TOM 4 lipiec-sierpień 2000 r. S ia a tw t& iy nr 4
B o g u m iła M a s iu la n is * , J o a n n a B r z e sk a * , A g n ie s z k a T ercjak *
Polyurethane elastomers from cycloaliphatic diisocyanate and polyols with participation of ca
stor oil
In order to obtain the elastomers useful fo r medicine, the polyurethanes (PURs) with 4 ,4 ’-m ethylenedicyclohexyl diisocyanate and castor oil participation were obtained in the presence o f different catalysts.These PURs are o f good mechanical properties and good chemical resistance to hot water and hexane. In sorption o f water and contact angle with water the obtained PURs are close to some typical ‘’biomedical” polyurethanes but there was found greater sorption o f natural oil in these elastomers. The thermomechanical
and thermochemical properties o f PURs were described.
Key words: polyurethanes, castor oil, physical and chemical properties
Elastom ery ufetanowe z cykloalifatycznego diizocyjanianu i polioli z udziałem oleju rycynowego
W celu uzyskania elastomerów przydatnych dla medycyny dokonano syntezy poliuretanów (PUR) z udziałem 4 ,4 ’-diizocyjanianu dicykloheksylometanu i oleju rycynowego, w obecności różnych katalizatorów.
Otrzymane PUR charakteryzowały się dobrymi właściwościami mechanicznymi i dobrą odpornością chemiczną na działanie gorącej wody i heksanu. Pod względem sorpcji wody i kąta zwilżania otrzymane elastomery są podobne do typowych poliuretanów *’biomedycznych”, natomiast wykazują zwiększoną sorpcję oleju naturalnego. Opisano sta b iln o ść term om echaniczną i termochemiczną otrzymanych elastomerów uretanowych.
Słowa kluczowe: poliuretany, olej rycynowy, właściwości fizyczne i chemiczne
‘Technical University of Gdańsk, Dptm. of Polymer Technology, Gdańsk, Poland
S h to to rtterity nr 4 lipiec-sierpień 2000 r. TOM 4
We expected that use of the castor oil in PUR synthesis would allow hemocompatibility because of the expected greater affinity to albumins, counterac
ting the deposition of thrombogenic fibrinogen. The PUR with incorporated natural lipid substance would be more close to the natural cell membrane, built from proteins and fats. The partial crosslinking of PURs and their intrinsic plasticization connected with the I struc
ture should have an advantageous effect on the flexi
bility of the PURs. It was interesting if such obtained elastomers fulfil requirements of materials for medi
cine with regard to physical and chemical properties.
Experimental
M aterials
The substrates used in PUR synthesis:
• Poly(oxytetramethylene) glycols (PTMG): Teratha- ne 2000, (Du Pont, Aldrich), M=2040 g/mol, and PTMG M= 1000 g/mol, (Du Pont); before synthe
sis the melts of PTMG were filtrated and dehydra
ted by heating at mixing at 90°C under reduced pres
sure (1.4 hPa) through 3 h.
• 4,4’-Methylene dicyclohexyl diisoćyanate (SMDI), (Aldrich), mixture of isomers; distilled under re
duced pressure at temp. 200°C.
• 1,4-Butanediol (1,4-BD) (BASF), dehydrated and purified by azeotropic distillation.
• Castor oil (C.O.), (Aldrich), dehydrated by heating in vacuum rotatory (1.4 hPa) at 60°C/3 h; the estimated Loh=177 mg KOH/g, LCOOH=5.48 mgKOH/g.
• Catalysts;
- Dibutyltindioctoate (DBTDO), (Air Chemicals);
- Stannous 2-ethylhexanoate (stannous octoate, SnOc), (Sigma);
- Diazabicyclooctane (tri-ethyleiiediamine) (DAB- CO), (Houdry-Huls).
• Solvent - dimethylformamide (DMF) (POCh Po
land), dehydrated over P20 5 and distilled under re
duced pressure.
Synthesis o f PURs
PUR-I based on PTMG 1000 and PUR II-V ba
sed oh PTMG 2040 were obtained by two step me
thod with the equivalent ratio of NCO to OH groups with different contents of the substrates and catalysts (Table 1). In the first step the prepolymer from PTMG,
Introduction
The polyurethane elastomers (PUR) are nowa
days one from the best polymeric materials used in medicine for implantation and blood contact applica
tions. This is connected with very good mechanical properties of PURs, the possibility to vary widely the hardness and elasticity properties and, simultaneously, ensuring good ‘’biocompatibility”. The last property of PURs is attributed now to the segmented structure of these polymers, separation of the immiscible hard and soft segments and, as a consequence, hydrophi
lic-hydrophobic balance on the surfaces of polyure
thane jnaterials [1,2].
