Synthesis and characterization of water-soluble hyperbranched poly(ester amine)s from diacrylates...

Synthesis and Characterization of Water-SolubleHyperbranched Poly(ester amine)s from Diacrylatesand Diamines

CHAO GAO, WEI TANG, DEYUE YAN

College of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road,Shanghai 200240, People’s Republic of China

Received 4 January 2002; accepted 19 April 2002Published online 00 Month 2002 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/pola.10322

ABSTRACT: Various water-soluble hyperbranched poly(ester amine)s were synthesizedby the direct polyaddition of diamines to diacrylates in the absence of a catalyst. Eachdiamine contained a secondary amino group and a primary amino group such as1-(2-aminoethyl)piperazine, N-methyl-1,3-propanediamine, or N-ethylethylenedia-mine. When the ratio of diacrylate to diamine was 1/1, no gelation was observedthroughout the polymerization. When the ratio of diacrylate to diamine was 3/2, nocrosslinking occurred in the diluted solution, whereas an insoluble network formed inthe concentrated solution. Fourier transform infrared and mass spectrometry wereused to investigate the reaction procedure. The secondary amino group of diaminereacted faster with the vinyl group of diacrylate; this resulted in the formation of theintermediate with an acrylate group and two active hydrogen atoms attached to anitrogen atom. Further self-polyaddition of the intermediate, a kind of AB2-type mono-mer, gave the hyperbranched poly(ester amine). © 2002 Wiley Periodicals, Inc. J Polym SciPart A: Polym Chem 40: 2340–2349, 2002Keywords: addition polymerization; diacrylates; diamines; hyperbranched; poly-amines; polyesters; water-soluble polymers

INTRODUCTION

Hyperbranched polymers have earned a reputa-tion for their unique features, including high sol-ubility, low viscosity, and good rheological behav-ior.1–4 Most hyperbranched polymers are pre-pared through the polymerization of one type ofmonomer. Recently, the one-step polymerizationof two or more types of monomers for hyper-branched polymers has been receiving more andmore attention because of its simplicity and con-venience. Kakimoto et al.5 synthesized hyper-branched aromatic polyamides by the direct poly-condensation of aromatic diamines (A2) and tri-

mesic acid (B3) in the presence of a catalyst.Through the A2 � B3 approach, Frechet et al.6

obtained hyperbranched aliphatic polyethers. Bycontrolling the feed ratio of triamine (B3) to dian-hydride monomers (A2), Okamoto et al.7 preparedwholly aromatic hyperbranched polyimides thatcould be applied to gas separation. It is wellknown that the polycondensation of A2 and B3

monomers generally results in gelation.8 There-fore, we present the A2 � BB�2 approach to hy-perbranched polymers, which is based on the non-reactivity of different functional groups.9,10 In theBB�2-type monomer, there are one B functionalgroup and two B� functional group. The reactivityof B is much higher than that of B�; this results inthe predominant formation of AB�2-type interme-diates in the initial stage of the reaction. There-fore, crosslinking can be avoided in this A2 � BB�2

approach.

Correspondence to: D. Yan (E-mail: [email protected])Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 40, 2340–2349 (2002)© 2002 Wiley Periodicals, Inc.

2340

In this study, the Michael addition of a mono-mer with a secondary amino group and a primaryamino group (BB�2) to a divinyl monomer (A2) ledto water-soluble hyperbranched poly(esteramine)s. Michael addition has been widely usedin the synthesis of dendritic polymers, includingthe famous poly(amidoamine) PAMAM dendrim-ers11 and poly(propyl imine) dendrimers (DAB-dendr-NH2).12 Recently, an excellent hyper-branched polymer-related work pioneered byFeast and coworkers13,14 was published. In theirwork, a series of AB2 aminoacrylate hydrochlo-ride monomers (where A represents a Michaelacceptor and B2 represents a primary aliphaticamine) were first synthesized. Further self-addi-tion of the AB2 monomers led to the generation ofpoly(amidoamine) hyperbranched materials, ex-amples of which exhibited a branching factor [de-gree of branching (DB)] close to 1.13,14 Other typesof addition reactions have also been adopted inthe fabrication of hyperbranched polymers.15

