Determination of the solubility parameter of cellulose acrylate using inverse gas chromatography

Chinese Science BulletinSCIENCE IN CHINA PRESSDetermination of the solubility parameter of celluloseacrylate using inverse gas chromatographyZHAo Shu, ZHANG Fei. ZHANG WenWen SHi BaoLiHeilongjiang Key Laboratory of Molecule Design and Preparation of Flame Retardant Materials, Northeast Forestry University,Harbin 150040, chinaThe solubility parameters of cellulose acrylate substituted degree 2.12(CEA)have been calculated fromthe measured retention data by inverse gas chromatography at various temperatures. The weight fraction activity coefficients of the solvents at infinite dilution(m, the Flory-Huggins thermodynamic in-teraction parameters between CEA and solvents (xi), the excess molar heats of mixing( AHi), the par.tlal molar heats of mixing at Infinite dilution(AHi), the solubility parameters of solvent(E), and thesolubility parameters of CEA (E), were calculated at various temperatures. The &f of the CEA was 17.32,1800,1813,18.54,19.39at55,60,65,70and75℃, respectively.solubility parameter, cellulose acrylate, inverse gas chromatographyCellulose is one of the richest and reproducible natural mer and the solvent Inverse gas chromatography (IGC)polymers in the world and is applied vastly to spin, pa- has been proved to be a rapid and consistent method toper making, pharmacy, packing, as well as flexible liq- study polymer-solvent interactions 5). It is well estab-uid crystal display and separate membrane materials. 2. lished that weight fraction activity coefficients and heatsIf unsaturated groups were bonded to cellulose, and then of dilution may be derived accurately for these systemscopolymerization with ethenyl monomer, one could de- from IGC measurementssign and synthesize the macromolecule chain-orderedThe main focus of this work was to determine themembranes controlled well in three-dimension web solubility parameter of cellulose acrylate (82), that wasdisplay. Whereas, one of the key technologies of form- tion volumes of the probe molecules, furthermore toing membranes controlled well in structure is the selec- calculate the weight fraction activity coefficients of thetion of the solvents and regeneration bath of cellulose or solvents at infinite dilution(32/, the Flory-Hugginsits derivativesthermodynamic interaction parameters (x 12), and theThe solubility parameter is an important thermody- solubility parameter of the solvents(), from which thenamic parameter to characterize the polymer solution solubility parameters of cellulose acrylate(&2),wereproperty.It has an important theoretical meaning in de- gained. This work not only afforded a theoretical guidtermining polymer dissolution behavior and characterance for selecting solvents of CEA, but also proved theGenerally, the solubility parameter is measured by staticstate, for example the Swelling Method the Viscosimet-Received Jannary 28, 2007: sccepted May 10, 2007ric Method, and the Turbidimetry Method. These meth- doi: 10.1007/114ods not only consume time but also obtain only the Comm中国煤化工Suppor-nology Sustentation of Chinathermodynamic parameters of the mixture of the poly- (GramINCNMHGwww.scichina.comwww.springerlink.comhinese Science Bulletin I November 2007 I vol. 52 I no. 22 13051-3055IGC technology being effective and rapid for determina v0ing the solubility parameter of polymers, that has a uni-△H=-Rversal applied value.△H1=RaIn 21 Principle of determining solubility pa-rameter of polymer by inverse gas chro-matographywhere R is the gas constant, Bl is the second virial coef-IGC is an analytical technique used widely to study sur- ficient of the solute, Pi is the vapor pressure of the sol-face properties of adsorbents, cellulose, starch or other vent at temperature T(K), Mi is the molecular weight ofpolymers. Probe solvents with known properties arethe solvent, and V, is the molar volume of the solvent.jected into the column packed with polymer, and theThe vapor pressures Pi were taken from ref. [12]retention time of these probes are measured at infinite The values of Bul and Vi were calculated at the columndilution. The interactions between the probe solvents temperature, and Bu has been calculated using eqand the polymer materials and other thermodynamparameters are calculated from the retention times, andthe solubility parameters of solvents and polymer areThe retention data determined with inverse gas chromatography experiments were used to calculate the0.0375(7-1thermodynamic functions of the solute dissolution in where v and t are the critical molar volume and thecellulose acrylate as well as Hildebrand's solubility pa- critical temperature of solvent, respectively, and theserameter. The probe specific retention volume, v& cor- values are shown in table l and n is the number of carrected to 273. 