PURs are used for such important medical wa
res as synthetic vascular grafts, intraaortic balloons, left ventricular assist pumps, catheters, heart valves and total artificial hearts [1-4]. Nevertheless, the anxie
ty to diminish thrombogenicity and to improve stabili
ty of PUR in long-term contact with living tissue is still the aim of many researches [5,6].
One of the methods used to enhance biocompa
tibility is to increase the affinity of polymeric mate
rials to albumins. It was stated that albumin coated surfaces indicate diminished blood coagulation as well as diminished adherence, of bacteria [7].
In the living cells, albumins are bound in com
plexes with fatty acids. Binding of albumins to long aliphatic chains in polymeric structures was the reason of their good compatibility with blood as was found for some PURs [8,9].
In our previous paper we described synthesis and properties of the poly(urethaneureas) containing he- xadecyl side chains which exhibited good hemocom- patibility and very low change of the total activity of blood proteins [10].
In this paper we present the synthesis and some physical and chemical properties of PURs obtained with participation of the castor oil (C.O.) as a polyol reagent, besides other typical substrates in synthesis of such polymers.
The main ingredient of C.O., the natural, rene
wable fat resource, is the tri-glyceride of the 12-hy
droxy oleic acid (ricinoleic acid) (I) [11]:
TOM 4 lipiec-sierpień 2000 r. £,Ca6tó4H&ity nr 4
C.O. and diisocyanate was obtained at temp. 90-95°C under reduced pressure (1,4 hPa) in a presence of the catalyst with mass % shown in Table 1. After cooling the prepolymer to 60°C the DMF was added (to solid mass concentration of 30-50%), and in the second step the reaction with 1,4-BD was followed under normal pressure through 2 h at temp. 60°C. The reaction was controlled by IR spectroscopy, after evaporation of the solvent from the polymer films on NąCl.
Table 1. R a tio o f poliolshydroxyl g ro u p s a n d c a ta ly s ts in s y n th e s is o f P U R - I fromPTMG 1 0 0 0 a n d P U R
I I - V fr o m P T M G 2 0 4 0
Tabela 1. S to su n e k g r u p h y d ro k sy lo w y c h p o lio li i u d zia ł
k a ta liz a to r a w s y n te z a c h P U 1 0 0 0 i P U R I I - I V z P T M G 2 0 4 0
Stoichiometric ratio of
PUR OH groups Catalysts, mass %
P ilili PTMG Castor oil 1 ,4-BD •
1 1 0.2 2 DBTD0 (0.04)
II 1 0.3 3.5 DBTD0 (0.04)
III 1 0.3 3.5 SnOc (0.09)
IV 1 0.73 4.72 SnOc (0.09)
V 1 0.73 4.72 DABC0 (2.5)
PURs were processed into foils by pouring the polymer solution into a centrifuge aluminium drum, covered by silicon antiadhesion layer, and evapora
tion of the solvent at temp, up to 60-70°C. Polymer layer was gradually heated in vacuum dryer (1,4 hPa) to temp. 80°C/1 h and next to tem p.ll0°C/5 h. PUR foils were finally heated in vacuum dryer for 3 h at 140°C.
Before the investigations of properties the PUR foils were seasoned for 7 days at room temperature.
Methods o f investigation
Mechanical properties
The stress-strain properties of PURs were tested at room temperature with the tensile tester FPZ 100 (Rauenstein, Germany), using samples of 50 mm x 10 mm in dimensions and thickness of 0.1 to 0.2 mm, at the extension rate of 4.5 mm/s.
The hardness was determined with Shoffe’s A apparatus on samples consisting of several layers of PUR foils (approximate value).
The flexibility of PURs was measured with use
of de Mattia apparatus, according to PN-69/C-94170 with a frequency of 300±10 cycles/min; the samples of foils of 140x25 mm in dimensions and 0.1-0.3 mm in thickness were used.
fhermomechanicaland thermochemical analyses The dynam ic m echanical therm al analysis (DMTA) in the temperature range from -100°C to 200°C was carried out on Polymer Laboratory DMTA Mk III analyser (England), at a heating rate of 4 deg/
min and at a frequency of 1 Hz.
