ELFT HÍRADÓ

[László Bottyán <bottyan.laszlo AT wigner.mta.hu>]

A Budapesti Neutronközpont következő szemináriumi előadása:

"Erősen hidrofil polimer bevonatok neutronreflektometriai vizsgálata"

Előadó:                Nagy Béla
       Linköping University, Sweden (bela.nagy AT liu.se)

Helyszín: KFKI kampusz XIX. épület földszinti Tanácsterem
Időpont:  2019. szeptember 23. hétfő 14:00

A magyar nyelvű előadás angol nyelvű kivonata:


Neutron reflectometry studies of strongly hydrophilic polymer coatings

Bela Nagy, Jing Jin and Thomas Ederth

IFM, Division of Molecular Physics, Linköping University, Sweden

The accumulation of undesired biomaterials onto surfaces (‘biofouling’) is 
a problem in both industry and healthcare [1]. One of three main paths in 
marine anti-fouling involves hydrophilic materials that bind water 
strongly [2]. This hinders the foulant from attaching, since the bound 
water must be removed first. This strategy aligns well with the 
requirements for biomedical, as well as several food and pharmaceutical 
applications, were other approaches, such as the use of toxins, are not 
applicable. Thus, exploration of this strategy is of broad and general 
interest in anti-fouling research. Poly(ethylene glycol) (PEG) is 
currently the gold standard of such coatings, despite its shortcomings in 
environmental stability [3]. Materials combining the functionality of PEG 
and the stability of poly(methyl methacrylate) were intensively studied 
and thin films made from 1:1 mixtures of 2-hydroxethyl methacrylate and 
oligo(ethylene glycol) methacrylate were tested in anti-fouling assays. 
The assays showed an unexpected optimum film thickness, in both the 
anti-fouling performance and hydration, without an obvious explanation 
[4]. Other examples of such coatings are zwitterionic polymers that have 
both anionic and cationic functional groups. They bind water strongly 
through polar interactions, but their zero net charge means they do not 
participate in Coulomb interactions with foulants. To bypass the 
difficulties arising from the synthesis of zwitterionic monomers, 
co-polymers of oppositely charged monomers, also referred to as 
pseudo-zwitterionic co-polymers, are explored and used as model systems. 
Studies performed on cationic poly(2-aminoethyl methacrylate) and anionic 
poly(2-carboxyethyl acrylate) grafted sequentially with the top layer as a 
thickness gradient, show that optimal fouling resistance exist in a 
well-defined region along the gradient, and that the position of the 
optimum depends on the pH. [5] This is explained by a model that 
correlates the optimum to a highly condensed, charge-balanced region of 
the gradient.

In this work we use neutron reflectometry and spectroscopic ellipsometry 
to investigate the mixing and swelling of poly(2-methylacrylic 
acid-co-2-aminoethyl methacrylate) copolymer hydrogels and the thickness 
and grafting density dependence of the hydration of poly(2-hydroxethyl 
methacrylate-co-oligo(ethylene glycol methacrylate)) brushes. Utilizing 
the difference in neutron contrast for deuterium and hydrogen, we use 
deuterated monomers to determine the depth profile of the monomer ratio, 
and water contrast variation to determine the hydration profile of the 
films.

References
[1] Callow, M. E. and Callow, J. A. Biologist, 49(1), 1-5, (2002).
[2] Banerjee, I. et al., Adv. Mater., 23, 690–718, (2011)
[3] Branch, D.et al., Biomaterials, 22(10), 1035–1047, (2001)
[4] Yandi, W.et al., ACS Appl. Mater. Interfaces 6(14), 11448–11458., 
(2014)
[5] Tai, F. I. et al., Soft matter, 10(32), 5955–5964, (2014).

Minden érdeklődőt szeretettel várunk.

Bottyán László