New hyperbranched poly(ether amide)s via nucleophilic ringopening of 2-oxazoline-containing monomers

To the memory of Prof. Dr. Sc.H.-J. Jacobasch(p)

Thomas Huber1, Frank Bohme1, Hartmut Komber1, Juraj Kronek2, Josef Luston2, Dieter Voigt1,Brigitte Voit*1

1 Institut fur Polymerforschung Dresden e.V., Hohe Straße 6, D-01069 Dresden, Germany2 Polymer Institute, Slovak Academy of Sciences, 84236 Bratislava, Slovakia

(Received: July 17, 1998; revised: September 10, 1998)

SUMMARY: An AB2 monomer containing one oxazoline and two phenolic units was synthesized. The poly-merization of the monomer 2-(3,5-dihydroxyphenyl)-1,3-oxazoline inN-methylcaprolactam resulted in awell-defined and fully soluble, high molar mass, hyperbranched polymer with etheramide structure. Thehydrolysis of some oxazoline groups as side reaction limits the achieved molar mass when the polymerizationis carried out in tetramethylene sulfone or in bulk. The polymers were characterized by one (1D) and two(2D) dimensional1H and13C NMR spectroscopy which allowed to determine the degree of branching to be50% as expected from statistics. DSC and TGA measurements revealed a glass transition temperature of1768C and a decomposition onset of 3308C. The thermal ring-opening reaction was studiedin situ by DSCmeasurements.

IntroductionThe interest in hyperbranched polymers1) increasedrapidly over the last years due to their similarities to per-fectly branched dendrimers. Their high degree of branch-ing reduces the viscosity in melt and solution, improvesthe solubility and introduces many functional groups intoa polymer. These are polymer properties which are espe-cially of interest for applications where an absolute con-trol of the molar mass and the perfect structure of dendri-mers are not required, e.g., in coatings and in blends.Most of the hyperbranched polymers have been synthe-sized by different polycondensation reactions coveringpolyesters, polyamides, poly(ester amide)s, polyure-thanes, poly(ether ketone)s, poly(ether sulfone)s, poly(sil-oxysilane)s and many other structures2–6). In addition,recently, the so-called self-condensing vinyl polymeriza-tion, which involves a cationic or radical polymerizationprocess7–11), has been used for the synthesis of hyper-branched polymers. Thus, already a broad variety ofhyperbranched structures exists. Hyperbranched poly-amides12–14) and especially poly(ether amide)s, however,are hardly known, although soluble and highly functionalpolyamides are of special interest. A first approach to thesynthesis of hyperbranched aromatic-aliphatic poly(etheramide)s was described previously by Voit and co-work-ers15). Jikei et al.16) described the synthesis of fully aro-matic poly(ether amide)s. Both approaches use conven-tional polycondensation reactions of acids and amines toform the hyperbranched structure.

In this work we present a new way for the synthesis ofhyperbranched aromatic-aliphatic poly(ether amide)s

with phenolic end groups via the nucleophilic ring open-ing reaction of 2-oxazoline-containing monomers. It iswell known that the reaction of 2-oxazolines with car-boxylic acids, thiols and phenols leads to esterami-des17–19), thioetheramides20, 21) and etheramides22, 23). Thesynthesis of linear poly(ether amide)s in melt and sol-ution of monomers containing one 2-oxazoline and onephenolic group was described by Mu¨lhaupt et al.24). In thefield of hyperbranched materials, oxazolines were used tomodify the focal unit of hyperbranched polycarbosilanesin order to obtain a hyperbranched macromonomer25) andfor the preparation of star polymers with a hyperbranchedcore and poly(2-methyl-2-oxazoline) arms26). The poly-merization of an AB2 monomer with two phenolic groupsand one oxazoline function leads now to a new hyper-branched structure.

Experimental part

Materials

3,5-Dihydroxybenzoic acid (1) and 2-ethanolamine werepurchased from Fluka and used without further purification.Methyl-3,5-dihydroxybenzoate (2) was prepared from1using a standard esterification method27). Tetramethylene sul-fone was dried over 4 A˚ molecular sieves, andN-methylca-prolactam was dried over CaH2. Both solvents were distilledright before polymerization. All flasks were evacuated andpurged with nitrogen three times. The reactions were carriedout in an inert atmosphere using dry solvents.