The thermogravimetric analysis (TG) and diffe
rential thermal analysis (DTA) were performed in air by means of the OD 104 MOM Derivatograph (Hun
gary), at the heating rate of 6 deg/min and sensitivity of TG-200, DTG-1/5 and DTA-1/3.
Stability o f PURs in contact with water, hexane and natural oil
The properties of PURs in contact with water and oil were performed on samples of foils washed before with water containing detergent, water from mains and distilled water. After drying foils were extracted by hexane in Soxhlet apparatus for 5 h. Foils were next dried for five or more days at room temperature.
The changes of surface view were investigated after this cleaning process with use of the optic reflec
ted microscope of PZO, Warsaw, with the objective 20/0.6 and the camera of Videotronic International GmbH; the magnification - 300x.
The samples of PUR foils with both sides surfa
ces of 120 cm2 were treated by 20 cm3 of redistilled water at temp. 70°C/24 h. pH of the water extracts was m easured at room tem perature with the CP-215 pH-meter (Elmetron, Poland). Such obtained water extracts from PURs were evaporated and their dry re
sidues were compared with a dry residue of the same volume redistilled water. This investigation was made according to USP XXII, Physicochemical Tests-Pla- stics.
According to procedure outlined in Code of Fe
deral Regulation,Title 21, Ch. 1, Subchapter B, part 177.2600 [12], the extracts from PURs in boiling wa
ter and in boiling hexane were obtained (at refluxing) for 7 h and additionaly 2 h. Dry residues of the extracts were determined and investigated by IR spectroscopy, by means of the Specord 71 IR (Carl Zeiss, Jena) - films on NaCI or by means of Bruker IR spectropho
tometer - in KBr.
Sessile drop contact angles with water in air were
S fa & b w t& iy nr 4 lipiec-sierpień 2000 r. TOM 4
measured using a goniometer, at room temperature.
Water sorption and sunflower oil sorption were determined with an accuracy, of O.OOOlg by measu
ring the increase of weight of dried PUR samples after keeping them in distilled water or in oil at temp. 38°C/
24 h. Samples of foils were after sorption pressed be
tween filter paper and immediately weighed.
Results and discussion
In the Table 1 the polyol components and cataly
sts used in PURs synthesis is presented and on the Fig. 1 the scheme of their chemical structure is shown.
The IR spectrum of PUR - II on the Fig. 2 measured after synthesis and drying the film on NaCI (0.5 h/50°/
1.4 hPa) shows the bands: NH at 3200 cm*1, CH2 at 2860 cm-1, 2795 cm '1 and 1450 cm '1 (in cyclohexane ring), C=0 at 1703 cm '1 in urethane group: and 1690 cm '1 in ester group, N-H + C-N at 1530 cm '1, C-O-C in ester group at 1250 cm '1, CH2-0-CH2 in polyether chain at 1110 c m 1; the bands at 1675 cm '1 and 980 cm'
‘are due to C=C band.
Beside of typical substrates e.g. polyetherdiol - PTMG and 1,4-BD as a chain extender of PUR ma
cromolecules, we used in syntheses the castor oil and SMDI. The means of the cycloaliphatic diisocyanate allow to eliminate the possibility of occurrence of the toxic, carcinogenic aromatic p,p’-diamine, which may occur through hydrolysis in PUR obtained from 4,4’-me- thylenediphenylmethane diisocyanate (MDI). SMDI is now used in producing of some commercial polyuretha-.
ne elastomers for medical applications [1-5].
The advantageous feature of such elastomers is also the low temperature of processability and the lack of yellowing in comparison to polyurethanes from the aromatic MDI, in which the quinoid structure is for
med on the light [13].
