A complete and permanent hydrophilic modiĩication of poly ethyleneterephthalate PET ĩilms is achieved by argon-plasma irradiation, subsequently graíting acrylic acid AA in vapor phase
Trang 1v w u JOURNÁL 0 F SCIENCE Nat., Sci., & Tech., T.XXIII, NọỊ, 2007
PLASMA-INDUCED GRAFT POLYMERIZATION OF ACRYLIC ACID
ONTO POLY(ETHYLENE TEREPHTHALATE) FILMS:
HYDROPHILIC MODIFICATION
Nguyen Kien Cuong
D e p a rtm e n t o fC h e m istry , College o f Science, V N U
ABSTRACT A complete and permanent hydrophilic modiĩication of poly
(ethyleneterephthalate) (PET) ĩilms is achieved by argon-plasma irradiation,
subsequently graíting acrylic acid (AA) in vapor phase onto their suríace Both Ar
plasma irradiation alone and post graíting AA rendered a complete hydrophilicity to
PET surtaces Hovvever, the hydrophilicity of the PET suríace, only treated with the
Ar plasma, is not permanent In contrast, PET íilms, irradiated by the Ar plasma,
exposed to air, and subsequently gratted with AA monomer, are permanently
hydrophilic Degradation of polymer chains on the plasma-irradiated surtace is
proportional to time of exposure Electron spectroscopy for chemical anaỉysis (ESCA)
coníirmed the grafting of AA onto the íilm suríace, whỉch results ỉn a large amount of
incorporated oxygen-containing íunctional groups like carboxylic (O ũ C' = O) and
carbonyl (C' = O) The morphology of graíted suríaces, observed by scanning
electron microscopy (SEM), displays some large area of microporosity compared to
relative smooth morphology of the control one Gratted íunctional groups and suríace
microporous structure are the main íactors to enhance hydrophilicity of the PET ĩilms
Keywords: Plasma-induced graft polymerization, polymer degradation, oxygen-
containing íunctional groups, hydrophilicity, microporosity and eiectron spectroscopy
ỉorchemical analysis (ESCA).
1 I n tr o d u c tio n
P o ly m eric m a te ria ls hold co n sid erab le in te re s t in th e íĩeld of b io m a te ria ls for
s c ie n tis ts in re c e n t y e a rs T issu e en g in ee rin g cu ltu re , m in im iz in g p ro te in ad so rp tio n to
p re v e n t m e m b ra n e -fo u lin g for p ro te in u ltra filtra tio n , im m o b iliza tio n of biologically
a c tiv e m olecules a n d liv in g cells, etc., a re r a th e r closely re la te d to h y d rophilic
c h a ra c te rs of p o ly m er su rfa c e s [1-3] S u rface h y d ro p h ilicity of th e polym er can be
a ch iev ed by th e in c o rp o ra tio n of oxygen-containing fu n c tio n a l gro u p s, su ch as — COOH
a n d — O H , w h ich a r e u s u a lly n o t coupled w ith m olecular c h a in s of th e po ly m er surface
S u ría c e m o d ificatio n s could e n h a n c e m echanical in te rlo ck in g , a n d c re a te fu n ctio n al gro u p s, im p ro v in g w e ttin g an d /o r chem ical bonding of a p o ly m er surface S y n th e tic
p o ly m ers, th e re fo re , o fte n re q u ire selective m o d iíĩcatio n s to in tro d u c e speciíìc
functional groups onto su ríaces for proper purposes, ex b inding of biom olecular, gas
b a rrie r, etc
T h e c o n v e n tio n a l m eth o d s (w et ch em istry ) for th e h y d ro p h ilic m odiíìcation of
p olym er s u ría c e s h a v e b e e n p erío rm ed by v ario u s ch em ical tre a tm e n ts , u su ally acco m p an ied by d a m a g in g polym er b u lk , h en ce affectin g its p ro p e rtie s In c o n tra s t to
47
Trang 24 8 N guyen Kien C uong
th e w et ch e m istry , th e polym er 8urface, exposed to p la s m a , c a n be m odiíĩed to e n h a n c e its hydrophilicity, c o m p a tib ility an d b io ĩu n ctio n ality M o reo v er, th e m odiíìed su rfa c e is,
