Novel Antibacterial Polyglycidols: Relationship between Structure and Properties

19 Pages·2017·1.92 MB·English

polymers
Article
Novel Antibacterial Polyglycidols: Relationship
between Structure and Properties
FabianMarquardt,CorneliaStöcker,RitaGartzen,ElisabethHeine,HelmutKeul*
andMartinMöller*
InstituteofTechnicalandMacromolecularChemistry,RWTHAachenUniversityandDWILeibniz-Institutefor
InteractiveMaterials,Forckenbeckstr.50,D-52056Aachen,Germany;[email protected](F.M.);
[email protected](C.S.);[email protected](R.G.);[email protected](E.H.)
* Correspondence:[email protected](H.K.);[email protected](M.M.)
Received:4December2017;Accepted:18January2018;Published:20January2018
Abstract:Antimicrobialpolymersareanattractivealternativetolowmolecularweightbiocides,because
theyarenon-volatile,chemicallystable,andcanbeusedasnon-releasingadditives. Polymerswith
pendantquaternaryammoniumgroupsandhydrophobicchainsexhibitantimicrobialproperties
duetotheelectrostaticinteractionbetweenpolymerandcellwall, andthemembranedisruptive
capabilitiesofthehydrophobicmoiety. Herein,thesynthesisofcationic–hydrophobicpolyglycidols
with varying structures by post-polymerization modification is presented. The antimicrobial
propertiesofthepreparedpolyglycidolsagainstE.coliandS.aureusareexamined. Polyglycidol
with statistically distributed cationic and hydrophobic groups (cationic–hydrophobic balance
of 1:1) is compared to (i) polyglycidol with a hydrophilic modification at the cationic
functionality;(ii)polyglycidolwithboth—cationicandhydrophobicgroups—ateveryrepeatingunit;
and(iii)polyglycidolwithacationic–hydrophobicbalanceof1:2. Arelationshipbetweenstructure
andpropertiesispresented.
Keywords:antimicrobialpolymers;functionalpolyethers;structure-propertyrelationship;multifunctional
polyglycidol;post-polymerizationfunctionalization
1. Introduction
Contaminationbymicroorganismssuchasbacteria,fungi,andalgaeisakeyissueinmedicine[1],
pharmaceutical production [2], water purification systems [3], food packaging [4], and various
other fields [5,6]. Artificial materials lack defense against microbial growth, allowing microbes
to attach to the surface and form a biofilm [7]. One way to prevent the biofilm formation is the
usage of disinfectants to keep the surface sterile. Common disinfectants include low molecular
weightsubstancessuchasalcohols,aldehydes,quaternaryammoniumcompounds,silvercompounds,
peroxygens,andbisphenols[8]. However,theseclassesofantimicrobialsubstancesneedtobeapplied
regularly,leadingtothedevelopmentofresistanceinthemicrobialstrains[9]. Anotherwaytoprevent
microbialgrowthisthecoatingofsurfaceswithantimicrobialsubstancesthateitherkillmicroorganisms
oncontactorrepeltheattachmentofmicrobes[10]. Nevertheless,theleachingofbiocidesfromthose
coatingscausesthesamepreviouslymentionedproblems. Anattractivealternativetolowmolecular
weightbiocidesareantimicrobialpolymers,becausetheyarenon-volatile,chemicallystable,andcan
beusedasnon-releasingadditives[11]. Thesepolymersarepreparedeitherby(co-)polymerizationof
functionalizedmonomersorbypost-polymerizationfunctionalization[12]. Though,theantimicrobial
propertiesarederivedfromavarietyoffunctionalitiessuchasbiguanides[13,14], benzoateesters
and benzaldehydes [15], or poly(acrylic acid) [16], the most common active moieties are based on
a combination of quaternary ammonium, pyridinium, or phosphonium groups and hydrophobic
functionalities[17–19]. Theproposedandcommonlyacceptedmechanismforthesetypesofpolymers
Polymers2018,10,96;doi:10.3390/polym10010096 www.mdpi.com/journal/polymers
Polymers2018,10,96 2of19
features the electrostatic interaction between the cationic moieties and the negatively charged
bacterial cell membrane and the disruption of the cell membrane by the hydrophobic groups,
leading to leakage and, subsequently, cell death [20,21]. However, due to the heterogeneity and
bacterial strain specificity of the cell wall composition, the efficacy of antimicrobial polymers is
species-dependent. TheouterpartofthecellwallofGram-positivebacteriaiscomposedofabout
90%peptidoglycan. InGram-negativebacteria,thepeptidoglycanlayeraccountsforapproximately
20%ofthecellenvelope,beinglocatedbetweentheoutermembraneandinnercellmembrane. Before
reaching the inner cell membrane, polymers interact with the negatively charged components of
the outer part of the bacterial cell envelope, e.g., teichoic acids in the thick peptidoglycan layers
of Gram-positive bacteria, and phospholipids and lipopolysaccharides in the outer membrane of
Gram-negativebacteria[22,23]. Theeffectivenessoftheantimicrobialcationic–hydrophobicpolymers
isdependentonvariousfactors[24]. Onefactoristhemolecularweightofthepolymer. Ikedaetal.