As a new class of degradable, functional mate-rials hyperbranched polyesters have received in-creasing attention.16–18 Aromatic hyperbranchedpolyesters can be prepared by the polycondensa-tion of various AB2-type monomers such as3,5-bis(trimethylsiloxy)-benzoyl chloride,19–23 bis-(trimethylsilyl)-5-acetoxy-isophthalate,24 5-(2-hy-droxyethoxy) isophthalic acid,25 4,4-bis(4�-hy-droxyphenyl)-pentanoic acid,26 4,5-dichloroph-thalic acid,27 and their derivatives.28,29 Throughthe palladium-catalyzed carbon monoxide inser-tion reaction, Kakimoto et al.30 obtained aromatichyperbranched polyesters by the polymerizationof 3,5-dibromophenol and 5-bromoresorcinol or5-iodoresorcinol. Hult and coworkers31–37 didmuch work on aliphatic hyperbranched polyestersbased on 2,2-bis(hydroxymethyl)propionic acid.Matyjaszewski et al.38 synthesized hyperbranchedpolyacrylates by the atom transfer radical poly-merization of an AB*-type monomer, 2-[(2-bro-mopropionyl)oxy]ethyl acrylate, with a copper(I)/copper(II) catalyst system. Via the ring-openingpolymerization of �-caprolactone, L-lactide, orsubstituted lactones with the benzyl ester of 2,2�-bis(hydroxymethyl)-propionic acid as an initiator,Hedrik and coworkers39,40 made degradable ali-phatic block branched copolyesters. However, hy-perbranched polyesters are generally insoluble inwater without further modification;41 this limitstheir application fields, especially in drug deliv-ery, gene delivery, and macromolecular buildingblocks.42 This work reports the synthesis of aseries of water-soluble hyperbranched poly(esteramine)s via A2 � BB�2 approach.

EXPERIMENTAL

Materials

The monomers 1-(2-aminoethyl)piperazine (AP),N-ethylethylenediamine (NDA), N-methyl-1,3-propanediamine (NPA), 4-(aminomethyl)piperi-dine (AMP), piperazine (PZ), and poly(ethylglycol) diacrylate [PEODA; CH2ACHCOO(CH2-CH2O)nOCCHACH2, where n � 6, 8, or 14] werepurchased from Aldrich and used as received.Ethylene diacrylate (EDA) was purchased fromMonomer–Polymer & Dajac Labs, Inc., and wasused without further purification. The solventschloroform, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-methyl-2-pyrroli-done (NMP), and dimethyl sulfoxide (DMSO)were purchased from domestic chemical marketsand purified by vacuum distillation before use.Methanol, acetone, and hydrochloric acid werealso purchased from domestic chemical marketsand used as received.

Measurements

Fourier transform infrared (FTIR) measurementswere performed on a Bruker Equinox 55 spec-trometer with a Barnes analytical FTIR sealedcell (KBr, 0.5 mm), and chloroform was used as asolvent. 1H NMR was recorded with a 500-MHzBruker NMR model, tetramethylsilane was usedas the internal standard in all cases, and D2O wasused as the solvent. Mass spectra were obtainedon an HP 1100 liquid chromatography/mass spec-trum detector; the conditions of the spray cham-ber were as follows: polarity, positive; ionizationmode, APCI; fragmentor, 70 v; nebulizer pres-sure, 60 psig; drying gas flow, 7.0 mL/min; anddrying gas temperature, 325 °C. The tested sam-ple taken from the reaction system during theinitial reaction period was protected by 2 N aque-ous hydrochloric acid as soon as it was taken fromthe reaction mixture. The molecular weight of theproduct was obtained on an HP 1100 gel perme-ation chromatograph with water as a solvent andpoly(ethylene oxide) (PEO) as a standard, and thecolumn used was G6000 PW (XL). Thermogravi-metric analysis was performed under nitrogen ona PE Pyris-7 thermal analyzer. All samples wereheated at 20 °C/min heating rates from 25 to 650°C. Differential scanning calorimetry (DSC) stud-ies were conducted under nitrogen on a PEPyris-1 DSC thermal analyzer. All samples wereheated at a 20 °C/min heating rate from �80 to150 °C.

