of methyl linolenate i.: favored in the mono- and diformyl products. Although the triformyl ester products of linolenate have not been well tharscterized, the iequerice monoformyloctadecadienoate (2) -+ diformyloctadeceIioate (5) + triformyloctadecanoate 16) is supported by our analyses of products. The major 1,4,i-tnformyl products expected from this sequence Ivould he methyl 9(10)-12(13)-15( 16)-triformyloctadecanoate (6). Acknowledgment
We are grateful to R. L. Reichert for pressure hydroformylation.: to c'. A . Glass for nmr analyses; to C. E. McGrew for elemental analy3es; to J. 11. Snyder for the methyl linoleate, linolenate, and cis-9,cis-15-octadecadienoate; to E. J. Dufek for a sample of methyl 9,12-dicarbomethosyoctadecanoate; and to E. H. Pryde for helpful discussions. literature Cited
Adkins, H., Williams, J. I. R., J . Org. Chem., 17, 980 (1952). Brown, C K., Wilkinson. G., J . Chem. Soc., it, 1970,p 2753. Brown, C K., Wilkinson, ( i . , Tetrahedron L e f t . (22), 1725 (1960). Butterfield, R. 0 , Uutton, If. J , Scholfield, C. R., -4nal. Chem., 38, 86 (1966). Butterfield, 13. O., Sdiolfield, C. It., Dutton, H. J., J . Amer. 021 Chem. Soc., 41, 603 (1964).
l h f e k , E. J., Cowan, J. C., Friedrich, J. P., h d . , 47, 31 (1970). Evans, I)., Osborn, J. .\., Wilkinwn, G., J . ('/mi. S O C . , A , 1968, p 3133. Fell. €3.. Iiuoiliu
5
.3
z I?
.2
u
I
2
.I
D 20
40 60 80 IO0 D U R A T I O N OF IMMERSION TESTS (MINUTES)
120
Figure 1 . Determination of sodium ion permeation rates a t various temperatures across coating systems of PVHPElvacite by use of coated soda-glass rods of 3-mm diam at 1 .O-in. immersion. Test solutions were continuously agitated; dilute phosphoric acid a t pH = 2.57
The water absorption characteristics of the coating were measured by weighing the coated glass rods before and after exposure a t an immersion depth of 1 in. in water a t controlled temperatures for various lengths of time. The observed differences in weight permitted calculation of the percent watw absorption. Other water absorption determinations were performed by gradual evaporation from water-saturated coatings in a thermogravimrtric analyzer. T o determine the effectiveness of each coating in preventing the dissoliition of glass, coated glass rods were first suspended in vertical position inside Erlenmeyer flasks, and a standard length of the coating was immersed in a 200-ml volume of an aqueous test solution. Diff ererit sets of exposure tests were performed in acidic solution (in phosphoric acid at p H = 2.57), in distilled water, and in basic solution (in barium hydroxide a t pH = 10.7). The solutions were maintained a t constant temperature and under continuous agitation by use of a hot plate with a magnetic stirrer. Testing temperatures ranged from 45' to 7 5 ° C . +Itstandard intervals, i.e., after 20, 40, 60, 90, and 120 min of elapsed exposure time, 10-ml samples were transferred by pipet into polyethylene sample bottles. These solution samples were subsequently analyzed for their sodium ion concentration on a Perkin-Elmer (Model 403) atomic absorption spectrophotometer. The sodium concentrations in these solutions are a measure of the quantity of soluble glass that permeated through the coating system. The sodium concentrations (in ppni) were plotted as a function of immersion time t o determine the average permeation rate. The coating thickness, glass surface area, and immersed surface area were held constant. Results
20
40
60
80
I00
120
D U R A T I O N OF IMMERSION TESTS ( M I N U T E S )
Figure 2. Determination of sodium ion permeation rates at various temperatures across coating systems of PVHPElvacite b y use of coated soda-glass rods of 3-mm diam a t 1 .O-in. immersion. Test solutions were continuously agitated; dilute barium hydroxide a t pH = 10.7
Tlie requirements on such a coating are quite stringent, for it i; merely a first prerequisite that the coating must resist teiid(,iicies to snell or to undergo hydrolytic decomposition in long-term contact with moisture. Also, bonding onto the hitbit,ratc must hc strong enougli to withstand any tendencies for t,lie coating to loosen up! owing to the gradual arrival of moisture a t the glass-polymrr interface. To establish strong iiitcractioiij with the soluble glass, a hydrogen-bonding polyacid was used as a priming layer, onto which a polymeric barrier coating can he attached firmly. Experimental