in g en eral, coníìned to a to p -su rface la y e r less t h a n severa l h u n d r e d n a n o m e ters
th ro u g h p olym er th ic k n e ss T h e reío re, d e sira b le p r o p e rtie s of b u lk la y e rs a r e u s u a lly
m a in ta in e d H ow ever, on m o st polym er su rfaces, th e g a in e d h y d ro p h ilic ity is u s u a lly
n ot p e rm a n e n t, a n d d isa p p e a rs or d im in ish e s s ig n iíĩc a n tly a fte r o n ly p la sm a irra d ia tio n T h e irr a d ia te d su rface g ra d u a lly r e s to r e s its h y d ro p h o b ic ity d u e to
ừ a g m e n te d low -polym er c h a in s on 8urface lay ers, te n d in g to r e o r ie n t in to b u lk la y ers
T h is re su lte d in d e c re a se in a n u m b e r of fu n c tio n a l g ro u p s, th e re b y d e c re a sin g its
h y d ro p h ilicity P o st-g ra ft copolyraerization can fìx ra d ic a ls b y g ra ftin g a h y d ro p h ilic
m onom er onto th e ir r a d ia te d su ríac e , th e re fo re , r a is in g th e lifetim e o f su rface
h y d ro p h ilicity In a d d itio n , th e g ra ítin g of a speciíìc m o n o m er m a k e s a su rfac e m odified
w ith su ita b le ch em ical fu n c tio n a lity for b io m a te ria l a p p lic a tio n s [4-7]
In prev io u s p a p e r [8], h y d ro p h ilic im p ro v e m e n t of P E T ílb e rs in m o istu re
ab so rp tio n a n d d y ein g p e río rm a n c e h a s been re p o rte d A b so rp tio n e n h a n c e m e n t are
d u e to th e ex isten c e of carboxyl groups: 0 — c = o , in c o rp o ra te d on to P E T fĩber
su rĩa c e s, íu rth e rm o re , th e ccn d itio n s of th e p la s m a ir r a d ia tio n aa \vell a s g raít-
p o ly raerizatio n h a v e c o n sid e ra b ly eíTects on th e h y d ro p h ilic d u ra b ility of P E T fibers
T his p ap er describes PE T íìlm s, irra d ia te d w ith a m ix tu re of in e rt g a s e s like
h eliu m /arg o n (He/A r) a t p re ss u re of o n e -a tm o sp h e re , th e n s u b se q u e n tly graít- polym erized w ith acrylic acid in v ap o r to e n h a n c e th e ir s h y d ro p h ilic d u ra b ility over tim e EíTects of irra d ia tio n tim e on a w eigh loss ra tio a n d g r a ítin g d e g ree of P E T ’s film s
w ere in v e stig a te d O xy g en -co n tain in g fu n ctio n a l g ro u p s, c h a ra c te riz e d by electron spectroscopy for ch em ical a n a ly sis (ESCA), w ere u s e d to ro u g h ly e s tim a te hydrophilic
c ap ab ility of th e g ra fte d su rface S u rface m orphology of th e g ra fte d su rfa c e was observed by s c a n n in g ele c tro n m icroscopy (SEM) In ílu e n c e of th e g ra fte d íu n ctio n al
g ro u p s a n d su ría c e m orphology upon su rface h y d ro p h ilic ity w ill be d iscu ssed
2 E x p e rim e n ta l P r o c e d u re s
— C 3 ——
-2.1 Sam p le p rep a ra tio n
In P E T fílm s tr u c tu r e , two
groups of 0 — c = 0 bond,
sy ram etrically -b o n d ed to a n
a ro m a tic rin g , seem to be stab le
B esides, th e r e a re — C H 2 — C H 2
bonds \vith low er b o n d in g energy
H ence, th e d e g ra d a tio n of
m olecular c h a in s on its su rface
m ig h t occur a t c — H a n d c — c
m olecular bo n d s w h en th e
Ị \ » \ N e N_, R ị
1 1 1 1 1 * VH X g M*c
R # r a d l c a l s
c " I t o c t r o n i
© lon*
M * o l» c tr o n lc
e x c lte d p a r t id i
uv-mdlatlon
Substrate
e l o c t r o d ỡ
r f pow er
lúncdonal
groups
Fig.1 Principle o f plasma reaction insỉde electrodes