HYPERBRANCHED POLY(ESTER AMINE)S 2341

Poly(EDA-AP) Synthesis

A typical preparation example is given as follows.EDA (5.1048 g, 30 mmol) was added to a solutionof AP (3.8763 g, 30 mmol) in 20 mL of chloroform.The mixture was kept at 40 °C for 120 h andpoured into a mixture of 500 mL of acetone and 20mL of aqueous HCl (8 M). The precipitate waswashed with acetone and collected.

Yield: 8.5 g. FTIR (KBr): 3450–3250 (ONH2 orONH), 1730 cm�1 (CAO). 1H NMR (500 MHz,D2O): 4.25 (CH2O), 3.65 [(CH2)3N], 3.45 (CH2NH),3.15 (CH2NH2).

Poly(PEODA-6-AP) Synthesis

A typical synthesis example is given as follows.PEODA-6 (20 mmol) in 15 mL of chloroform wasadded dropwise to a solution of AP (2.5842 g, 20mmol) in 15 mL of chloroform. The mixture waskept at 35 °C for 150 h and poured into a mixtureof 600 mL of acetone and 20 mL of aqueous HCl (8M). The precipitate was washed with acetone andcollected.

Yield: 6.5 g. FTIR (KBr): 3450–3250 (ONH2 orONH), 1725 (CAO), 1105 cm�1 (CH2O). 1H NMR(500 MHz, D2O): 4.25 (CH2O), 3.60 [(CH2)3N],3.45 (CH2NH), 3.15 (CH2NH2).

Poly(EDA-NDA)

IR (KBr): 3450–3250 (ONH2 or ONH), 1729.5cm�1 (CAO). 1H NMR (500 MHz, D2O): 4.28

(CH2O), 3.55 [(CH2)3N], 3.48 (CH2NH), 3.18(CH2NH2), 1.22 (CH3).

Poly(EDA-NPA)

IR (KBr): 3450–3250 (ONH2 or ONH), 1731cm�1 (CAO). 1H NMR (500 MHz, D2O): 4.30(CH2O), 3.55 [(CH2)3N], 3.35 (CH2NH), 3.21(CH2NH2).

Poly(EDA-AMP)

IR (KBr): 3450–3250 (ONH2 or ONH), 1725.5cm�1 (CAO). 1H NMR (500 MHz, D2O): 4.28(CH2O), 3.51 [(CH2)3N], 3.28 (CH2NH), 3.15(CH2NH2), 1.35 (CH2).

Poly(PEODA-8-AP)

IR (KBr): 3450–3250 (ONH2 or ONH), 1722(CAO), 1115 cm�1 (CH2O). 1H NMR (500 MHz,D2O): 4.25 (CH2O), 3.50 [(CH2)3N], 3.31(CH2NH), 3.22 (CH2NH2).

Poly(PEODA-14-AP)


Scheme 1. Selection of the monomers for the synthesis of the water-soluble hyper-branched poly(ester amine).

2342 GAO, TANG, AND YAN

Poly(PEODA-8-NDA)

IR (KBr): 3450–3250 (ONH2 or ONH), 1725(CAO), 1110 cm�1 (CH2O). 1H NMR (500 MHz,D2O): 4.28 (CH2O), 3.52 [(CH2)3N], 3.31(CH2NH), 3.18 (CH2NH2), 1.25 (CH3).

Poly(PEODA-8-NPA)


Poly(PEODA-8-AMP)

IR (KBr): 3450–3250 (ONH2 or ONH), 1725(CAO), 1115 cm�1 (CH2O). 1H NMR (500 MHz,D2O): 4.25 (CH2O), 3.52 [(CH2)3N], 3.31(CH2NH), 3.18, (CH2NH2), 1.35 (CH2).

Poly(EDA-PZ)1H NMR (500 MHz, D2O): 4.15, 3.91, 3.55, 3.32,2.7, 2.65, 1.88.