11ost experimental work was performed with glass rods of approxirnately 3-mm diameter, which were prepared by drawing from a melt of soda glass containing 65% silica. The rods \$-ere cut to lengths of roughly 6 cm, and both ends were fire ~)olishcci.The glass rods iwre t,lieii dip-coated for a lcngtli of about 5 c ~ nT. o jmtcct t,he upper edge of the coating during inimersion tests iii aqiic'ous .solutions, the uncoated portion of the rod was coi-crctl witli tightly fittiiig rubher tubing. 54
Ind. Eng. Chem. Prod. Res. Develop., Vol. 12, No. 1 , 1973
The most severe requirement for the glass coating is resisting deterioration and maintaining good adhesion under attack by hot water. Many known adhesives will bond effectively to glass (Moser, 1954), but most cannot withst,and this test. Our most successful coating system consisted of two polymer layers : an undercoating polymer chosen for its water resistance and excellent adhesion onto glass; and an outer coating polymer chosen for its excellent hardness, gloss, excellent adhesion onto the undercoating polymer, and water imperviousness. Thc undercoating polymer, poly.c.inyl hydrogen phthalate (PVHP) , provides polar carboxyl groups for dipole-dipole interactions with the glass, and the bulky hydrocarbon chain structure virtually prevents dissolution iri n.ater. Many substances that bond to polar surfaces are also susceptible to attack by thc polar molecules of water. For example, polyvinyl alcohol bonds to glass extremely well, but t,he polymer is dissolved or s~vollcnby water, deperiding npon the polymer molecular weight. I'olyviriyl hydrogen phthalate shows much weaker interact,ions with water, and a suitable solvent is methylethylketone. In esperimpntal work, the glass surface was dip-coated with a solution (80 g PVHP/l. RIEK) of the subcoating material, which readily dries to yield a hard, trail;parent film of about, 1-mil t,hickiiess on our sample rods. Tlie undercoating provides a good surface for seating the barrier coating, 1,ecausc both polymer compositioiis were chosen to possess ester structures of related types. A suitable oiit,er barrier coating was D u Poiit Elvacite 601 -1, which was furnished as a lacquer. Tlie polymcr, supplied in toluene solution, was a metliylmet,hacrylate copolymer with about 50% ~)utylmetliacrylat,egroupiiqp Infrared analysis reveals that some carbosyl groups are also present for im-
proved adhesion onto polar surfaces. A vinylidene chlorideacrylonitrile copolymer (Saran-310, Dow Chemical Co.) is also suitable as a top coating, but in our application i t was more sensitive to water when tested at elevated temperatures. The Elvacite 6014 top coating is relatively nonabsorbent. Our determinations detected approximately 0.7% water absorption during exposure for 7 2 h r a t 25"C, for a n experimental coating of 2-mil thickness. An accumulation of 0.30.4y0 in 24 h r for methylmethacrylate homopolymer was cited by Billmeyer (1982). I n hot water the experimentally attained coating system remains transparent, maintains excellent adhesion, shows no obvious signs of deterioration, and allows permeation of sodium to only a very limited extent. With some inferior coating formulations, separation of the coating from the glass is observed, and these effects are explained b y a n osmotic pressure effect. When the water molecules premeate the coating and reach the glass surface, dissolution of some glass occurs, creating a concentrated solution under the coating. I n attempts to reach equilibrium, more water molecules will migrate through the coating membrane to dilute the concentrated solution underneath, aiming to establish equal concentrations on both sides of the coat'ing. This influx of water mmolecules generates a pressure between the solid surface and the coat'iiig; thus, we explain the observed tendency of some coatings to balloon away from the glass surface. Hoiveve r, with coatings t h a t provide better adhesion onto soluble glass, these pressure effects can be suppressed effectively. Although water is soluble within the coating to a limited extent only, some detectable amounts of sodium can permeate into the aqueous test: solution during routine immersion procedures with coated glass rods. After exposure up to 2 hr, the detected sodium concentrat,ions ivithin the test solut'ions never exceeded 1 ppm; and all att,aiiied concentrations in excess of 0.5 ppm were attributable to runs a t the highest test temperatures (65' or 7 O O C ) . For purposes of comparison, uncoated sodium silicate rods will accumulate 1 ppm of sodium in about 11 min a t 25'C under st'aiidard test procedures. All these data compare to a typical sodium concentration of 8 ppm in t a p water available in this laboratory and a sodium concentration of 24 pprn in a sample of Yew York City water. Typical plots of sodium ion coiiceiitrat,ion vs. immersion time in aqueous solution