bonds varied in the range of 0.2–1.0. Influence of the azobenzene substituent on the extent of modification reaction was estimated using elemental analysis, size-exclusion chromatography and
1
H NMR spectroscopy. The substituent on mesogen plays also an important role in thermal behavior of both the thiols and the obtained comb-like polymers, as determined by differential scanning calorimetry and polarizing optical microscopy.
ATRP of methyl methacrylate (MMA), initiated with 1,3-bis{1-methyl-1-(2,2,2-trichloroethoxy)carbonylaminoethyl}benzene as a bifunctional initiator (BI) under CuCl catalysis was studied in the ...presence of 2,2′-bipyridine (bpy) or hexamethyltriethylenetetramine (HMTETA) ligands, in bulk or in toluene. With the bpy, the polymerization reaches only limited monomer conversions and products have broad MWDs. In contrast, polymerization in the presence of HMTETA is a well-controlled process, affords virtually quantitative conversion, giving PMMAs with narrow MWDs and predictable molecular weights within a range of more than one order of magnitude. NMR analysis of the prepared PMMA proved formation of linear polymers with im-measurable extent of chain branching or β-scission as undesired side reactions. The prepared α,ω-dichloro-PMMAs were used as macroinitiators for ATRP of
tert-butyl acrylate (
t-BuA), giving the corresponding triblock copolymers with narrow MWDs and molecular weights controllable in a wide range. Block copolymerizations were performed in dimethyl formamide (DMF) or acetone in the presence of pentamethyldiethylenetriamine (PMDETA) as ligand and could be accelerated by addition of metallic copper.
Methacrylate di- and triblock copolymers composed of methyl (MMA), butyl (BuMA), 2-(dimethylamino)ethyl (DMAMA), and 2-ethylhexyl (EtHMA) methacrylates and tert-butyl acrylate (t-BuA) blocks were ...prepared by ligated anionic polymerization and characterized by SEC and NMR. The process was initiated with the system methyl 2-lithioisobutyrate/lithium tert-butoxide (MIB−Li/t-BuOLi) at the 1/10 mole ratio, which was recently described as the optimum composition, at THF at −60 °C. The monomers were added to the reaction mixture successively after chosen polymerization intervals and products of the individual polymerization steps were isolated and analyzed. Molecular weights of methacrylate copolymers increased with increasing total amount of the monomers added, and the products of the two- or three-step polymerizations were not detectably contaminated with the products of the foregoing steps, so that the corresponding MWD curves were unimodal and symmetric. The product of MMA/t-BuA block copolymerization exhibited bimodal MWD, originating probably by the self-termination proceeding at the beginning of the second polymerization step after addition of an acrylate monomer to the “living” polymethacrylate. A possible mechanism of self-termination and reactions of polymethacrylate chains bearing a few terminal acrylate units are briefly discussed.
Polystyrene and polystyrene-
block-poly(methyl methacrylate) densely grafted with poly(ϵ-caprolactone) or poly(DL-lactide) in the benzene rings were synthesized by a “grafting-from” method using ...hydroxylated precursors of the above styrene polymers as macroinitiators of the ring-opening polymerization of appropriate monomers. The poly(ϵ-caprolactone) grafts of the polystyrene-
graft-poly(ϵ-caprolactone) copolymer were lengthened with poly(methyl methacrylate) by atom transfer radical polymerization. All the synthesized graft copolymers were characterized by
1H and
13C NMR spectroscopy and by size exclusion chromatography.
Synthetic potential of the ligated anionic polymerization (LAP) of acrylic and metacrylic esters initiated with methyl 2‐lithioisobutyrate (MIB‐Li) in the presence of an excess of alkali metal ...tert‐alkoxides (prevailingly Li tert‐butoxide) is presented. tert‐Alkoxides form with ester‐enolates, like MIB‐Li, cross‐aggregates of various composition, which tailor the environment of growing chain‐ends, lower their nucleophilicity and restrict in this way the extent of side reactions, in particular self‐termination of growing macroanions by back‐biting reaction. Thus, stability of polymethacrylate living chains is sufficiently high for methacrylate and acrylate block copolymers to be synthesized. In the case of acrylate polymerization, reaction conditions must be optimized due to their high tendency to self‐termination.
Diblock copolymers of methyl methacrylate (MMA) with 2-ethylhexyl, butyl, ethyl or
tert-butyl acrylate (EtHA, BuA, EtA,
t-BuA) have been prepared by the ligated anionic polymerization initiated with ...methyl 2-lithioisobutyrate (MIB-Li) in the presence of an excess of Li
tert-butoxide (
t-BuOLi) in toluene/THF mixture at −60 or −78
°C. The copolymers, prepared at −60
°C, show MWD with a hint of bimodality, indicating partial deactivation of the living PMMA upon addition of acrylic monomer. At −78
°C, the extent of this deactivation is distinctly lower, the formed block copolymers, in particular, poly(MMA-
b-EtHA), have unimodal MWD and exhibit tails only in the lower-molecular-weight region. Poly(MMA-
b-EtHA)s were extracted with acetonitrile dissolving PMMA; very small parts of the crude products dissolved, whereas prevailing parts remained as solids documenting thus formation of block copolymer in a high yield. Surprisingly, the highest amount of self terminated PMMA was found in block copolymerization of MMA with
t-BuA at both the temperatures, the products of which had clearly bimodal MWDs. This finding is shortly discussed on the basis of relatively slow propagation of
t-BuA in comparison with EtHA, BuA and EtA.