RESULTS AND DISCUSSION

Selection of the Monomers

For the improvement of the water solubility of theresulting hyperbranched polyester, amino groupswere considered as partial units in the macromo-lecular backbones. However, the polycondensa-tion of A2 and B4 would generally result incrosslinking.8 Therefore, each diamine chosen inthis work contains a secondary amino group and aprimary one. In nucleophilic addition, the reactiv-ity of the hydrogen atom of a secondary aminogroup is greater than that of hydrogen atomslinked to primary amino groups because of thestronger electrophobic influence of the alkylgroup attached to the secondary nitrogen at-om.9,10,43,44 Therefore, the diamine monomer iscalled as BB�2. Diacrylate with two double bondsis called A2. Scheme 1 displays the selection of themonomers for this approach. The B group of BB�2reacts faster with the A group of A2, generatingan AB�2-type intermediate that can be self-con-densed to produce the hyperbranched polymer. Inthe meantime, the formed AB�2 would covalentlycouple with BB�2 to provide molecule 5. Species 5with four B�’s can play the role of the core mole-cule,45,46 leading to the narrow molecular weightdistribution of the hyperbranched polymer.

The approach is versatile because many so-called diacrylates and diamines can be used tosynthesize water-soluble hyperbranched poly(es-ter amine)s. If diacrylates containing poly(ethylglycol) units are used to react with either of theBB�2 monomers, hyperbranched poly(ester etheramine) can be fabricated.

In Situ FTIR Characterization

The reaction progress was first examined with insitu FTIR spectroscopy. With the reaction, theabsorption peak of secondary amino groups at3334 cm�1 and the peaks of vinyl groups at 1636and 1616 cm�1 rapidly decrease, and at about 3 h,the former disappears and the latter decrease toabout half of the original area [Fig. 1(A)]. Duringthis period, the peaks of primary amino group at3383 and 3306 cm�1 change little. These dataindicate that the reactivity of secondary aminogroups is indeed much higher than that of pri-mary groups, and the dominant reaction in the

Figure 1. In situ FTIR spectra of the reaction systemof EDA and AP in a 1/1 ratio (A) during the initial 3 hand (B) from 3 to 72 h.


first stage is the addition of a secondary aminogroup to the double bond. Then, the absorptionband of primary amino groups gradually de-creases with the decrease in the absorption ofdouble bonds, and the peaks of the primary aminogroup still appear in the spectrum when those ofdouble bonds vanish [Fig. 1(B)]. The result showsthat the primary amino groups further react withthe residual vinyl groups to form a branched poly-mer with primary amino end groups. The outcomethat resulted from the FTIR characterization is ingood agreement with the prediction of the reac-tion progress between A2 and BB�2 monomers.

The same results can be obtained from thereaction systems of other monomers.

Analysis of the Mass Spectra

From in situ FTIR spectra, the whole reactionprocedure was observed, but molecules 3 and 5cannot be seen. To resolve this problem, we needa mass spectrum of the reaction mixture takenfrom the polymerization system at the initialstage. Figure 2 shows the mass spectrum for thereaction mixture of EDA and AP at 3 h. Theformed molecules can be deduced from the corre-

Figure 2. Mass spectrum for the reaction mixture of EDA and AP at 3 h.


sponding m/z, and then the initial reaction pathsare known. Schemes 2 and 3 display the dominantreaction path and other reaction paths, respec-tively. AB�2 (3) and its dimer (7) and trimer (101)are observed as peaks at m/z � 300.4, 599.8, and899.2, respectively. The molecular ion peak ofmolecule 5 is also observed at m/z � 429.5. Ananalysis of mass spectra for other reaction sys-tems also shows the same results.

Polymer Synthesis

The initial molar ratio of A2 to BB�2 is set at 1/1and 3/2. Some reaction conditions and results arelisted in Table 1. Chloroform is a good solvent forthe polymerization in which the hyperbranchedpoly(ester amine) with the highest molecularweight is prepared. No considerable distinction inthe molecular weight was observed when strongpolar solvents such as DMSO, DMA, DMF, andNMP were used as solvents. If the reaction wascarried out in water, the molecular weight of theproduction was not as high as that of those pre-pared in the organic solvents. This phenomenonmight have resulted from the degradation of theester units in water. The molecular weight distri-bution shown in Table 1 is very narrow (Mw/Mn� 1.4); this can be attributed to the formation ofcore molecules in the reaction system and theremoval of low molecular weight products duringthe reprecipitation. The resulting polymer isquite soluble in water (solubility � 0.35 g/mL).