Macromol. Chem. Phys.200, No. 1 i WILEY-VCH Verlag GmbH, D-69451 Weinheim 1999 1022-1352/99/0101–0126$17.50+.50/0

126 Macromol. Chem. Phys.200,126–133 (1999)

Newhyperbranchedpoly(etheramide)svia nucleophilicring openingof 2-oxazoline-containing monomers 127

Instruments

The inherentviscositieswere measuredwith an automatedUbbelohdeviscometerin DMF thermostatedat 308C. DSCmeasurementswereconductedwith a PerkinElmerDSC7inaluminiumpansundernitrogenat a heatingrateof 10 K/minand TGA measurementswere conducted with a PerkinElmer TGA7, again at a heating rate of 10K/min.500.13MHz 1H NMR spectraand 125.74MHz 13C NMRspectrawererecordedwith aBrukerDRX 500NMR spectro-meterin 5 mm o.d. sampletubes.1H-1H correlatedspectro-scopy (COSY), 1H-13C heteronuclear multiple quantumcoherence(HMQC) and 1H-13C heteronuclearmultiple bondcorrelation (HMBC) experimentswere recordedusing thestandardpulse sequencesincluded in the Bruker softwarepackage.All spectraweremeasuredin DMSO-d6 with tetra-methylsilaneas internal standard.IR spectrawere recordedwith BIO-RadFTS155spectrometerusingKBr pellets.TheMALDI-T OF massspectrawere recordedby HP G2025AMALDI-T OF system.All spectraweremeasuredin a THF/2,5-dihydroxybenzoicacid matrix with K+-modifier using alaserenergy of 5.79 lJ. GPCanalysiswasperformedusingsolutionsin distilled N,N-dimethylacetamidewith 3 g/L LiCland2 vol.-% H2O (column:ZORBAX PSM60 or ZORBAXPSM Trimodal, calibratedwith polystyrenestandards,flowrate: 0.5 mL/min). Melting points were measuredby lightmicroscopywith a heatingtableat a heatingrateof 1 K/min.TLC measurementwasmadeusing0.25mm silica gel withfluorescentindicatorin methanol.

Synthesis

The monomer 2-(3,5-dihydroxyphenyl)-1,3-oxazoline(4)waspreparedsimilarly asdescribedby Black et al.28) for thesynthesisof oxazolinesin general.

N-(2-Hydroxyethyl)-3,5-dihydroxybenzamide(3): 2-Etha-nolamine(32.9g, 539mmol) wasaddedat roomtemperatureto 269.5mmol (45.68g) of 2. Thesolutionwasheatedup to1308C for 4 h, during that time the methanolformedby thereactionwas distilled off continuously. After reactionwascompleted,the excessof 2-ethanolaminewas removedinvacuum and the product was recrystallizedfrom ethanol.Yield: 62%.

1H NMR (DMSO-d6): d = 9.38(s, OH); 8.10(t, NH); 6.66(s,H3); 6.34(s,H1); 4.65(t, OH); 3.47(q, H7); 3.27(q, H6).

13C NMR (DMSO-d6): d = 166.64 (C5); 158.27 (C2);136.91(C4); 105.50(C3); 105.04(C1); 59.85(C7); 42.16(C6).

2-(3,5-Dihydroxyphenyl)-1,3-oxazoline (4): 46 mmol(9.07g) of 3 were suspendedin 36 mL methylenechlorideand cooled to 08C. Within 2 h thionyl chloride (8.4mL,115.6mmol) wasaddeddropwiseunderstirring. After addi-

tional 2 h, the ice bath was removedand the solution wasstirredat roomtemperatureuntil gasdevelopmentwascom-pleted.The precipitatewasfiltered off andthendissolvedinice-water. Sodium hydrogencarbonatewas carefully addeduntil the solution was neutral.During the addition the pro-duct precipitated,was isolated by filtration, and dried at508C in vacuum.One single signal at Rf = 0.77 could beobservedby TLC measurement,which could be assignedtothe product. Yield: 63%; m.p.: 1908C (light microscopy);2088C (DSC).