are given in Figures 1 and 2 . At each solution temperature, the slopes of these plots were used to characterize the average permeation rat,e. OIving to the changing volume of water caused by the removal of small (10 ml) samples, the graphs should exhibit a n increasing slope, but this effect was virtually undetectable despite our experimental precautions to keep the depth of sample immersion constant. From the rate data, typical drrhenius plots were constructed for each series of experiments (Figure 3). Each graph exhibits a change in dope at 60°C, which is interpreted t o be the glass transition teinperature for the barrier coating. This temperature is known rather precisely, and any uncertainty is limited to + l 0 C . Literature data cited 17" and 88OC as as the respective brittle-point temperatures for butyl- and methylmethacrylate homopolymers (Riddle, 1954) ; the glass transition temperature of the copolymer under consideration was expected to lie roughly in the middle of this t'emperature difference. At the transit'ion temperature under discussion, the copolymer coating undergoes change from the glassy state to the rubbery state, and a concomitant change in the temperature dependence of sodium permeation rate is observed. I n
-2.0-
0 DISTILLED
WATER
0 DISTILLED WATER
=
I
W c
z
+--. --
W 4
0
2
-2.5-
0 ACIDIFIED SOLUTION A ACIDIFIED SOLUTION
-
U
0
'C>
0 B A S I C SOLUTION
n
1
-
-3.0-
0 -1
-3.5
-
.00290
.00300
.003100
TEMPERATURE-'
Figure 3.
Arrhenius plots showing temperature dependence
of sodium ion permeation rates across coating systems of PVHP-Elvacite. Solutions of different pH were used
the rubbery state the sodium permeation rate is less strongly affected by changes in temperature, owing to t'he smaller activation energy required for molecular permeation. Any significant, change in solubility of water within the rubbery coating could also account for t,hisbehavior, since permeability depends both upon the diffusion coefficient and upon solubility within the material mat,rix (Ribble, 1954). The coating in the glassy state appeared to be unaffected b y the mild p H differences between the test solutions, and all three series of experiment,s yielded the same temperature dependence for the rate of sodium permeation. These findings can be interpreted to mean that the same activation energy applies in all cases for the glassy state. I n the rubbery state the coating systems remained unaffected by acid or distilled water, but in basic solution the rubbery coating evidently weakened a t higher temperatures. This effect allowed a greater rate of increase in permeation rate with temperature than encountered in other series of experinieiits. The base-initiated phenomena were history dependent, sirice reexamination with the same coated rod a t a lower temperature (62'C) later exhibited a faster rate than a t 70°C. The coating had undergone permanent daniage upon espoaure to the hot, basic test solution. Such degradation pheiiomena may be caused by the formation of cracks and fissures or to some uniform decrease in the coating thickness during contact by bhe basic solution a t high temperat,ures. Seymour and Steiner (1955) point out t h a t acrylic polymers have the tendency to undergo saponification in basic solutioiis, but methylmethacrylate homopolymer is quite resistallt to this reaction. Discussion
I n most of the practical considerations of coating permeability, the glassy state of t'he polymer is important, since this state usually prevails a t the use temperatures for coated containers; i.e., at room temperature and below. By use of the lon--temperature portion of the Alrrheiiiusplot, an extrapolation can readily be performed to estimate the sodium permeation rate a t 25°C. S o further di5continuities in thc plot are expected below the glass transition temperature. From the extrapolation, one calculates an accumulation rate of 1.7 ppm sodium per year in the volumes of test solutions routinely employed, assuming continuous agitation a t all times. This estimate corresponds to a calculat'ecl rate of Ind. Eng. Chem. Prod. Res. Develop., Vol. 12, No. 1 ,
1973 55