V N U J o u r n a ì o Ị S c ie n c e , N a i., S c i đc T e c h , TJOQỈỈ, N 0Ỉ , 20)7
Trang 3P lasm a - Induced graft poíym crization o f acrylic acid onto. 49
m o le c u la r c h a in ab so rb s p la sm a -e n e rg y from a c tiv a te d species a n d u ltra v io le t ray s
d u r in g th e p la sm a irra d ia tio n The prin cip le of p la sm a re a c tio n o cc u rrin g betw een two
e le c tro d e s is d escrib ed in íìg u re 1 Glow d isch a rg e p la sm a a t o n e -a tm o sp h ere w as
g e n e r a te d in a p la sm a re a c to r (m a n u ía c tu re d by P e a rl Kogyo Co L td , O sak a, J a p a n )
c o u p led w ith p a ra lle l p la te electrodes, w hich w ere covered by d ielectric b a rrie r-
c e ra m ic , a n d o p e ra tin g a t ra d io íreq u en cy of 13.56 M H z A P E T film sa m p le of 0.2 mm
i n th ic k n e ss, p ro v id ed by A sah i G lass F ib e rs Co L td (Ja p a n ), w as placed b etw een two ele c tro d e s, an d th e n irr a d ia te d w ith th e m ix tu re of H e/ A r in e r t g ases, in tro d u ce d by
th e c o n s ta n t flow r a te of 850m l /150m l m i n 1 (STP), a n d in tro d u c e d in to a p lasm a
c h a m b e r I r r a d ia te d from 10 sec to 3 m in, w ith p la sm a p o w e r-d e n sity of 1.75 w /c m 2, a t
e le c tro d e su ría c e te m p e r a tu re of a b o u t 70°c • 80°c, e a c h sa m p le w as rem oved from th e
p la sm a ch am b er, th e n im m e d ia tely w eig h ted to e s tim a te d e g ra d a tio n S tate of surface-
la y e rs T h e irr a d ia te d sa m p le vvas th e n g rafted w ith acrylic acid (AA) of 99.5% conc in
a g lass tu b e e v a c u a te d to 133 P a a t tw o level of c o n s ta n t te m p e ra tu re : 6 0 ° c a s w ell a s 70°C; th e g ra ftin g p rocess la s te d for 8 h o u rs a n d 1 h o u r, resp ectiv ely T a k e n from th e
g la ss tu b e , th e sa m p le w as e x tra c te d by h o t m e th a n o l in a S o x h let e x tra c to r for 2 h o u rs
to rem ove u n re a c te d re m a in in g m onom er an d hom opolym ers
2.2 ESCA c h a r a c te r iz a tio n o f m o d iíìed su rface
ESCA m e a s u re m e n t w as p erío rm ed on a K ra to s ESC A -3300 sp e c tro m e te r,
em p lo y in g M gK a (1253.6 eV) X -ray source T he e le c tro n ta k e -o ff a n g le w as a d ju ste d
a ro u n d 6 0 °c w ith re sp e c t to th e íìlm su ríac e T he p re s s u re in th e a n a ly s is c h a m b e r w as
m a in ta in e d a t a b o u t 1 0 5 P a du r in g th e d a ta ac q u isitio n T h e X -ray source w as ru n a t
th e an o d e v o ltag e of 8 kV a n d c u r re n t of 30 mA
2.3 S u rface m o rp h o lo g y ob served by SEM
S u ría c e m orphology o f th e g rafted íílm s w as o b serv ed by a sc a n n in g electron
m icroscope (SEM ), m odel J E O L JSM -5200 F o r b e tte r e le c tric con d u ctiv ity , a sa m p le ’s
su rface w as co ated w ith th in gold la y e r before th e e x a m in a tio n T h e o b serv atio n w as
p erío rm ed to d e te rm in e th e q u a lity of polym er d e p o sitio n s, a n d esp ecially to check
w h e th e r m icro p o res a p p e a r o n th e g ra fte d su rface
3 R e s u lts a n d D isc u ssio n
3.1 D e g r a d a tio n o f p lasm a-irrad iated su ría ce
T h e d e g ra d a tio n of th e film su ría c e ir r a d ia te d by p la sm a seem s to be
p re d o m in a n t effects of th e d isc h a rg e in te ra c tio n betvveen its su ría c e a n d a c tiv a te d species like ions, p a rtic le s, etc T h is process led to a n a lm o s t co rap lete b reak d o w n of c
— H o r c — c b o n d s, p ro d u cin g carb o n ra d ic a ls on ir r a d ia te đ su rfa c e s T h e polym er