1H NMR (DMSO-d6): d = 9.54(s, OH); 6.77 (s, H3); 6.36(s,H1); 4.34(t, H7, 3J = 9.5Hz); 3.90(t, H6).

13C NMR (DMSO-d6): d = 163.01 (C5); 158.25 (C2);128.99(C4); 105.74(C3); 105.25(C1); 67.03(C7); 54.22(C6).

C9H9O3N (179.16) Calc. C 60.33 H 5.06 N 7.82Found C 60.25 H 5.08 N 7.69

Thermalpolymerizationof 4 in bulk

4 (3.3g, 18 mmol) was placed into a Schlenk flask. Theflask was placed in an oil bath preheatedto 2208C. Themonomermelted completelyafter 2 min and the melt wasstirredfor 1� h at 2208C. After cooling, the polymericpro-duct P1a was dissolvedin 5 mL DMSO, precipitatedintowater, filtered off anddried at 508C in vacuum.Yield: 2.8g(86%).

1H and 13C NMR dataof the polymerare the sameasforP1c andarelistedthere.

Hydrolysis side product: 1H NMR (DMSO-d6): d = 8.19(NH); 3.49 (HOCH2); 3.29 (1NHCH2); 13C NMR (DMSO-d6): d = 59.81(HOCH2), 42.22(1NHCH2).

Thermalpolymerizationof 4 in solution

a) In tetramethylenesulfone(P1b): 4 (0.93g, 5.1mmol) wasdissolvedin 5 g freshly distilled dry tetramethylenesulfoneat room temperature.Then the flask was placedunderstir-ring into anoil bathpreheatedto 1908C andkeptat this tem-peraturefor 22 h. After cooling, the highly viscousraw pro-duct wasdissolvedin 5 mL DMSO, precipitatedinto water,filtered off and dried at 508C in vacuum. Yield: 0.55g(60%).

1H and 13C NMR dataof the polymerare the sameasforP1c andarelistedthere.

Hydrolysis side product: 1H NMR (DMSO-d6): d = 8.19(NH); 3.49 (HOCH2); 3.29 (1NHCH2); 13C NMR (DMSO-d6): d = 59.81(HOCH2), 42.22(1NHCH2).

b) In N-methylcaprolactam(P1c): A solution of 4 (1.0g,5.58mmol), 3 wt.-% LiCl and 4 g freshly distilled dry N-methylcaprolactamwasstirred25.5h at 1908C. Thepolymer

128 T. Huberet al.

P1c was precipitatedinto water, filtered off and dried at508C in vacuum.Yield: 0.88g (88%). The secondsample(No. 8, Tab.1) waspreparedanalogouslybut with a reactiontime of 24h.

NMR data of P1c, data of P1a and P1b are analogous(assignmentseeFig. 2):

1H NMR (DMSO-d6, 313K): d = 9.64(OHL); 9.40(OHT);8.60(NHD); 8.48(NHL); 8.34(NHT); 7.06(H3D); 6.89(H5L);6.88 (H3L); 6.69 (H1D); 6.69 (H3T); 6.48 (H1L); 6.35 (H1T);4.13(H9D); 4.08(H9L); 3.58(H8).

13C NMR (DMSO-d6, 313K): d = 166.82 (C7T); 166.35(C7L); 165.94(C7D); 159.52(C2D); 159.45(C6L); 158.42(C2L);158.26 (C2T); 136.56 (C4L); 136.44 (C4T); 136.35 (C4D);107.45 (C3L); 106.09 (C3D); 105.50 (C3T); 105.50 (C1D);105.19(C1T); 104.65(C1L); 104.03(C5L); 66.35(C9D); 66.15(C9L); 38.89(C8L); 38.82(C8T); 38.76(C8D).

No signalsof thehydrolysisproductwereobserved.

