hydrophobic hydrophilic
Post on 05-Mar-2016
241 Views
Preview:
DESCRIPTION
TRANSCRIPT
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 1/27
MANOJ KUMAR
III Semester
ME
Seminar on
HYDROPHOBIC AND HYDROPHILIC
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 2/27
• Some of the common natural
Hydrophobic materials are
a!es" oil and fats#
Hydrophobicity comes also from the $ree% ord Hydro&ater'
and (hobicity &fear' it refers to the physical property of amaterial that repels a mass of ater#
)HA* IS MEAN* H+,RO(HO-I.I*+ /
*he e0aluation of hydrophobicity
is made throu$h ater contact
an$le measurements#
A ater droplet ould be
spherical so the ater contact
an$le ill be si$nificantly hi$h#
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 3/27
• At the molecular le0el" the hydrophobic effect is important in
dri0in$ protein foldin$ formation of lipid bilayers and micelles"
insertion of membrane proteins into the nonpolar lipiden0ironment and protein1small molecule interactions# Substances
for hich this effect is obser0ed are %non as hydrophobes#
H+,RO(HO-I. E22E.*
*he hydrophobic effect represents the
tendency of ater to e!clude non1polar
molecules# *he effect ori$inates from
the disruption of hi$hly dynamic
hydro$en bonds beteen molecules of
li3uid ater#
.ontinued4#
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 4/27
SU(ER H+,RO(HO-I. .OA*IN5
Super hydrophobic technolo$y
ma%es ater bounce" it stops it"
rolls it off the surface#
*he process of coatin$ the surface of a material ith hydrophobic
property material in order to a0oid stic%in$ of li3uids on thatsurface#
*his is absolutely uni3ue ay of coatin$ unli%e con0entional hich
shrin% continuously durin$ dryin$ to produce lo porosity films#
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 5/27
+oun$6s e3uation is used to describe the interactions beteen
the forces of cohesion and adhesion and measure hat is
referred to as surface ener$y#
www.ramehart.com/contactangle.ht
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 6/27
• A drop ith a contact an$le o0er 789 is hydrophobic#
• *his condition is e!emplified by poor ettin$" pooradhesi0eness and the solid surface free ener$y is lo#
Continued..
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 7/27
Hydrophobic interactions
• Hydrophobic interactions describe the relations beteen ater and
hydrophobes &lo ater1soluble molecules'#
• Hydrophobes are nonpolar molecules and usually ha0e a lon$ chain
of carbons that do not interact ith ater molecules#
• *he mi!in$ of fat and ater is a $ood e!ample of this particularinteraction#
• *he common misconception is that ater and fat doesn:t mi! because
the ;an der )aals
•
forces that are actin$ upon both ater and fat molecules are too ea%#
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 8/27
.auses of Hydrophobic Interactions
• American chemist )alter Kau<mann disco0ered that nonpolarsubstances li%e fat molecules tend to clump up to$ether rather
that distributin$ itself in a ater medium" because this allo the
fat molecules to ha0e minimal contact ith ater#
Hdro!ho"ic
interaction# $Chem%i&i
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 9/27
2ormation of Hydrophobic Interactions
• *he mi!in$ hydrophobes and ater molecules is not spontaneous=
hoe0er" hydrophobic interactions beteen hydrophobes are spontaneous#
• )hen hydropobes come to$ether and interact ith each other" enthalpy
increases & is positi0e' because some of hydro$en bonds that form the
clathrate ca$e ill be bro%en#
• *earin$ don a portion of the clathrate ca$e ill cause the entropy to
increase & is positi0e'" since formin$ it decreases the entropy#
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 10/27
Accordin$ to the formula> ?5@ ?H1*?S
?H@Small positi0e 0alue
?S@ar$e positi0e 0alue
Result >?5@ Ne$ati0e
A ne$ati0e ?5 indicates that hydrophobic interactions are spontaneous
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 11/27
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 12/27
A((I.A*IONS
• A primary purpose of hydrophobic coatin$s such as polytetrafluoroethylene&(*2E'
or poly!ylylene is to act as a barrier a$ainst ater commonly seen in automobiles
• '#ed in (a"rication on metallic nano rod to !re)ent icing.
• It# i# widel u#ed in aero#!ace indu#tr (or !ro)iding anti$icing
coating on the #ur(ace o( the aero!lane .
• Hdro!ho"ic #el( cleaning gla##e# are in#talled in tra*c #en#orcontrol unit.
• %e induce hdro!ho"ic reco)er a(ter !la#ma treatment+ a!h#ical contact treatment ,PC- .