d e g ra d a tio n can b e d escrib ed a s follows:
V N U J o u r n a l o f S c ie n c e N a t S ci.,& T e c h T X a i l N al , 2 0 0 7
Trang 450 Nguyen Kicn Cuoĩĩtg
II / ^ r \ 11 I I
o — c \ 0 ) — c — o — c — c
-H H
-Plasma
o - c - \ 0 / - c —o - c - c
W here: c • is a ra d ic a l g row n by th e d e g ra d a tio n of a m o le c u lar c h a in on th e P E T
su rface T h e p o ly m e r d e g ra d a tio n , c h a ra c te riz e d by w e ig h t-lo ss ra tio , w as c a lcu la ted in
th e follow ing ex p re ssio n :
W here: WL (%) is th e w e ig h t-lo ss ra tio ; W 0 a n d W] a re th e w e ig h t of a sa m p le
b eíore a n d a fte r th e G D P tr e a tm e n t T h e m in u s m a r k Ĩ8 d en o ted a s th e w e ig h t loss o f
th e m o lecu lar c h a in s d u e to th e d e g ra d a tio n
T h e d e g ra d a tio n of th e
m o lecu lar c h a in s on th e irr a d ia te d
su rface la y e rs v e rs u s th e tim e of
ex p o su re 18 in d ic a te d in th e Fig 2 I t
18 cle a rly t h a t th e w e ig h t lo ss ra tio ,
in d ic a tin g th e lev el of th e
d e g ra d a tio n , w e n t u p w ith f u r th e r
ex p o su re tim e L a rg e d isp e rsio n of
th e vveight loss is a s c rib e d to th e
effect of th e d e n s ity of a c tiv a te d
species, w h ich co llid ed w ith th e film
8urface a s w ell a s th e c ro ss-lin k in g
of ra d ic a ls g e n e ra te d on th e P E T
su rface d u rin g th e p la s m a
irra d ia tio n T h e s im ila r r e s u lts h a v e
also b ee n found in th e r e p o rt of
Y a su d a et. a ỉ.[9 ] E x p o sed to a ir,
th e se ra d ic a ls w e re r e a c te d w ith
oxygen in a ir to p ro d u c e p e ro x id e s a n d (— CO O H ) h y d ro p ero x id es T h e se peroxides,
b ein g in itia to rs for th e s u b s e q u e n t g ra ft p o ly m e riz a tio n w e re form ed a s following reactio n s:
Flg 2.
E xposure tim e (sec)
Degradation o f polym er surtace versus the tim e of irradiation
f o II o II H H ^ I I Exposuredto r o II o II H HiI I
II t r r \ 11
■ o - c - ( 0 ) - c — o — c — c - - -Air ■o—c (0/ c o c C rz\ II I
-V N U J o u r n a l o Ị S c ie n c e N a t Sci A T e c h T x a i l N 01 2 0 (7
Trang 5Plasm a - Induccd graft polym erization o f acrylic acid onto 51
3.2 E ữ e c ts o f th e e x p o su r e tlm e on g ra ftin g d e g r e e
O w ing to th e rm a lly -in d u c e d d e g ra d a tio n c o in c id e n t w ith th e p rese n c e of th e AA
m o n o m e r in v ap o r, c o • a n d • O H ra d ic a ls, decom posed from th e h y d ro p ero x id es, w ere
t h e n g raft- poly m erized in a g la ss tu b e , e v a c u a te d to 133 P a a t te m p e r a tu r e of 6 0 °c for
8 h rs a s w ell a s 7 0 °c for 1 h r G ra fte d w ith th e AA m o n o m e r of 99.5% conc., th e s e c o *
ra d ic a ls , in itia lly se rv in g a s a c tiv a te site s, re a c te d w ith th e m o n o m er to c re a te copolym ers w hile *OH ra d ic a ls, also re a c te d w ith th e s a m e m o n o m er, w ere ch an g ed
in to hom opolym ers
( o w o II H H , 1 Thermally r o o H H*1
II II 1 1
-■o—c-(0)—c —o—c —c- - - induced -—► - o—c-(0)— c —o —c —c-r —\ - + 'OH
II II I I
0 - C - ^ 0 ) - C —O - C — c
'O HJ
Acrylic acid
— >
Graýt
II /CT\ II
o - c - ( Q ) - c - o
Copolymers
H H
i 1
c - c - t
1 1
o
COOH
CH
ĩ
COOH
T h e w e tta b ility of th e g ra fte d
sam p le, reíle cted by g ra ftin g d eg ree,
w as c alc u la te d a s follows:
ơ (%) = 100 * (W2 ■ vv,) / Wl (2)
W here: Wj a n d W 2 a r e th e
sam p le’s w eig h t m e a s u re d b eío re a n d
aíler th e g raft polym erization, respectively