15 K was calculated from the standard bons in solvent molecule. The molar volumes of solventchromatographic relation6, 7.V, were calculated by eg (8):V0=273.15×J×F(1)where At= t-fm is the difference between the retentiontime of solvent and marker f is the flow rate of carrierwhere P is the solvent density at room temperature, anrted in ref. [12gas measured at room temperature, m is the mass of thepolymer of stationary phase, and J is a correction factor Table 1 Physical constants of solvents: critical density Pe, critical vol-for gas compressibility defined by the following rela- ume Ve critical temperature Te, and critical pressure P.Te(k) Pc (MPa)n-hepane 0.232431.897540.152.70J 3(P/PFl-ocrane492.371(P/P)-1M-nonane0236543475594.560.228624000617.70where Pi and Po are the inlet and outlet pressures, respectively.IGC can be used to measure the Flory-Huggins interGenerally, vg decreases with an increase of tempera- action parameters at infinite dilution by the followingture in all investigated systems as expected for an exo- equation [7, 13),thermic sorption process. The weight fraction activitycoefficient,5 the molar heat of solution, AH119,the石如21521r-1average partial molar enthalpy at infinite dilution of thesolvents, AHi, and the molar heat of vaporization, AHv,The solubility parameters of probes S can be calcu-were calculated according to the following equa- lated according to eq. (10) and d2 according to the fol-lowing eq. (1127315RF中国煤化工2PygM, RT B1-1),CNMHGCED)2,(10)ZHAO Shu et al. Chinese Science Bulletin I Nowember 2007 I vol. 52 I no 22 13051-3055where AHy is the energy of evaporation and Ced the column was conditioned at 105 C and fast carrier gascohesive energy densiflow rate(20 mL. min )for 12 h prior to measuring需(篇(ll) The flowas thenme that was 14.73 mL. miIf the left hand side of eg (11) is plotted against 6, a ured from the end ofcolumn with asoap bubble flowstraight line having a slope of 2b/(Rn) is obtained. Themeter. The injector and detector temperatures weresolubility parameter of the stationary phase, 5, was heated to 130C. The injcalculated from the slope of the straight line0. 1 uL using Hamilton syringes. At least five separatevapor injections were made for each probe. The IGC2 Experimentalexperiments were performed at 55, 60, 65, 70 and 75C.2. 1 MaterialsThe column oven was in a continuous operation fromthe beginning of the work to the end.The polymer is cellulose acrylate(Figure 1) synthesizedin the said laboratory as polymeric stationary phase in 3 Results and discussionIGC. The synthesis method, was that the cellulose,cotton linters of lower DP 505-545 was dissolved in 3.1 Solubility parameters of probe solvents5%-10% lithium chloride/N, N-dimethylacetamide For each of the alkane probes over the entire range of(MAc)mixture solution forming homogeneous phase temperature, the retention time at infinite dilution wassolution, then acryloyl chloride as acylating agent was recorded. The specific retention volumes of probes wereadded that reacted with cellulose so the cellulose acry- calculated by eq (). Figure 2 shows the plot of Nvglate was obtained, and the substituted degree of it was versus the inverse of the column temperature for a series2.12 determined by using an Euro Ea 3000 Elemental of n-alkanes As expected from eq (4), the function wasAnalyzer.linear. The speclic volumnes decrease linearly with anFor the IGC analysis, the n-alkane probes were n- increase of temperature. The molar heat of solution, AHipentane(Cs), n-heptane(C,), n-octane(C ) n-nonane was determined by the calculation of the slope(Cg)and n-decane(Cno). They were analytical gradesolvents and purchased from Tianjin Kermel ChemicalReagents development Centre, ChinaORHH-CHCH, or HFlgure 1 Chemical structure of cellulose acrylate286288290292292%2983003023043062.2 IGC instrument and experimental conditionT(K")Figure 2 Plot of Invi vs I/T for n-alkanes.The instrument was GC-900A gas chromatography(Shanghai TianPu Analytical Instrument Ltd, China), The weight fraction activity coefficient(321) was cal-equipped with a flame ionization detector(FID). Nitro- culated by eq. (3),and Figure 3 displays the plot ofgen was used as a carrier gas and n-pentane as an inner In 2i versus l/T for a series of n-alkanes, and the funcmarker, to determine the dead volume of the column. tion was linear as expected from eg.