INVESTIGADORES
MARTINO Debora Marcela
congresos y reuniones científicas
Título:
Syntesis, curing and applications of bioinspired polymers based on vinylbenzil thymine
Autor/es:
A. BARBARINI; D. M. MARTINO; M SPONTON; D. A. ESTENOZ; G. MEIRA
Lugar:
Cancun
Reunión:
Congreso; XX International Materials Research Congress (IMRC); 2011
Resumen:
Bioinspired polymers based on a new
synthetic monomer, 4-vinylbenzyl thymine (VBT), have been designed to have the
ability to photo-crosslink upon irradiation with short-wavelength UV light. Water-soluble
environmentally benign, non-toxic and recyclable
polymers can be obtained copolymerizing photocrosslinkable VBT with
para-substituted charged styrenic monomer vinylbenzyl triethylammonium chloride
(VBA). The VBT-based photo-polymers have potential applications in a variety of
fields ranging from hair care products to printed circuit boards and
photo-imaging systems, as well as controlled release systems for pharmaceutical
and agricultural use.
Syntheses
of VBTVBA random copolymers at various comonomer ratio and initiator
concentrations were carried out at 65 ºC using isopropanol as solvent. Samples
were taken along the reactions to determine the monomer conversion, chemical
composition and molecular weight distribution. The comonomers exhibited similar
reactivities and random copolymers with different chemical compositions were
obtained. The curing process involved the irradiation of the copolymer films
with short UV light (254 nm) for different times. Cross-linked areas becomes insoluble due to increased molecularweight leading to film immobilization on the
substrate, while uncross-linkedregions may beremoved by washing with water. The light-induced
crosslinking reaction was followed by UV-vis spectroscopy and the
immobilization point was determined. The kinetics of the crosslinking process
pointed to a second-order process with respect to thymine concentration [1].
The experimental results provide complementary information on photo-induced
immobilization of VBTVBA films that are crucial for developing new classes of
environmentally benign materials.
On the other hand, we used controlled radical polymerization techniques
(Nitroxide Mediated, NMP and Atom Transfer, ATRP) to produce
amphiphilic block copolymers of VBT-VBA. The polymer chains are able to self-assemble
into micelles at certain concentrations, where the hydrophobic
core of pVBT allows
transporting hydrophobic drugs of biomedical interest through hydrophilic media,
acting as drug delivery systems. The crosslinking of the core
by UV light dimerize adjacent thymines increasing the stability of the micelle
and allowing a slower drug release. Bulk polymerizations of styrene (St) in Dimethylformamide (DMF) at
130ºC under N2 atmosphere were carried out using TEMPO as
polymerization mediator. Conversion andmolecular weight distribution (MWD),
average molecular weights (Mn) (Mw)and polydispersity (Ip) were
determined. To obtain di-block
copolymers, polymerization of VBT from pSt macro-initiator were carried out in
DMF at 130°C under nitrogen atmosphere. The MWD shows an increase in the
average molar mass, with low Ip variation. We plan to synthesize VBT-VBA block
copolymers in aqueous systems, with the goal of obtaining block amphiphilic
copolymers for use in controlled drugs release systems.