M echanical properties o f PURs
PURs I-IV obtained in our work are similar in hardness and tensile strength (Table 2) to such com
mercial ‘’biom edical” polyurethanes as Pellethane 2363 - 8 0 A (Dow Chemical)[12] or ChronoThane P -
Fig. 1. S c h e m e o f th e c h e m ic a l s tr u c tu r e P U R s Rys. 1. S c h e m a t s tr u k tu r y c h e m ic z n e j o tr z y m a n y c h P U R
Fig. 2. IR s p e c tr u m o f th e P U R - II (film o f N a C l )
Rys. 2. W idm o a b s o r p c y jn e w p o d c z e r w ie n i P U R - II (film n a N a C l)
75A (CardioTech International)[14] (Table 3) produ
ced from MDI, PTMG and 1,4-BD and also to elasto
mers manufactured from SMDI as Tecoflex - 80A (Thermedics Inc.)[3,5] and ChronoFlex AL - 80A (Car
dioTech International), the last one manufactured from polycarbonatediol[14] (Table 3).
The PUR - V synthesised with use of tert-amine catalyst DABCO is characterized by lower tensile strength than remaining PURs, obtained with organic tin compounds presence. From these last catalysts, the DBTDO was more active in syntheses than SnOc, which concentration necessary to obtain elastomers of
Table 2. M e c h a n ic a l p r o p e r tie s o f o b ta in e d P U R s Tabela 2. W ła ś c iw o ś c i m e c h a n ic z n e o tr z y m a n y c h
PUR
Hardness,
°SliA
Stress at 100%
elongation, a 300, MPa
Stress at 300%
elongation, c 30b, MPa
Tensile strength a„, MPa
Ultimate elongation eb,
%
Tension set,
%
1 82 7.1 27.5 41.4 370 4
II 82 8.2 17.2 49.5 550 10
III 82 6.8 14.5 34.8 530 13
IV 83 8.8 17.1 31.0 500 18
V 81 6.8 13.5 18.6 430 14
S fa a fo n t& U f, nr 4 lipiec-sierpień 2000 r. TOM 4
Table 3. Mechanical properties o f some commercial “biomedical” polyurethanes
Tabela 3. Właściwości mechaniczne wybranych handlowych poliuretanów “biomedycznych”
Polyurethane Hardness,
°ShA
Stress at 100%
elongation, c 100, MPa
Stress at 300%
elongation, c 300, MPa
Tensile strength a„,
MPa
Ultimate elongation eb,
%
References
Pellethane 2363-80A 83 5.86 10.0 41.4 550 12
ChronoThane P-75A 75 5.80 11.4 35.2 800 14
Tecoflex 80A 85 2.8* 6.7 42.0 580 2,3
ChronoFlex AL 80 4.5 - 36.5 585 14
* Initial modulus
good m echanical properties had to be more than twice greater. The advantageous property of SnOc catalyst is its low toxicity [15]; according to the producers (f.e.
Akzo Chem ie) this catalyst is harm less.
In c o m p ariso n to co m m ercial ‘’b io m e d ic a l”
poly ureth anes the PU R s obtain ed in our w ork w ith C.O. participation are characterized by greater stress at 100% and 300% o f elo n g atio n ( a l00, c 300) m e
asured at ro om tem p eratu re. It m ay be changed to low er values by d ecrease o f the 1,4-BD and SM D I ratio in p o ly m e r syn th esis.
PU R - I from P T M G 1000 is m ore stiff than elasto m ers o b tain ed from P T M G 2040, as indicate the m uch h ig h er c 3(X)and lo w er e b (Table 2).
We com p ared also the PU R s II - IV w ith p o ly urethanes d escrib ed by S ax en a and c o w o rk e rs[16]
and w ith P U R o b tain ed in an o th er way in -our la- boratory[17] fro m p oly (ox y pro py len e)g ly col, M D I, 1,4-BD and C .O .T h e elasto m ers presen ted in this paper are o f d istin ctly h ig h er ten sile strength.
In v estig atio n o f resistan ce to m ultiple bending on de M attia fle x o m ete r show n th at the PU R - II, III and IV w ith stan d w ith o u t fatig u e failure o ver 23 912 000 cycles. F o r the T ecoflex 80A the fati
gue cycles o f 2 x l 0 6 and fo r P ellethan e 2363 - 80A the fatigu e cy cles o f 2 3 x 1 0 6 w as m entioned [3],
Therm om echanical a n d therm ochem i
cal stability o f obtain ed PURs
On the Fig. 3 the dynam ic m echanical therm al analysis diag ram is show n for PUR-IV. The av era
ge glass tem p eratu res (Tg), the softening tem pera
tures (Tml, T m2) and the storage m oduli o f elasticity (E ’) in three tem p eratu res are describ ed in the Ta
ble 4 for PU R I-IV.