sodium silicate permeation of 5.5 X 10+ gram per year per cm* of coating surface. Without agitation the dissolution rate is expected to be considerably smaller. According to this calculation, any 2-hr test a t 50°C corresponds to exposure a t room temperature for approumately 15 days. Similarly, 2 hr at 60°C corresponded to approximately 105 days a t room temperatures. Above 60°C the coating is in the rubbery state, and the data cannot be correlated directly nith room temperature data. The accumulation rate of 1.7 ppm per year can be contrasted nith the computed attainment of approximately 48,600 ppm of sodium ions per year for an uncoated sodium silicate glass rod a t 25”C, assuming continuous agitation. In all thew calcnlations, it is assumed that the surface area of the rod samples remains constant, although the diameter of uncoated rod< nil1 actually become slightly fmaller as dissolution progresses, and therefore, so \t 111 the surface area. Evaluation of the slope of the -4rrhenius plot pwmits a calculation of the activation energy E,, since E , = - (slope) X 2.3 R. For the glaqiy state the activation energy n a s calculated to be approximately 35 kcal/mol, but for the rubbery state the activation energy n as calculated to be significantly lower, namely. ahout 4 kcal/mol. Because of deterioration of coatings 111 alkaline media, the latter type of calculations
could only be performed with data from the experimental series that used distilled water or acidic test solutions. Aside from the visualized application on surfaces of container structures, the reported coating system can conceivably find uses in contact with glass compositions other than soda glass. I n experimental tests various glass specimens were successfully adhered to by the PVHP undercoating, and a hard, water-resistant water barrier was then provided by the topcoat formulation described. literature Cited
Billmeyer, Jr., F. W., “Textbook of Polymer Science,” p 502, Interscience, New York, N.Y., 1962. M;ser, F., “Selecting Glass Adhesives by Strength Tests,” in Adhesion and rldhesives-Fundamentals and Practice,” Wiley, New York, N.Y., 1954. Riddle, E. H., “1Ionomeric Acrylic Esters,” pp 67-132, Reinhold, New York, K.Y., 1954. Seymour, R. B., Steiner, R. H., “Plastics for Corrosion-Resistant Applications,” p 52, Reinhold, Xew York, N.Y., 1955. RECEIVED for review February 7 , 1972 A 4 ~December ~ ~ 15, ~1972~ Presented at the Division of Organic Coatings and Plastic Chemistry, 162nd Jleetini, .4CS, Washington, D.C., September 1971. Work siipported by Grant EC-00033 from the Environmental Protection Agency.
Macroreticular Polymeric Adsorbents David C. Kennedy Research Division, Rohm and Haas Co., 5000 Richmond Street, Philadelphia, Pa. 19157
A series of new macroreticular resinous adsorbents has been developed. These materials are hard, insoluble beads of porous polymer characterized b y a spectrum of surface polarities and b y a variety of surface areas, porosities, and pore-size distributions, Owing to these differences in surface properties, the polymeric adsorbents display a wide range of sorption behavior and can be employed in both aqueous and nonaqueous systems. A sizable amount of adsorption data suggests that these materials will have practical applications in diverse fields. A major field i s in waste treatment where the polymeric adsorbents show promise for decolorizing kraft pulp mill effluents and for removing phenols and chlorinated pesticides from industrial wastes. Other interesting applications exist in chemical processing, particularly for product stream purification, and in the pharmaceutical field for adsorbing vitamins and enzymes.
R e c e n t studies have led to the cievelopment of a new series of synthetic polymeric adsorbents (identified as .Imberlite XAI) macroreticular adsorbents. hmberlite is a registered trademark of the Rohm and Haas Co., Philadelphia, Pa.). r . 1hese materials have a varietl- of surface polarities aiid caii be prepared wit,h varying surface areas aiid average poresize distributions. They have demonstrated applicabilit’y iii waste treatment areas-particularly for the treatment of kraft pulp niill effluents. The synthesis of polymeric adsorbents was derived from a study of the preparation of porous macroreticular ioii-excliaiige re,siiis (Kuiiiii et al.. 1962). The first step in the preparation of ioii-exchange resiiis is the formation of a styreiietliviiiylbenzene copolymer polymei,ized in an aqueous suzl c >ellsion. The average particle size of these spherical beads is 56 Ind. Eng. Chem. Prod. Res. Deve!op., Vol. 1 2 , No. 1, 1973
approximately 0.5 mm. This size is chosen as a compromise because ion-exchange processes are diffusion controlled, and it is desirable from a kinetic point of view to have as small a particle (giving as short a diffusion path) as possible. However, the hydraulic expansion and pressure drop would be excessively high if particles significantly smaller than 0.5 m m were used in large columii installations. Macroreticular resins are highly porous structures in which each 0.5-nim bead consists of many small microspheres whose dianiet,er is as small as 10-4 inm (Kim and I