The temperature has a significant influence onthe polymerization at the same reaction time (60h). The molecular weight of the resulting polymer

increases below 80 °C and then slightly decreaseswith the reaction temperature increasing above80 °C (Fig. 3); this might be caused by the higherDB of the resulting polymer or the side reactionbetween ester units and amino groups. When thefeed ratio of the A2 monomer to the BB�2 mono-mer is 1/1 (A/B/B� � 2/1/2), no crosslinking ap-pears in the polymerization. When the feed ratioof A2 to BB�2 is 3/2 (A/B/B� � 3/1/2), no gelationcan be observed in a diluted solution at a lowtemperature, and an insoluble network is easilyformed in a concentrated solution at a high tem-perature. Figure 4 displays the relationship be-tween the time of gelation and the reaction tem-perature. When the temperature is lower than 40°C, crosslinking cannot be observed even through30 days of reaction. For the reaction system of A2and B3 monomers, soluble hyperbranched poly-mers can be obtained only when the feed ratio ofA2 to B3 is 1/1 (A/B � 2/3) in the presence of aspecial catalyst.11,12 No successful example wasreported when the feed ratio of A2 to B3 was 3/2(A/B � 1/1), except that the product was precipi-tated or end-capped before crosslinking.2

The effect of the reaction time on the polymer-ization is also given in Figure 3 (the correspond-ing reaction temperature is 40 °C). The molecularweight increases considerably with increasing re-action time, and after 60 h, the molecular weightincrease is negligible. In our experiments, thereaction time was set at 100–150 h so that thevinyl groups were totally reacted.

Figure 5 shows the influence of the concentra-tion on the polymerization. When the concentra-tion is higher than 1.8 mol/L, the molecular

Scheme 2. Dominant reaction path for EDA and AP monomers.


weight decreases slightly. However, the yield ofthe resulting polymer increases with increasingmonomer concentration.

The glass-transition temperature (Tg) of thehyperbranched polymers made from EDA anddiamines is 35– 45 °C, and Tg of the polymers

Scheme 3. Other reaction paths for EDA and AP monomers.

Table 1. Reaction Conditions and Results of the Polymerization of EDA and AP

Code A2/BB�2 A/B/B� Solvent Time (h) Yield (%) DB (%) Mw Mw/Mn

PEA-01 1/1 2/1/2 DMSO 120 90.8 62.5 18,500 1.32PEA-02 1/1 2/1/2 DMA 120 89.5 58.3 17,340 1.28PEA-03 1/1 2/1/2 CHCl3 120 91.5 63.8 20,300 1.29PEA-04 1/1 2/1/2 DMF 120 90.2 18,450 1.30PEA-05 1/1 2/1/2 NMP 120 85.4 15,680 1.33PEA-06 3/2 3/1/2 CHCl3 150 92.7 75.5 21,360 1.35PEA-07 3/2 3/1/2 DMSO 150 85.4 73.6 17,580 1.38


with PEODA is 15–25 °C lower; this can beattributed to their flexible carbon– oxygenbonds.

DB

DB is defined as the ratio of branched units (Nb)and terminal units (Nt) to the total units (Nb � Nt� Nl).

19,47–49 DB of the resulting hyperbranchedpoly(ester amine)s was determined by 1H NMR.For the hyperbranched polymers reported here,the number of linear units is equal to the numberof secondary amino groups (CH2NHCH2), and thenumber of terminal units is equal to the numberof primary amino groups (CH2NH2). Further-more, the protons of ethylene of CH2NHCH2 or

CH2NH2 can be assigned independently (Fig. 6).For the hyperbranched polymer, Nt � Nb � 1.Then,

DB � �Nb � Nt�/�Nb � Nt � Nl� � �2Nt � 1�

� �2Nt � Nl � 1� � 1/�1 � Nl/2Nt) (1)

Because the ratio of Nl/Nt can be calculated fromthe integration ratio of the corresponding peaks,DB can be determined. DB of the hyperbranchedpoly(ester amine)s is shown in Table 1. DB ishigher than 50%, which resulted from the non-equal reactivities of secondary and primary

Figure 3. Influence of the reaction temperature ortime on the polymerization of EDA with AP.