The glass tem p eratu res assign ed from the m a
xim um o f the loss m oduli (E ”) w ere show n for all
PU Rs near tem p. -57°C (Table 4). On the tan8 = E ’VE’ tem perature dependence, beside of the m a
xim um resp o n sib le for T g, a second m axim um was v isible for all PU R s at tem p. 36-50°C connected probably w ith the change in the hard segm ents of sm all range o f arrangem ent. This conversion in phy
sical stru ctu re o f ob tain ed PU R and th eir partial softening at body tem p eratu re, was noted also on decrease o f the E ’ m oduli w ith increasing the tem perature to 40°C, p articu larly great for PU R -I from PTM G 1000 (Table 4). The PU R s from PTM G 2040 even at tem p. 100°C ex h ib it the elastic m oduli at bending o f sig n ifican t value.
Table 4. Thermomechanical properties o f PURs (from DMT A with bending)
Tabela 4. Właściwości termomechaniczne PUR (na podstawie DMTA przy zginaniu)
Storage moduli of elasticity, E', MPa
PUR T , °C ---:--- Tm1,«C Tm2,»c at 25°C at 40°C at100°C
1 -57 156.4 37.2 4.9 36 163
II -57 120.0 103.0 29.8 42 132
III -56 267.0 182.0 42.0 - 134
IV -57 316.0 214.0 29.0 44 150
The very strong d eflectio ns of tan8 tem pera
ture dependence up to 126-150°C for PUR II-IV and up to 160°C for PU R -I corresp on ds to full so fte
ning and flow of these elasto m ers (T m2) (Table 4).
On the DTA plots for PU R I-IV we observed an endotherm ic pick in the range of 170°C - 177°C (Table 5), which may be connected with melting tem perature of the segments from SMDI and 1,4-BD.
F ro m th e th e rm o g ra v im e tric a n a ly sis (TG , D TG ) the tem p eratu res o f the decom position start resp on sib le for 10% w eight loss (T 10) o f PU Rs were d e term in ed at 322-336°C . N ext tw o steps o f the
TOM 4 lipiec-sierpień 2000 r. S C a a tw t& ity nr 4
Fig. 3. The tem perature dependences o f the dynam ic storage ( E ’) a n d loss (E ”) m oduli o f elasticity an d ta n S fo r PUR-TV Rys. 3. Z a le ż n o ś c i te m p e r a tu r o w e d y n a m ic z n y c h m o d u łó w s p r ę ż y s to ś c i z a c h o w a w c z e g o ( E ’) i s tr a t- n o ś c i ( E ”) o r a z t g S d l a P U R - I V
maximal thermal decom position were visible (T lmax, T2max); at temp. 400°C the mass residue of obtained PURs was in the range of 65-68% (Table 5).
Table 5. T h e rm a l sta b ility o f P U R s (fr o m D T A a n d T G ) Tabela 5. S ta b iln o ś ć te r m ic z n a P U R (n a p o d s ta w ie D T A i T G )
PUR "^melt5
oC To-
“C Tmax*
°c
Tmax:
°c
Mass residue at 400°C, %
1 174 336 354 420 65
II 177 336 347 428 68
III 170 327 332 428 64
IV 174 322 333 434 65
Investigation o f the interaction PUR with water, hexane and natural oil
The microscopic observations of the PURs sur
faces showed that the cleaning of these polymers by water with detergent did not cause greater changes on the foil surfaces, but after the extractions by hexane in Soxhlet apparatus the view of the foils surface was more extended (Fig. 4).
The sessile drop contact angles with water were measured from 72° for PUR -II to 81° for PUR-I (Ta
ble 6). The lower hydrophilicity of PURs obtained with C.O. participation caused lower water sorption in the
se polymers (Table 6) than was found for such ‘’bio
medical” polyurethanes as polyurethane-polysiloxane Cardiothane 51 or poly(urethaneurea) Biomer Sol G, to which sorption of water was given 1.6% and 1.2%
responsible [3].
