Cotton fibers encapsulated with homo- and block copolymers: synthesis by the atom transfer radical polymerization grafting-from technique and solid-state NMR dynamic investigations.
Cotton fibers were modified by surface-initiated atom transfer radical polymerization of ethyl acrylate (EA) followed by copolymerization with styrene. Either ethyl 2-bromopropionate as a sacrificial free initiator or Cu(II) as a deactivator was used to optimize the EA grafting yield and to preserve the livingness of the chain ends for the subsequent growth of a poly(styrene) (PSty) block from the poly(ethyl acrylate) (PEA) grafts. The polymer-encapsulated cotton fibers were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and solid-state NMR (high-resolution 13C cross-polarization magic angle spinning, 1H spin-lattice relaxation times, and 1H free induction decay analysis NMR). The latter allowed the detection of the dynamic modifications associated with the presence of homo- and block copolymer grafts. In particular, the results of the DSC and NMR investigations suggest a heterogeneous morphology of the g-PEA-b-PSty grafted skin, which could be described as an inner layer of g-PEA sandwiched between the semicrystalline cellulose of the core fiber and the high glass transition temperature PSty of the covalently linked outer layer. Such morphology results in a reduced molecular mobility of the PEA chains.
Castelvetro
Valter
V
Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Risorgimento 35, 56126 Pisa, Italy. vetro@dcci.unipi.it
Geppi
Marco
M
Giaiacopi
Simone
S
Mollica
Giulia
G
D000179:Acrylates; D032561:Cotton Fiber; D009682:Magnetic Resonance Spectroscopy; D044367:Phase Transition; D011108:Polymers / Q000138:chemical synthesis*; D020058:Styrene
D000179:Acrylates; D011108:Polymers; D020058:Styrene; C040833:ethyl acrylate