Figure 4. Gelation time for the polymerization ofEDA and AP in a 3/2 ratio as a function of the reactiontemperature.

Figure 5. Influence of the concentration of the EDAmonomer on the polymerization of EDA and AP.

Figure 6. 1H NMR spectra of (A) linear poly(EDA-PZ) and (B) hyperbranched poly(EDA-AP).


amino groups.9,10,13,14 The maximum DB for ahyperbranched polymer made from an AB2-typemonomer with two equal-reactivity groups of B is50%.47–49 In this study, a vinyl group reactedwith a primary amino group and resulted in asecondary amino group that was more reactivethan the primary amino one. Therefore, DB of thehyperbranched poly(ester amine)s is higher than50%. Feast and coworkers13,14 reported that thehyperbranched poly(amidoamine) prepared bythe melting polymerization of AB2 aminoacrylatehydrochloride monomers had a DB close to 100%.

CONCLUSION

The A2 � BB�2 approach to hyperbranched poly-mers was successfully applied to the preparationof hyperbranched polyesters with end aminogroups. Because numerous amino groups wereintroduced into the backbones of the polyester,the resulting hyperbranched macromoleculeswere quite soluble in water. The analysis of insitu FTIR and mass spectrometry showed that thereaction paths were fully in agreement with theprediction of the reaction between A2 and BB�2monomers. Because of the higher reactivity ofsecondary amino groups, an intermediate with adouble bond and two active hydrogen atoms and afew molecules with multiple amino groups weregenerated in the reaction system, so hyper-branched polymers with narrower molecularweight distributions were synthesized without ge-lation.

This work was sponsored by the National Natural Sci-ence Foundation of China (29974017) and W. L. Gore &Associate, Inc. (United States). The authors thank Mrs.Pinfang Chu and Ping Tao of the Analytical Instrumen-tal Center at Shanghai Jiao Tong University for theFTIR and LC/MSD measurements.

REFERENCES AND NOTES

1. Kim, Y. H.; Webster, O. W. J Am Chem Soc 1990,112, 4592.

2. Voit, B. I. J Polym Sci Part A: Polym Chem 2000,38, 2505.

3. Kim, Y. H. J Polym Sci Part A: Polym Chem 1998,36, 1685.

4. Frechet, J. M. J.; Hawker, C. J.; Gitsov, I.; Leon,J. W. J Macromol Sci Pure Appl Chem 1996, 33,1399.

5. Jikei, M.; Chon, S.; Kakimoto, M.; Kawauchi, S.;Imase, T.; Watanebe, J. Macromolecules 1999, 32,2061.

6. Emrick, T.; Chang, H.; Frechet, J. M. J. Macromol-ecules 1999, 32, 6380.

7. Fang, J.; Kita, H.; Okamoto, K. Macromolecules2000, 33, 4639.

8. Flory, P. J. J Am Chem Soc 1941, 63, 3083.9. Gao, C.; Yan, D. Y. Chem Commun 2001, 107.

10. Yan, D. Y.; Gao, C. Macromolecules 2000, 33, 7693.11. Tomalia, D. A.; Baker, H.; Dewald, J.; Hall, M.;

Kallos, G.; Martin, S.; Roeck, J.; Ryder, J.; Smith,P. Polym J 1985, 17, 117.