Resultsand discussion

Synthesisof themonomer

According to a common method for the synthesisof 2-oxazolines29), the AB2 monomer 2-(3,5-dihydroxyphe-nyl)-1,3-oxazoline (4) was synthesizedvia the dehydra-tion of N-2-(hydroxyethyl)-3,5-dihydroxybenzamide (3)using thionyl chloride (Scheme1). The hydroxyamidederivative3 wasobtainedby reactionof 2-ethanolaminewith methyl 3,5-dihydroxybenzoate (2), which wasobtained from the free acid 1 by esterification. Thehydrochloride intermediate of 4 was dissolved in ice-water, and the solution was carefully neutralized withsodiumhydrogencarbonate.Themonomer4 wasreceivedby this procedure in high yield and high purity, thus itcould be used in the polymerization processwithoutfurther purification. The structure and purity of the pro-duct were proven by NMR spectroscopy and elementalanalysis(compareExperimentalpart).

Polymerization of 4

The AB2 monomer4 contains two nucleophilic phenolgroups,which can attack the oxazoline in its 5-positionunderring-opening and step-growth formation of hyper-branched etheramide structures. This reaction wasdescribedby Mulhaupt24) for the preparation of linearpoly(ether amide)sbasedon the AB type monomer2-

(hydroxyphenyl)-2-oxazoline. The ring-opening reactionis thermally induced,andtemperaturesabove themeltingpoint of the monomerare required.The optimization ofthe reaction temperature is very important, since sidereactions,e.g., attackof the formedamideby the oxazo-line,canoccurat high temperatures(cf. Scheme3).

Thethermal ring-opening processof 4 wasstudiedfirstby DSC measurements. Melting wasobserved at 2088C.Immediately after melting a highly exothermic reactionstarted, indicating the nucleophilic attack of the phenolonto the oxazoline group. Therefore, reaction tempera-turesaround2008C or slightly aboveshouldbesufficientfor polymerization. The polymerization of 4 in bulk andin different high boiling solventswere now investigated(Scheme2). Theresults aresummarizedin Tab.1.

The polyaddition reaction in bulk was carried out at2208C for 1.5h. The resulting polymer P1a was white,soluble in dipolar aprotic solventslike DMAc, DMF andDMSO, and exhibited an inherent viscosity in DMF of0.12 dL/g (308C). The 1H NMR spectrumshowed thatsome of the oxazoline groupshydrolyzedbefore nucleo-philic attack of the phenolgroups could take place (cf.Scheme 3). This is indicatedby traces(around1%) of1C(O)NHCH2CH2OH groups in the product (d =8.19 (NH); 3.49 (HOCH2); 3.29 (NCH2)). A detailedquantitativeanalysisof thesidereactionis difficult, sincethesignalsof theexpectedunits andthoseof thesidepro-ducts overlap partially. This side reaction has to be aresult of a smallamountof waterremaining in themono-mer which wasbound very tightly andthereforewasnotremovedby drying in vacuum.

The molar massof P1a asmeasuredby MALD I-TOF-MS was M

—n = 1700g/mol (M

—w/M

—n = 1.2). However, the

GPCanalysisof thesameproductgavea numberaveragemolar massof 22000g/mol (usingPScalibration). Simi-lar deviationsbetweentheresultsfrom MALDI- TOF-MSandGPCwere found for the other polymerssynthesizedin solution. Sincethis largedeviation cannotbeexplainedby differencesin the methodsand also not by the pro-blemsonehasto expect whenhighly branched polymersareanalyzed by GPC(inadequatecalibration with linearstandards),onehasto assumethatno reliableresultswereobtainedby MALD I-TOF-MS. In contrastto perfectden-drimers, hyperbranchedpolymers exhibit a molar massdistribution. It is very likely thatonly thesmallmoleculescould be detected due to differencesin the ionization

Scheme1: Synthesisof themonomer4

Newhyperbranchedpoly(etheramide)svia nucleophilicring openingof 2-oxazoline-containing monomers 129

behavior, the desorption probability, and the stability(possibility of fragmentation) of molecules with differentmolar mass.Therefore, the absolute massand the molarmassdistribution as calculated from the MALD I-TOF-MS spectracannot be trusted for thesehyperbranchedpolymers.