Table 6. P r o p e r tie s o f P U R s in c o n ta c t w ith w a te r Tabela 6. W ła ś c iw o ś c i P U R p o d d a n e g o o d d z ia ły w a n iu w o d y
PUR
Sessile contact angles,0
Sorption of water Am/m, %
Extractes in water past 24 h/70°C pH pH displacement
I 81 0.1 4.95 1.84
II 72 0.7 5.15 1.64
III 79 0.8 5.76 1.03
IV 80 0.86 5.55 1.24
S tftłtM te fity nr 4 lipiec-sierpień 2000 r. TOM 4
Fig. 4. T h e m ic r o s c o p ic im a g e o f th e P U R - II su rfa c e : a) raw; b ) a fte r w a s h in g b y w a te r w ith d e te r g e n t, c) a fte r e x tra c tio n w ith h e x a n e in S o x h le t a p p a r a tu s ; m a g n ific a tio n 3 0 0 x
RySv 4. O b ra z m ik r o s k o p o w y p o w ie r z c h n i P U R -II: a) f o l ia s u r o w a , b) p o m y c iu w o d ą z d e te r g e n te m, c) po e k stra k c ji h e k s a n e m w a p a r a c ie S o x h le ta ; p o w ię k s z e n ie 3 0 0 x
Treating of PUR I-IV by redistilled water at temp.
70°C through 24 h caused a small acidification of wa
ter, what probably was the result of partial hydrolysis of the ester bonds of fatty glycerides. The differences between pH of water and pH of the extracts from PUR MV, were measured in the range of 1.03 - 1.84 after such heating (Table 6) and were lower than it was fo
und for Pellethane 80 AE (pH displacement 2.14) [18].
Differences between mass of dry residues of such ob
tained water extracts from PUR I, II, III and dry resi
dues of equal water volume (0.25 mg) were respecti
vely 0.25, 1 and 0.50 mg e.g. were much lower than difference maximal allowed in USP XXII (15mg).
We investigated also the stability of PUR II and IV on extraction by water and hexane at reflux temperatures, according to Code of Federal Regu
l a t i o n ^ ] . The dry extractibles estimated after 7 hours were lower than maximal allowed for both boiling water and boiling hexane extraction, but dry extractibles from next 2 hours refluxing were gre
ater than allowed (Table 7).
Table 7. S o lid resid u es o f the w a te r a n d h ex a n e extra cts fr o m P U R s a t reflu xin g , m g /c m 2
Tabela 7. S u c h e p o z o s ta ło ś c i e k s tr a k tó w z P U R w e w r z ą c e j w o d z ie i w r z ą c y m h e k sa n ie , m g /c m 2
Boiling water Boiling hexane first 7h next 2h first 7h next 2h
PUR-II 0.17 0.06 1.4 0.66
PUR-IV 0.12 0.06 0.91 0.27
Max. allow. [12]* 0.2 0.01 1.75 0.04
* after converting the milligrans/inch2 into mg/cm2
The IR spectrum of the dry residue of PUR-IV extract in boiling water (Fig. 5) exhibits the absorption band of the ether C-O-C groups (1096 c m 1) and a broad absorption band 3700 Cm1- 3000cm 1, which may be described to OH or/and COOH groups and, possibly to N-H groups (3485 c m 1). The band at 1606 cm'1 indicate the presence of the NH2 groups connected with cyclohe
xyl ring in the extractibles obtained from PUR in such drastic conditions of hydrolysis.
TOM 4 lipiec-sierpień 2000 r. SŁ oA tatnenty nr 4
Fig. 5. IR s p e c tr u m o f th e e x tr a c tib le s fr o m P U R - I V in b o ilin g w a te r (in K B r)
Rys. 5. Widmo absorpcyjne w podczerw ieni suchej pozostałości ekstraktu z P U R -IV w e w rzącej w odzie (w KBr)
Fig. 6. IR s p e c tr u m o f th e e x tr a c tib le s fr o m P U R - I V in b o ilin g h e x a n e (on N a C l)
Rys. 6. Widmo absorpcyjne w podczerw ieni suchej pozostałości ekstraktu z P U R -IV we w rzącym heksanie (film na N aC l)
S to A tw c e n c f, nr 4 lipiec-sierpień 2000 r. TOM 4
The dry residue of PU R -IV extract’s in boiling hexane shows on IR spectrum (Fig.6) small absorp
tion bands at 3400-3500 c m 1, at 1720-1700 cm '1 (C=0) and at 1250 c m 1 for C-O-C bands from ester groups, what may suggest the extraction of some glycerides.