12. Buhleier, E.; Wehner, W.; Vogtle, F. Synthesis1978, 155.

13. Hobson, L. J.; Kenwright, A. M.; Feast, W. J. ChemCommun 1997, 1877.

14. Hobson, L. J.; Feast, W. J. Polymer 1999, 40, 1279.15. Harrison, R. M.; Feast, W. J. Am Chem Soc Polym

Mater Sci Eng 1997, 77, 162.16. Johansson, M.; Malmstrom, E.; Hult, A. TRIP

1996, 4, 398.17. Malmstrom, E.; Johansson, M.; Hult, A. Polym

News 1997, 22, 128.18. Malmstrom, E.; Hult, A. J Macromol Sci Rev Mac-

romol Chem Phys 1997, 37, 555.19. Hawker, C. J.; Lee, R.; Frechet, J. M. J. J Am Chem

Soc 1991, 113, 4583.20. Wooley, K. L.; Frechet, J. M. J.; Hawker, C. J.

Polymer 1994, 35, 4489.21. Wooley, K. L.; Hawker, C. J.; Lee, R.; Frechet,

J. M. J. Polym J 1994, 25, 187.22. Kricheldorf, H. R.; Bolender, O.; Wollheim, T. Mac-

romolecules 1999, 32, 3878.23. Turner, R. S.; Voit, B. I.; Mourey, T. H. Macromol-

ecules 1993, 26, 4617.24. Kricheldorf, H. R.; Stober, O. Macromol Rapid

Commun 1994, 15, 87.25. Turner, S. R.; Walter, F.; Voit, B. I.; Mourey, T. H.

Macromolecules 1994, 27, 1611.26. Kambouris, P.; Hawker, C. J. J Chem Soc Perkin

Trans 1 1993, 2717.27. Kricheldorf, H. R.; Bolender, O.; Wollheim, T. High

Perform Polym 1998, 10, 217.28. Feast, W. J.; Stainton, N. M. J Mater Chem 1995,

5, 405.29. Kricheldorf, H. R.; Stukenbrock, T. Polymer 1997,

38, 3373.30. Ishida, T.; Jikei, M.; Kakimoto, M. Polym Adv

Technol 2000, 11, 698.31. Malmstrom, E.; Hult, A. Macromolecules 1996, 29,

1222.32. Malmstrom, E.; Johansson, M.; Hult, A. Macromol-

ecules 1995, 28, 1698.33. Johansson, M.; Hult, A. J Coat Technol 1995, 67,

35.34. Hult, A.; Johansson, M.; Malmstrom, E. Macromol

Symp 1995, 98, 1159.35. Malmstrom, E.; Liu, F.; Boyd, R. H.; Hult, A.;

Gedde, U. W. Polym Bull 1994, 32, 679.


36. Johansson, M.; Malmstrom, E. Hult, A. J Polym SciPart A: Polym Chem 1993, 31, 619.

37. Magnusson, H.; Malmstrom, E.; Hult, A. Macro-molecules 2000, 33, 3099.

38. Matyjaszewski, K.; Gaynor, S. G.; Kulfan, A.; Pod-wika, M. Macromolecules 1997, 30, 5192.

39. Trollsås, M.; Kelly, M. A.; Claesson, H.; Siemens,R.; Hedrik, J. L. Macromolecules 1999, 32, 4917.

40. Trollsås, M.; Hedrik, J. L. Macromolecules 1998,31, 4390.

41. Turner, S. R.; Voit, B. I.; Walter, F. Polym MaterSci Eng 1993, 68, 57.

42. Uhrich, K. TRIP 1997, 5, 388.

43. McDowell, S. T.; Stirling, C. J. M. J Chem Soc B1967, 343.

44. McDowell, S. T.; Stirling, C. J. M. J Chem Soc B1967, 348.

45. Hanselmann, R.; Holter, D.; Frey, H. Macromole-cules 1998, 31, 3790.

46. Yan, D. Y.; Zhou, Z. P. Macromolecules 1999, 32,819.

47. Holter, D.; Frey, H. Acta Polym 1997, 48, 298.48. Yan, D. Y.; Muller, A. H. E.; Matyjaszewski, K.

Macromolecules 1997, 30, 7024.49. Holter, D.; Burgath, A.; Frey, H. Acta Polym 1997,

48, 30.


Synthesis and characterization of water-soluble hyperbranched poly(ester amine)s from diacrylates...

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