Nevertheless,the analysis of the hyperbranchedpoly-mersby MALDI- TOF-MS is usefulto provethepresence

of the proposedstructure. For low molar massproductslike P1b, it is possibleto resolvein MALD I-TOF-MS thepeaks of themoleculeswith differentdegreesof polymer-ization (Fig. 1). When no side reaction occurred in thepolyreaction, the difference betweenthe peaks shouldcorrespondexactly to the mass of the averagelinearrepeating unit. In our case we found a difference of179.3 Da which is in excellent agreementwith the pro-

Scheme2: Polymerizationof 4 a) in bulk at 2208C andb) in N-methylcaprolactamand3 wt.-% LiCl or in sulfolaneat1908C leadsto the hyperbranchedpolymersP1a–c with oneremainingoxazoline groupasfocal unit. A schematicstruc-tureof P1 andtheaverage repeating unit arepictured

Tab.1. Resultsof thepolymerization of 4, physical dataof thepolymersP1a–c

No. PolymerNo.

Timein h

Medium Temp.in 8C

Color DBa) in % ginh

in dL/gb)Molecularweight Tg

e)

in 8CA B MALDI c) GPCd)

M—

n PDI M—

n PDI

1 P1a 1.5 bulk 220 white 59 44 0.119 1700 1.2 22000 2.3 1752 P1b 4 sulfolane 190 brown 57 40 –f) 1900 1.3 5250 1.9 1753 P1b 8 sulfolane 190 brown 56 40 –f) 1700 1.3 5600 2.1 1734 P1b 30 sulfolane 190 brown 55 41 0.079 1250 1.2 13500 2.6 1705 P1b 25 sulfolane 190 brown 55 41 0.089 –f) –f) 9050 1.6 1766 P1b 23 sulfolane 190 brown 56 47 0.104 2100 1.2 –f) –f) 1737 P1c 24 N-MCLg) 190 brown 51 49 0.121 –f) –f) 25600 2.3 1758 P1c 25.5 N-MCLg) 190 brown 51 50 0.305 –h) –h) 47500 3.6 175

a) Degreeof branchingcalculated A) by Frechet30) andB) by Frey31).b) Inherent viscositymeasuredat 308C with c = 0.2g/dL in dimethylformamide.c) MALD I-TOFmeasurements in 2,5-dihydroxybenzoic acidandtetrahydrofuranmatrix, laserenergy 5.79 lJ.d) GPCmeasurementsin dimethylacetamideat 258C with 3 g/L LiCl and2 vol-% water, polystyrenecalibration.e) DSCmeasurementsat aheating rateof 10K/min.f) Not measured.g) N-MCL = N-methylcaprolactam.h) No signalswereobserved.

130 T. Huberet al.

posedrepeatingunit (Scheme2 andFig. 1). At anintervalof 179Da three peakscan be observed which can beassignedto a protonatedmolecule, to the sodiumadduct,and the most intensive peak to the potassiumadductofthe polymer. However, theseresults can not prove thatthereareno sidereactions or otherrepeatingunits,since,asstatedabove,one can not guarantythat all moleculesfly with thesameprobability .

For the sake of comparison the polymerization wasalsocarriedout in two differentsolvents,tetramethylenesulfone and N-methylcaprolactam,at lower temperature(1908C) but for prolonged reactiontime (Tab.1). Duringpolymerization in tetramethylene sulfone (P1b) thehydrolysisof theoxazoline wasmore pronouncedthaninbulk, which might bean indicationfor thepresenceof anadditionalsmall amountof water in the solvent.After 4to 8 h reactiontime the achieved molar massesasdeter-mined by GPCwereonly M

—n L 5500g/mol with M

—w/M

—n

L 2.0.Extensionof the reaction time to 30 h allowedtheformation of molecules with a molar mass of M

—n

L13500g/mol (GPC). Again, the inherent viscosity ofthe hyperbranchedpolymer P1b (No. 4, Tab.1) in DMFwasvery low with 0.08dL/g (308C). The amountof thehydrolysisproductin thepolymerswasroughly estimatedfrom theprotonNMR spectra(seeabove).About 4 to 5%hydrolysiswasfound for the samplesNo. 2 and3 (lower

molar mass)and about 1.5% in sample No. 4 (highermolar mass). This rough correlation of decreasedachievedmolarmasswith increasedamountof hydrolysissupports our assumption that the hydrolysis limits themolar mass.

