In order to obtain comb‐like poly‐L‐lysines bearing a biphenyl mesogen at the end of every repeating unit we have synthesised Nε‐4‐phenylbenzamido‐L‐lysine (Kφφ) and the corresponding N‐carboxy anydride (Kφφ‐NCA). We have homopolymerised the Kφφ‐NCA and block‐copolymerised it with the NCA of Nε‐trifluoroacetyl‐L‐lysine (Kt). The structural study of homopolymers pKt and pKφφ and block copolymers pKt/pKφφ was performed by infrared spectroscopy and X‐ray diffraction. Two main types of structures were established: a bidimensional hexagonal one (Hα) where the polypeptide chains adopt an α‐helix conformation and a lamellar smectic one (SA) deriving from the β‐pleated‐sheet structure of polypeptides. Homopolymers pKt and block copolymers pKt/pKφφ rich in pKt exhibit the Hα structure, whereas the homopolymers pKφφ exhibit an SA2 structure, and block copolymers rich in pKφφ exhibit an SAd structure. All the liquid‐crystalline structures were stable until the beginning of decomposition of the polymers. Hydrolysis of the pKt block of copolymers pKt/pKφφ provided amphiphilic block copolymers pK/pKφφ without modification of the structure of the mesophases.
The free radical copolymerization of allyl ribosides with diethyl fumarate and maleate was investigated for evaluating the potential of donor-acceptor type copolymerization applied to unsaturated monomers derived from renewable feedstock. The photochemically induced polymerization of model monomer blends was conducted in solution as well as in liquid films of bulk reactants. Infrared spectroscopy was used to monitor the consumption of the allylic donor monomer and of the butenedicarboxylate acceptor monomers. The method allowed examining the influence of the nature of the monomer pair and of their relative concentration on the kinetic profiles. Comparison with reference vinyl ether monomers confirmed the expected lower reactivity of the blends containing allylic derivatives. SEC and NMR analysis supported the occurrence of degradative chain transfer during the reactions involving allylic monomers. However, allyl derivatives of glycerol as well as O-allyl ribosides were shown to undergo polymerization with high conversion of both monomers when blended in appropriate molar ratios.
Hyperbranched aliphatic polyesters of 2,2′‐bis‐(hydroxymethyl) propanoic acid and hyperbranched aliphatic polyamides obtained from new carboxy‐ and amino‐functionalized caprolactams were studied by NMR spectroscopy and MALDI‐TOF mass spectrometry. Ring‐chain equilibria taking place through intramolecular hydroxy‐ester, carboxy‐amide or amine‐amide interchanges and leading to the formation of cyclic branches or end‐groups were found to exert a predominant influence on the molar mass of these hyperbranched polymers. A number of intra‐ or intermolecular side reactions, such as the formation of ethers in polyesters and the formation of anhydrides, imides, amidines and secondary amines in polyamides were also detected and resulted in polymer crosslinking on prolonged heating. The existence of such ring‐chain equilibria and side‐reactions make the control of hyperbranched polymer structure much more difficult than generally accepted.
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