Fig 3 show s th e g ra ftin g d e g re e of
th e g ra ft p o ly m erized P E T fìlm su rface
as a fu n c tio n of th e e x p o su re tim e a t
d iííe re n t g ra ftin g te m p e r a tu re s T h e
h ig h e st g ra ftin g d e g re e w a s ach iev ed a t
30-sec o f th e ex p o su re tim e W ith f u rth e r
p lasm a irra d ia tio n , th e g r a ítin g d eg ree
g ra d u ally w e n t dow n, th e n lev eled OÍT a t
iọp
c
<s i
Õ
Exposure time (sec)
Fỉg 3 R elatỉonship between th e grattlng degree
& exposure tỉme o f the PET tilm suríace
V N U J o u r n a l o f S c ie n c e , N a t., Sci.,<í T e c h 'T J(XJỊỊ, N 0Ị , 2 0 0 7
Trang 652 Nguyen Kicn Cuong
over 90-sec H ence, th e lo n g er ừ ra d ia tio n tim e th a n 30-sec m ig h t c a u se u n fa v o ra b le etch in g , c ro ss-lin k in g a n d d e g ra d a tio n of th e P E T su ría c e , w hich re s u lte d in a no n e t
g ain of activ e sp ecies on th e irr a d ia te d su rface fo r s u b s e q u e n t g raft-p o ly m erized process
A lth o u g h th e p o ly m eriza tio n tim e d im in ish e d to 1 h o u r, th e h ig h e r g ra ftin g degree co in cid en t w ith th e h ig h e r a m o u n t of h o m o p o ly m ers w a s g ain ed a t g ra ftin g
te m p e ra tu re of 7 0 °c T h is can be a ssig n e d to a la rg e n u m b e r of decom posed rad icals, CO* a n d *OH, ow ing to th e th e rm a lly in d u ced d e g ra d a tio n , re a c te d w ith th e AA
m onom er T h e sa m e te n d e n c y of th e g ra ftin g d eg ree v e rsu s th e tim e of ex p o su re h as
also b een re p o rte d by Choi et al [10].
Fig 4 W ide-scan spectra o f a) the control surface & b) the suríace irradiated fo r 30-sec,
subsequently gratted at 70°c fo r 1 hour
3.3 ESCA ch a ra c te r iz a tio n
T h e ch em ical com positions of th e
P E T film su rface w ere a n a ly z e d by a n
ESCA tech n iq u e F ig u re 4 show s wide-
scan sp e c tra of a) th e co n tro l a n d b) th e
9urface irr a d ia te d for 30-sec subse-
q u e n tly g ra íte d a t 70°c for 1 ho u r
P e a k s of carb o n a n d oxygen b in d in g
en erg ies a r e lo cated a t 285 eV a n d 532
eV, respectively I t is n o te w o rth y t h a t
the relative suríace-atom ic concentrations
Surface chemical compbsitions ,%
Treatment c ,s 0 , s 0 IS/C ls
Unữeated 73.1 26.9 36.7 Graữed 67.3 32.7 48.6
Table 1 A tom ic com positions on the surface irradiated fo r 30-sec and subsequently gratted at
70°c fo r 1 hour
V N U J o u r n a l o f S c ie n c e , N a t Sci.,đc T e c h , T X O l l N o], 20Ơ
Trang 7Plasm a - Induced graft polym erizalion o f acrylic acỉd onto 53
o f oxygen a n d c a rb o n w ere sig n iíìcan tly a lte re d : th e C l s p eak of th e g ra fte d su rface is lovver th a n t h a t of th e control one vvhile O l s p eak of th e g ra fte d su ría c e is little h ig h e r
t h a n t h a t o f th e co n tro l su rface (Fig 4 & Tab 1) M oreover, th e ra tio , show n in
ta b le 1, w e n t u p from 36.7 % to 48.6 % for th e control a n d g ra fte d su ríac e , respectively
F u rth e rm o re th e oxygen c o n te n t rose from 26.9% to 32.7% c o rresp o n d in g to th e control
a n d g ra fte d 8urface, resp ectiv ely The co n sid erab le in c re a se in oxygen ato m ics ( 0 lg) is
a ssig n e d to a la rg e a m o u n t of oxygen-containing g ro u p s in c o rp o ra te d onto P E T g rafted
su rface F ig u re 5 sh o w s h ig h reso lu tio n scan s of th e c u core-level sp e c tra for th e
su rface, ir r a d ia te d fo r 30-sec su b se q u e n tly g ra ft-p o ly m erized a t 70°c for 1 h o u r a n d th e