Samples were takenduring thepolymerization, andthereaction wasfollowed by 1H NMR over 30h. Besidethehydrolysis,no other sidereactions(cationic ring openingreaction or iminoamideformation), asdescribedby Mul-haupt et al.24) for the linear analogs,couldbeobservedinsulfolane or in bulk for our hyperbranchedpolymers(Scheme3).

During polymerization in N-methylcaprolactam thehydrolysis of the oxazoline group could be suppressed,because a new monomer charge was used which wasdried even more thoroughly (P1c, Fig. 2). The sampleexhibited againa browncolor which mustbeassignedtoside reactions of the solvents,since this coloration wasonly observedwhena solventwasused. For this polymer,a much highermolar masscouldbeachievedafter25.5h,which is indicatedby significantly higherinherentviscos-ities (0.31 dL/g at 308C in DMF) andby GPCmeasure-ments (M

—n = 47500g/mol; M

—w/M

—n = 3.6, sample No. 8).

MALDI-TOF-MS could no longer be applied for thissample. In a secondexperiment with a reactiontime of24 h a molar massM

—n of 25600g/mol with g = 0.121dL/

Fig. 1. MALDI -TOF-MSof P1b (No. 2 in Tab.1; matrix: THF, 2,5-DHB). Thepeakpatternwasverified by additional experimentsusingsodiumandpotassiumsaltsin the matrix. The distancebetween two corresponding peaks(179Da) is in agreement with themassof theaveragelinearrepeatingunit

Newhyperbranchedpoly(etheramide)svia nucleophilicring openingof 2-oxazoline-containing monomers 131

g wasachieved.This strong deviation in molarmasswithonly a small change in the reaction conditions demon-strates how highly dependent the molar massesof ahyperbranchedpolymer are on the achievedconversion.In addition, it also showsthe limit of GPC analysis forhighly branchedpolymers.The solution viscosity valuesfor sample No. 1 (M

—n = 22000) andsample No. 7 (M

—n =

25600) correspondvery well. However, sample 8, with aGPCmolarmassM

—n = 47500showsacomparatively unu-

sual high viscosity (almost threetimes higher comparedto the expectedtwo times). The reason might be that the

measured molar massby GPC differs already stronglyfrom the absolute molar massin this massregime,andthe broader molar massdistribution might havean effecton thesolution viscosities,too. More studieson this poly-merizationsystem, theeffect of thepolymerizationcondi-tionsand,especially, onamorereliablemolar massdeter-minationarein progress.

By using 2D NMR experiments (COSY, HMQC,HMBC), all signalsof the 1H and 13C NMR experimentscould be assignedclearly to the terminal, linearandden-dritic units in the hyperbranched polymer P1c (Tab. 2

Scheme3: Possiblesidereactionsof theoxazolinegroup

Fig. 2. 1H NMR spectra of P1c. 1H-1H COSY, 1H-13C HMBC and 1H-13C HMQC experiments wereconductedto assignthesignalsto the threedifferentunits in thepolymer (seeTab.2 and3). Thezoomedpartshowsa peakintegrationratio of1:2:1 (dendritic : linear: terminalunit) accordingto theexpectedratio of a statisticalreaction (DB = 50%)

132 T. Huberet al.

and3). This allowedit to provethestructureandto calcu-late the degree of branchingDB (Fig. 2, Tab. 1). Usingthe classical equation for the degreeof branching asdefinedby Frechet30) (dendritic andterminal unitsdividedby all units)a DB of 51%andby the methodof Frey31) aDB of 50% were calculated. Thesevaluesare in goodagreement with a statistical polyreaction without anydif-ferencesin the reactivity of the two phenol groups. Asexpected, a larger deviation in the DB calculated by thetwo differentmethodswasobtainedfor the sampleswithlower molar mass,sincetheequationby Frechetoveresti-matestheDB at a low degreeof polymerization.