(3). The averageStainless-steel column (650 mm length, 2.56 mm i.d. partial molar enthalpy, AHi, at infinite dilution of thewas used and washed with acetone prior to use. The solventCEa was crushed and sifted with a 60-80 mesh to ol中国煤化工 (Figure3was calculatedtain the particles, and was packed into column. The by eqCNMHGand AHy are shownZHAO Shu et al. Chinese Science Bulletin I November 2007 I vol. 52 I no 22 1 3051-3055crease of temperature. Because the partial hydroxyl ofcellulose was substituted by the acryloyl, that destructedintermolecular hydrogen bonds in cellulose, so the CEAaim of this experiment was to get the solubility parame-ter of CEA, so that we can find out some solvents ormixed solutions which are similar to the value of CEA inorder to dissolve the CEA into homogeneous phase solrtion. Consequently, the dissolution behavior of CEA andthe properties of solution can be studied86288290292294296293003023.043.0644×10103/r(K33815KFlgure 3 Plot of Ins vs. I/T for n-alkanes343.15K48.L3.8×101in Table 2. Then the solvents solubility parameter 81was calculate by eq (10), and it is reported in Table 33.6×10Table 2 The thermodynamic parameters of cellulose acrylate with dif-32x10AHi(.mol") AH(Jmol AHy(kJmol)3.0x103549236873917928×Itn-octane13914014I14214314414.514614.7148149150n-nonane -30.409o,/(MPa)n-decane865545.064Figure 4 Plot of (8f/(RT-xiVi) vs. 81form-alkanesTable 3 The solvent solubility parameters at column temperature &Table 4 The solubility parameters of CEA at difference temperaturesTemperature(K)328.15333.15338.15343.15348.15328343.15348.15(MPay2)1732180018.13185419.39pane14.9631490114.8201477614712cane1452514490144341434914.323M-nonane14.19514.14314.0911403913.9864 Conclusionsn-decane 144904.4314.39514.34714.299 This work shows how IGC can be used to study theTable 3 shows that the solubility parameters of thpolymer as well as polymer solubility parameters. Thissolvents decrease with an increase of temperaturemethod appears to be a simple and good method to ob-3.2 Solubility parameters of cellulose acrylatetain polymer solubility parameter. The inverse gasBecause of polymers having no defined molar heat ofchromatography technique was successfully applied tovaporization, indirect ways have to be considereddetermining the thermodynamic data at infinite dilutionder to obtain solubility parameter of polymer. The rela- concernng polymer-solvent interactions: the weighttion between the solubility parameters of polymer and fraction activity coefficient of solvent, 32, the molarsolvent accords with eq. (1D), and Figure 4 shows the heat of solution, AHi, the partial molar enthalpy at infiplot of (SV/(RT-xi /Vi)versus &, of the probes at dif- nite dilution of the solvents, AHi, the molar heat of va-ferent temperatures, the solubility parameter of the CEA, porization, AHv, the Flory-Huggins interaction parame82, was calculated by the slop of the straight line, 28/ ter, x i2, and the solubility parameters, 81, were obtained(RT), and the values of &2 are reported in Table 4, that The solubility parameters of CEA, &, were 17.32,are smaller than the value of cellulose. The solubility 18.0中国煤化工60,6,70and75℃,parameter of cellulose acrylate increases with the in- respCNMHG3054ZHAO Shu et al Chinese Science Bulletin I November 2007 I vol. 521 no. 22 I3051-3055I Kuo Y-N, Hong J. A new method for cellulose membrane fal9 Comte S, Calvet, Dodds I A, et al. 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Cellulose methacrylate173-181synthesis and liquid crystalline bchaviour of solutions and gels.8 Shi B L, Feng C S, Wu Y L. A new method of measuring alcoholclusters in polyimide membrane: combination of inverse gas chro- 16 Ass B AP, Belgacem M N, Frollini E Mercerized linters cellulosematography with equilibrium swelling. J Membr Sci, 2004, 245( 1-2)characterization and acetylation in N, N-dimethylacetamide/lithiumhloride. Carbohyd polym, 2006, 63(1): 19-2sscience in china series B: chemistry lEDITORXU Guangxian(Hsu, Kwang-HsienCollege of Chemistry and Molecular EngineeringBeijing 100871, ChinaAIMS AND SCOPEScience in China Series B. 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Te: +49-6221-345-0FAx:+49-6221-345-4229;Emait:Sdc-JourNals@springer-sbm.com中国煤化工CNMHGZHAO Shu ot al. Chinese Science Bulletin I November 2007 I vol. 52 no 22 13051-3055