co n tro l one
L in e -sh a p e a n a ly s is by th e deconvolution in d ic a te s t h a t th e c u sp e c tru m of th e
co n tro l su ría c e is com posed of th re e d istin c t p e ak s a t b in d in g en e rg y (BE) of 285.0, 286.5 a n d 289.1 eV, a ssig n e d to th e c*— H, c*— o (e.g., e th e r, e ste r) a n d 0 — c* = 0
(e.g., carboxylic acid, ester) groups, related to an aro m atic ring C6H 4—, CH2— CH2 —
o a n d CO — o g ro u p s, resp ectiv ely T h ese a s s ig n m e n ts a r e also in good a g re e m e n t
w ith th e s tr u c tu r e of a P E T re p e a tin g unit:
(— 0 — CO — C 6H< — c o — 0 — C H 2— C H 2—)„
o
*
& g g
o
Binding energy (eV)
Fig.5 Line-shape & high-resolution analysls o f the C1s peak spectra fo r (a) tha control surface and
(b) tha surtace irradiated fo r 30-sec subsequently gratted at 70°c fo r 1 hour
T h e re la tiv e ch e m ic a l compo- sitio n s of C i, s p e c tra on th e g ra te d su ría c e a re shown in ta b le 2 T h e re is a re la tiv e in c re a se in th e c o n te n t of 0 — c* = 0 carboxyỉ groups from 11.6 to 16.9% a n d th e c* = 0 carbonyl g ro u p is 9.4 % w h ile th e c o n te n t of
c * — H lin k a g e in th e a ro m a tic rin g and c * — 0 g ro u p s d e c re a se d from 67.5 to 56.6 % and from 20.9 to 17.1 %, respectively T h e se d a ta su g g e st t h a t th e graft-
polym erization m a in ly in volves in th e m odiíĩcation of — C6H 4 — a n d — c o — groups
Grafìed surface
XNU J o u r n a l o f S c ie n c e , N ư ĩ., S ci.,& T e c h , T.XXỈỊỈ, N 0Ị , 2 0 0 7
Trang 854 N guyen Kien Cuon g
Decomposition of the c t, peak
c „ component, % Treatment C*-H C*-0 0-C*=0 c*=0 Unừeated 67.5 20.9 11.6
Gratted 56.6 17.1 16.9 9.4
Table 2 Relative chem ical com positions o f c 1g spectra on the surtace ỉrradiated fo r 30-sec subsequently gratted at 70°c fo r 1 hour
M oreover, p o s t-p la sm a re a c tio n in a ir of
free ra d ic a ls, g e n e r a te d by b ro k en
m o lecu lar c h a in s a n d d e h y d ro g e n a tio n
m e c h a n ism s, led to th e íb rm a tio n of
carb o n y l fu n c tio n a l g ro u p s: c # = 0 a t
287.9 eV, a n ew lin k a g e from th e c* — o
group c re a te d by o x id a tio n p ro cesses
C learly, th e P E T su rfa c e w a s oxidized
due to a la rg e a m o u n t of oxygen-
c o n ta in in g íu n c tio n a l g ro u p s
in c o rp o ra te d on to th e P E T film su rfa c e T h e se fu n c tio n a l g ro u p s in c re a se h y d ro g en
bo n d in g force a n d th e su rfa c e free e n e rg y of th e film su rface H ence, h y d ro p h ilicity of
th e g ra íte d P E T su rfa c e w a s c o n sid e ra b ly e n h a n c e d
3.4 M o rp h o lo g ies o f PET film su rfa ce
F ig u re 6 sh o w s su rfa c e m o rp h o lo g ies of th e co n tro l a n d g ra íte d su ría c e s T he control s u rfa c e (Fig
6, left) looks lik e
sm ooth w h ile th e
m odiíied one (Fig 6,
rig h t) seem s to be
rough w ith r e g u la r
c o rn -s tru c tu re T h e
m orphological
d istin c tio n is
a ttrib u te d to th e
ừ a g m e n ta tio n of
polym er c h a in s
c a u se d by th e
su rface e tc h in g , a n d to
g ra ítin g AA m o n o m e r
onto th e ra d ic a ls, de-
com posed from th e
h y d ro p ero x id es I t is a s s u m e d t h a t th e ro u g h e d s u ría c e is one of m a in facto rs th a t
e n h a n c e h y d ro p h ilic ity of th e P E T su rfa c e
4 C o n c lu s io n s
P la s m a -in d u c e d g ra ft-p o ly m e riz a tio n of ac ry lic acid on to the poly(ethylene terephthalate) (P E T ) íìlm su rfa c e sig n iíìc a n tly im p ro v e d its h y d ro p h ilicity T h e PET