All hyperbranchedpolymersP1 exhibited glasstransi-tion temperaturesfrom 170 to 1768C (DSC) anddecom-posed at temperaturesabove3308C.

ConclusionsIt could be demonstratedthat the nucleophilic ring-open-ing reaction can be usedvery successfully to synthesizehyperbranched poly(ether amide)s. The polymerizationproceedsin a statistical way when side reactions can besuppressed.MALDI-TOF-MSmeasurementsconfirm themassof the average repeatingunit and exclude majorside reactions, but cannot give reliable results on theabsolute molar mass.Tendencies in molar masscan bewell estimatedby GPCmeasurementandthe increaseinthe inherent viscositiesof the polymers.With 2D NMRexperimentsthe structureand the different units of thehyperbranched polymers could be identified, and thedegree of branching was calculatedto be approximately50%. Theobtainedpolymersbeara very largenumberoffunctionalgroupsandexhibit excellent solubility andlowsolution viscositiesbecauseof their highly polar structureand their amidic junctions. In further experiments, thereactivity of the functional groups, and especially themelt viscositiesas well as the mechanical propertiesofthesenew hyperbranched polymers will be studied. Inaddition, with the experienceswe obtainedusing mono-mer 4 for the thermal nucleophilic ring-openingreactionwe startedto extend the structureversatility to hyper-branchedpoly(esteramides)and to hyperbranchedpoly-amideswith carboxylic acidor oxazoline endgroups.

Acknowledgements:ThomasHuberwould like to thankDr. G.Pompe for DSC,thermalanalysismeasurements,andfor helpfuldiscussions.The financial supportby Deutsche Forschungsge-meinschaftis gratefully acknowledged.Juraj Kronek acknowl-edgesthe Slovakgrant agencyVEGA(projectno. 4004/97)andthe Fund for international cooperation of the GermanFederalMinistry for Education,ScienceResearch and Technology (pro-ject no.X292.91).

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Tab. 2. HMQC 1JCH correlation of P1c, coordinates of thecrosspeakswith assignmentto thedifferentunits(cf. Fig. 2)

HMQC 1JCH correlation1H (ppm) 13C (ppm) assignmenta)

9.64 – LOH

9.48 – TOH

8.6 – DNH

8.48 – LNH

8.34 – TNH

7.06 106.09 3D6.89 104.65 5L6.88 107.45 3L6.69 105.50 3T6.69 103.85 1D6.48

104.651L

6.35 105.19 1T4.13 66.35 9D4.09 66.15 9L3.58 38.82 8

a) Abbreviation of the assignment refersto the units showninFig. 2.

Tab. 3. HMBC 3JCH correlation of P1c, coordinatesof thecrosspeakswith assignmentto thedifferentunits(cf. Fig. 2)

HMBC 3JCH coherence1H (ppm) 13C (ppm) assignmenta)

9.64 – LOH

9.48 – TOH

8.6 – DNH

8.48 – LNH

8.34 – TNH

7.06 165.94,106.09,103.85 3De 7D, 3D, 1D6.89 166.35,107.45,104.65 5L e 7L, 3L, 1L6.88 166.35,104.65,104.03 3L e 7L, 1L, 5L6.69 166.35,105.50,105.19 3T e 7T, 3T, 1T6.69 106.09 1De 3D6.48 107.45,104.03 1L e 3L, 5L6.35 105.50 1T e 3T4.13 159.52 9De 2D4.09 159.45 9L e 6L3.58 38.82 8

a) Abbreviation of the assignment refersto the units showninFig. 2.

Newhyperbranchedpoly(etheramide)svia nucleophilicring openingof 2-oxazoline-containing monomers 133

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