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 13/27
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 14/27
Hydrophilicity" also comes from the 5ree% ord Hydro &ater'
and (hilicity &friendship' it refers to a physical property of a
material that can transiently bond ith ater &HBO' throu$h
hydro$en bondin$# 2urthermore it allos the li3uid to enter the
pores of a material and totally et it#
)HA* IS MEAN* H+,RO(HII.I*+ /
• Almost all natural materials are
hydrophilic in nature#
*he e0aluation of hydrophilicity is
made throu$h ater contact an$le
measurements# A ater droplet
ould occupy as lon$ surface of the
hydrophilic material as possible# So
the ater contact an$le ill be
si$nificantly lo#
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 15/27
• *his is thermodynamically fa0orable" and ma%es these
molecules soluble not only in ater but also in other polar
sol0ents# *here are hydrophilic and hydrophobic parts of the
cell membrane#
• A hydrophilic molecule or portion of a molecule is one that is
typically char$e1polari<ed and capable of hydro$en bondin$"
enablin$ it to dissol0e more readily in ater than in oil orother hydrophobic sol0ents#
Hydrophilic coatin$s et the surface0ery easily" and maintain the etness for
lon$er time# *hus" usin$ hydrophilic
coatin$s eliminates the need for
additional lubricants#
H+,RO(HII. .OA*IN5
.ontinued4
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 16/27
Here +al#o we u#e #ame 0gure o( oung1#e2uation to e3!lain hdro!hilicit
A drop ith a small contact an$le
is hydrophilic#
*his condition reflects better
ettin$" better adhesi0eness" and
hi$her surface ener$y#
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 17/27
Hydrophilic Interactions
Interactions beteen ater and other molecules such that the
other molecules are attracted to ater are called hydrophilic
interactions#
Molecules that ha0e char$ed parts to them are attracted to the
char$es ithin the ater molecule#
*his is an important reason hy ater is such a $ood sol0ent
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 18/27
.ontinued4#
5lucose molecules ha0e polar hydro!yl&OH' $roups in them and
these attract the ater to them# )hen su$ar is in a crystal the
molecules are attracted to the ater and $o into solution#
Once in solution the molecules stay in solution at least in part
because they become surrounded by ater molecules# *his layer of
ater molecules surroundin$ another molecule is called a hydrationshell#
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 19/27
)hat does the stren$th of Hydrophilic Interactions depend on/
• Inhibitory effect mainly depended on their concentration and to a
lesser e!tent on the ion char$e and hydrated ion radii#
•
Ste!wi#e regre##ion anal#i# !ro)ed that the#trength o( interaction de!end# on the !olarit!arameter# o( amino acid# and i# inde!endent o(their chemical #tructure.
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 20/27
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 21/27
)en<el and .assie States of )ettin$
Here are to natural parameter>
A first natural and simple effect arisin$ from the presence of
microstructures is an increase of the surface area of the material#
r @CDBbhFpB
e can define to le0els= namely" the top of the posts and the $round
on hich they sit#
A second natural parameter is the ratio 6S beteen the top and
bottom surface areas" hich is also the post density#
ϕS @ bBFpB
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 22/27
)hen depositin$ a ater drop on a such solid #It can adopt atleast to type of confi$uration1
Quéré D , Reyssat M
Phil. Trans. R. Soc.
A 200!"##$%&"'(%&&#
conformin$ to the solid surface &%en7el #ituation'
Sittin$ on the top of the posts&,Ca##ie or (a&ir #tate'
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 23/27
www.me.umn.edu/8li3339::/;4RI<CA;S/Re#earch/te3turing.htm
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 24/27
*he Second and simplest picture is the so1called )en<el state
&fi$ure the drop Gust follos the structures on the material&)en<el C7'#
*his ill affect both the ettin$ &the 0alue of the e3uilibrium
an$le" that is the one hich minimi<es the surface ener$y of the
drop' and the adhesion &characteri<ed here by the 0alue of thecontact an$le hysteresis'#
cos@r cos
)en<el state
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 25/27
.assie state12a%ir state
*hird fi$# implies the creation of a li3uidL0apour interface belo the
drop" on a fraction of surface of the order of CϕS" considerin$ these
interfaces as flat &the drop is lar$e compared ith the pillars"
implyin$ a ne$li$ible cur0ature of the li3uidL0apour interface at the
scale of pillars'#
*he cosine of the apparent contact an$le is then an a0era$e beteenthe cosine of the +oun$ an$le and the cosine of C89" the an$le of a
ater drop on air" here the ei$hts for the a0era$e are" respecti0ely"
ϕS and CϕS#
cos@ 1C D s&CDcos'
&.assie P -a!ter C7QQ'
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 26/27
7/21/2019 Hydrophobic Hydrophilic
http://slidepdf.com/reader/full/hydrophobic-hydrophilic 27/27
-HAN=S
top related