The sorption of natural (sunflower) oil in PUR foil was m uch greater than oil sorption m easured for Pellethane 2363-80A and poly(carbonateurethane)(Al- drich)(Table 8 ). It arises from a certain affinity of fat to the PURs containing incorporated structure of the natural fat acids glycerides and also from the lower density of obtained PURs, connected with the structu
re of castor oil and the structure of isomeric, cycloali- Table 8. Sorption o f sunflower oil in PURs
Tabela 8. Sorpcja oleju słonecznikowego w PUR Polymer Oil sorption, Am /m 0, %
PUR-I 2.6
PUR-III 6.8
PUR-IV 8.2
Pellethane 2363-80A 0.71
PU-PC* 1.15
a16-p u r** 14.8
* polycarbonate urcthanc)”soft” (Aldrich) from poly(l ,6-hcxyl-l ,2 cthyl- carbonatc)diol, MDI, 1,4-BD
**poly(urcthaneurca) with CI6 aliphatic side chains [10]
phatic diisocyanate (SM DI).
The data Table 8 indicate that oil sorption in de
scribed in this paper PURs was however lower than m easured for poly(urethaneurea) with long side ali
phatic (C |6) group, obtained earlier in our laborato
ry [10], In the polym ers obtained from PTM G 2040 the oil sorption was several times greater than in PUR-I from PTM G 1000.
Conclusions
PURs obtained in this work from cycloaliphatic diisocyanate and polyols with castor oil participation in regard to physical properties fulfil the requirements for polymeric m aterials used in medicine. The stabili
ty with treatm ent by hot water is for these PURs satis
fied. In com parison to typical polyurethanes the obta
ined PURs are characterized by lower water sorption but greater sorption of natural fat.
It is necessary to investigate in future researches how the m odification of PU R by the structure of ca
stor oil will im prove album ins binding and induce bet
ter hemo- and biocom patibility in com parison to typi
cal PUR. It is also purposeful to verify if such chem i
cal structure PU R would not enlarge a tendency to calcification on polym er surface in living tissues.
References
1. ‘’Polyurethanes in Biomedical Engineering”, Ed.
Planck H., Egbers G., Syrel., Elsevier Science Publ.
B.V.: Amsterdam 1984
2. Lelah M.D., Cooper S.L.: ‘’Polyurethanes in Medi
cine”, CRC Press, Boca Raton, 1986
3. Gogolewski S., Coll. Polym. Sci. 1989, 267(9). 757 4. SzycherM., Poirier V.L., Ind. Eng. Chem. Prod. Res.
Dev. 1983, 2Z 588
5. Pinchuk L., J. Biomat. Sci. Polymer Edn. 1994, 6 (3), 225
6. MasiulanisB., Całusiński G., Elastomery 1997, Vol.
I , 6 ,3
7. Koegh J.R., Eaton J.W., J. Lab. Clin. Med. 1994, 124(4), 537
8. Haycox C.L., RatnerB.D., J. BiomedMat. Res. 1993, 2Z 1181
9. Grasel T. G., Cooper S.L., J. Biomed. Mat. Res. 1989, 23, 311
10. Całusiński G., Masiulanis B., Jurkowski P, in press, J. Biomat. Appl. 2000, 15, 1
11. Hilditch T.P, Williams P.N.: ”The Chemical Con
stitution o f Natural Fats”,
Chapman & Hall, London, 1964,p. 264
12. Ulrich H ,.Bonk H.W. in ‘’Polyurethanes in Bio
medical Engineering”, Ed. Planck H., Egbers G., Syre J. Elsevier Science Publ. B.V, Amsterdam, 1984, p. 165
13. Walder A.J., Plastics Eng. 1998, April, 29
14. Technical Fact Sheet Division of CardioTech In
ternational, Woburn, USA, 1998
15. Zhu K.J., Lin Xiangzhou,Yang Shilin, J. Appl. Po- lym.Sci.1990, 39.1
16. Saxena P.K., Srinivasan S.R., HrouzJ., llavskyM., J. Appl. Polym. Sci. 1992, 44. 1343
17. Masiulanis B., Brzeska J., Smoczyński B., Book of Abstracts, Fifth International Conference on Fron
tiers o f Polymers and Advanced Materials and NATO Advanced Research Workshop on Polymers and Composites fo r Special Applications, 1999, Poznań, Poland, p. 226
18. Piątkiewicz W. in “Problemy biocybernetyki i in
żynierii biomedycznej”, Wydawnictwo Komunika
cji i Łączności, Warszawa 1990, 3, p. 63