su rface, ir r a d ia te d for 30-sec a n d s u b s e q u e n tly g ra fte d w ith th e AA m onom er a t 70°c, show s th e h ig h e s t g ra ftin g d eg ree T h e c h a r a c te r iz a tio n of th e g ra íte d su rface c le a rlv
Fỉg.6 SEM m ỉcrographs o f the film surtace ỉrradiated fo r 30-sec subsequently gratted at 70°c ío r 1 hour, (lett) the control surtace,
and (rỉght) the grafted one
V N U J o u r n a l o f S c ie n c e N a i S c i,& T e c h T XXIỉì N 0Ì 2 0 0 7
Trang 9Plasm a - Induccd graft polym crization o f acrylic acid o nto 55
c o n íirm e d th e la rg e a m o u n t of o x y g e n -c o n tain in g íu n c tio n a l g ro u p s w e re in c o rp o ra te d
o n to th e P E T film in th e form of o — c* = 0 a n d ơ = o , b e in g th e c le a r in d ic a tio n of
th e h y d ro p h ilic su rfa c e S h o w n by SEM m ic ro g ra p h s , film s u ría c e s , g ra íte d by copolym ers, show th e ir su rfa c e m orphology lik e th e r e g u la r c o rn -su rfa c e t h a t is clear
ev id en ce in m icro p o ro u s s tr u c tu r e T h is s u g g e sts t h a t h y d ro p h ilic e n h a n c e m e n t is closely re la te d to o x y g e n -íu n c tio n a l g ro u p s in c o rp o ra te d o n to th e P E T s u rĩa c e a n d its
m icroporous m orphology
A ck n ovvled gem en ts
T h e re s e a rc h w ork w as a p a r t of th e N a tio n a l R e s e a rc h P ro jec t, g r a n te d by New
E n e rg y & D ev e lo p m e n t O rg a n iz a tio n (N ED O ), a n d c a r rie d o u t a t D e p a rtm e n t of
O rg an ic M a te ria ls , A d v an ced I n s titu te of S cience & T ech n o lo g y (A IS T )-K ansai, ơ a p a n (1998-2000) T h e a u th o r g ra te fu lly acknovvledges th e O s a k a S cience & Technology
C e n te r (O STEC), J a p a n for avvarding th e p o std o c to ra l fe llo w sh ip a n d re se a rc h g ra n t
S pecial th a n k s a r e also d u e to D r S eiich i K a ta o k a , a íb rm e r s c ie n tis t of th e O rg an ic
M a te ria ls D e p a rtm e n t, A IS T -K a n sa i, J a p a n for h is u se fu l d isc u ssio n on th e e x p e rim e n t
of th e g ra ft-p o ly m e riz a tio n F in a lly , th is w ork did n o t w ell r u n if w ith o u t th e s u p p o rt of Prof S u su m u Y o sh id a, fo rm e r D e a n of O rg a n ic M a te r ia ls D e p t., A IS T -K an sai, a t
p re se n t, vvorking a t I n s titu te of A d v an ced E n e rg y (IA E), K yoto U n iv e rsity , J a p a n
REFERENCES
1 J.H Lee, H w J u n g , I.K K ang & H.B Lee: C ell b e h a v io r on p o ly m er su ría c e s w ith
d iffere n t íu n c tio n a l g ro u p s Biomaterials, 15 (1994) 705-711.
2 Y Ik ad a: S u ría c e m o d iíĩc atio n of po ly m ers for m edical a p p lic a tio n s Biomaterials, 15 (1Ồ94)
725 736.
3 P.B VVachem, T Beugeling, J Feijen, A B antjest J p Detm ers & w G van Aken:
In te ra c tio n of c u ltu re d h u m a n e n d o th e lia l cells w ith p olym eric s u ría c e s of d ifferent
w e tta b ility Bỉomaterials, 6(1985) 403-408.
4 c Wang: Oxidation of polyethylene surface by glow discharge & subsequent graft
copolymerization of acid acrylic J Appl Polym Sci., Polym Chem E d 31 (1993) 1307.
5 D s W av h al & E.R F ish e r: H ydrop hilic m o d iíĩcatio n o f p>olyethersulfone m e m b ra n e s by
low tem perature plasma-induced ^raft polymerization J Membr S ci.t 209 (2002) 255-269.
6 M M ori, Y U y am a & Y Ik a d a : S u rĩa c e m o d ificatio n of p o ly e th y len e fib er by g ra ft
p o ly m erizatio n J polym Sci.Polym Chem., 32 (1994) 1683.
7 I.K K ang, I.K K ang, O H Kwon, Y.M Lee & Y.K S u ng : P re p a ra tio n & su ríace
c h a ra c te riz a tio n of íu n c tio n a l group*grafted a n d h e p a rin -im m o b iliz e đ p o ly u re th a n e s by
p la sm a glow d isch arg e Bỉomaterials, 17 (1996) 841*847.
8 N.K Cuong, N Saeki, s Kataoka & s Yoshikawa: Hydrophilic im provem ent of PET fíber
using plasm a-induced graft polymerization at atm ospheric pressure Hyomen Kagaku,
ơournal o fS u r fa c e Science Society, Japan> Vol 23, No 4 (2002) 202-208.
vvơ J o u r n a l o f S c ie n c e N a i S c i.,á T e c h , T X Q i ỉ , N 0Ì 2 0 0 7
Trang 1056 N guyen Kien Cu ong’.
9 H Y a s u d a : P la s m a Polymerization. A c a d e m ic P r e s s , N e w Y o rk , 1985.
10 H.s Choi, Y.s Kim, Y Zhang, s, Tang, s.w Myung & B.c Shin; Plasm a-induced g raft
copolymerization of acrylic acid onto the polyurethane suríace Surface & Coating
TẠP CHÍ KHOA HỌC DHQGHN KHTN & CN, T.XX1IỈ, Số 1, 2007
TRÙNG HỢP & CẤY GHÉP AXÍT ACRYLIC VÀO BỂ MẶT PHIM POLY(ETHYLENE TEREPHTHALATE) BANG PLASMA: b i ế n t í n h
THẤM ƯỚT
N guyễn Kiên Cường
Khoa Hóa học, Đại học Khoa học Tự Nhiên, ĐHQGHN
B iến tín h th â m ướt củ a p o ly(eth ylen eterep h th a la te) (P E T) p h im , ổn đ ịn h th e o th ò i
g ian, có th ể được th ự c h iệ n b ằ n g p h ư ơ n g p h á p ch iếu x ạ k h í a g o n -p lasm a , v à trù n g hợp ghép vói hơi a x ít acrylic (AA) c ả h a i p h ư ơ n g p h á p c h iếu x ạ p la sm a và t r ù n g hợp ghép
AA m onom e đ ều tă n g k h ả n ă n g th ấ m ư ốt củ a bề m ặ t P E T p h im T u y n h iê n n ếu xử lý
bể m ặ t P E T b ằ n g các p hư ơng p h á p trê n n h ư n g riê n g rẽ, th i tín h th ấ m ư ó t củ a P E T phim bị su y giảm th e o thờ i gian T ro n g k h i đó k ế t hợp c ả h a i p hư ơng p h á p xử lý trê n sẽ cho phép P E T p h im d uy tr ì tín h th ấ m ướt th e o thời g ian K ế t q ủ a n g h iê n cứ u đ ã chỉ ra
rằ n g sự p h â n rả củ a các chuỗi p h â n tử lớp bể m ặ t po ly m e tỷ lệ th u ậ n vối thời g ian chiếu xạ P h ổ ESCA đã cho th â y sự g h é p -trù n g hợp c ủ a AA m onom e đ ã cho m ột sô' lượng lớn các nhóm chức như : ( 0 — c* = 0 ) carboxylic & (C* = O) carb o n y l, được cấy ghép vào b ể m ặ t P E T phim H ìn h th á i bề m ặ t của b ề m ặ t P E T p h im được xử lý là m àn g copolym e có độ d ày vài tră m n a n o m é t, có đặc tín h th ấ m ướt, có c ấu trú c lỗ xốp và liên
k ế t h o á học với lốp P E T n ền Đ iều đó có th ể q u a n s á t b ằ n g k ín h h iể n vi đ iệ n tử q u é t (SEM) G h é p -trù n g hợp các nhóm chức v à cấu trú c lỗ xốp củ a b ề m ặ t p h im sa u k h i xử
lý là n h ữ n g n h â n tố c h ín h đ ể tă n g k h ả n ă n g th ấ m ướt c ủ a P E T phim
T ừ k h o á : T rừ n g hợp g h ép b ằ n g chiếu xạ p la s m a , đ ứ t m ạ ch chu ỗi p o lym e, nhóm chức, tín h th ấ m ướt, vi lỗ & p h ổ tia X cho p h â n tích hoá học (ESC A ).
V N U J o u n i a l o f S c ie n c e N a i S c i i T e c h T.XXIII N 0I, 2 0 0 :