synthesized polymethacrylates with pendant biguanide units and various molecular weights and
testedtheantimicrobialactivityagainstStaphylococcusaureus,reachinganoptimalactivityatmolecular
weights between 50 and 100 kDa [25]. Kanazawa et al. showed an increase in biocidal activity
ofpoly[tributyl(4-vinylbenzyl)phosphoniumchloride]againstS.aureuswithincreasingmolecular
weight[26]. Basedonthedescribedmechanism, theyassumethatahighermolecularweightand
aconsequentialhigherchargedensityenhancetheadsorptionofthepolymerstothecellmembrane.
Astrongeradsorptionleadstoastrongerdisruptionofthecellmembraneand,thus,toahigheractivity
ofthepolymer. However,Lienkampetal. foundthatwhenthemolecularweightreachesathreshold
value, theefficacyofthepolymersdecreases[27]. Additionally, Lococketal. reportedthereverse
effectonguanylatedpolymethacrylates[28]. Thepresentedpolymersshowedhigherantimicrobial
activity at lower molecular weights, proving that the efficacy of antimicrobial polymers does not
exclusivelydependontheirmolecularweight. Asecondfactorfortheantimicrobialbehavioristhe
alkylchainlengthofthehydrophobicmoiety. However,theoptimalalkylchainlengthisdifferentfor
differenttypesofpolymers. Pasquieretal. preparedbranchedpoly(ethyleneimine)swithpendant
ammoniumandalkylfunctionalities,rangingfromC toC . Anincreaseinthealkylchainlength
6 16
leadtoanincreaseintheantimicrobialactivityagainstE.coli[29]. Theactivitywasfurtherenhanced
by Heetal., attaching the hydrophobic chain directly to the ammonium group [30]. The opposite
influenceofaliphaticsidechainswasreportedbyXuetal.oncomb-likeionenes[31]. Here,adecrease
inthealkylchainlengthleadtoanincreaseintheantimicrobialactivityagainstE.coli. Ontheother
hand,Chenetal.preparedpoly(propyleneimine)dendrimerswithalkylchainsrangingfromC to
8
C ,showingaparabolicdependencebetweenthebiocidaleffectandthealkylchainlength,withthe
16
highestactivityatC [32].
10
In the current work, we present the preparation of various antimicrobial polymers based on
polyglycidolwithquaternarytrimethylammoniumgroupsasthecationicmoietyanddodecylchains
as the hydrophobic part. Polyglycidol is a highly functional polymer with a hydroxy group in
every repeating unit, allowing various further modifications [33,34]. It is non-toxic, soluble in
aqueous media, and licensed by the Food and Drug Administration (FDA) [35,36]. The cationic
andhydrophobicsidechainfunctionalitiesweredistributedstatisticallyalongthepolymerbackbone
(cationic–hydrophobicratioof1:1).Thisfunctionalizedpolyglycidolwascomparedto(i)apolyglycidol
modified with hydrophilic hydroxyethyl functionalities at the cationic center; (ii) a polyglycidol
with cationic and hydrophobic moieties at every repeating unit; and (iii) a polyglycidol with
a cationic–hydrophobic balance of 1:2. All polymers were tested in regard to their antimicrobial
propertiesagainstEscherichiacoliandStaphylococcusaureustoexamineapossiblerelationshipbetween
thestructureandthebiocidaleffectofthepolymer.
Polymers2018,10,96 3of19
2. MaterialsandMethods
2.1. Materials
Potassiumtert-butoxide(1MsolutioninTHF,SigmaAldrichChemieGmbH,Steinheim,Germany),
diglyme (≥99%, extra dry, over molecular sieves, Thermo Fisher Acros Organics, Geel, Belgium),
pyridine(99.5%,extradry,overmolecularsieves,ThermoFisherAcrosOrganics,Geel,Belgium),phenyl
chloroformate(>97%,SigmaAldrichChemieGmbH,Steinheim,Germany),4-nitrophenylchloroformate
(>98%, TCI Deutschland GmbH, Eschborn, Germany), 3-(dimethylamino)-1-propylamine (99%,
Thermo Fisher Acros Organics, Geel, Belgium), N-(3-aminopropyl)diethanolamine (>90%,
TCIDeutschlandGmbH,Eschborn,Germany),dodecylamine(98%,SigmaAldrichChemieGmbH,
Steinheim,Germany),4-dimethylaminopyridine(>98%,SigmaAldrichChemieGmbH,Steinheim,
Germany), DL-homocysteine thiolactone hydrochloride (98%, abcr GmbH, Karlsruhe, Germany),
triethylamine(≥99.5%, anhydrous, SigmaAldrichChemieGmbH,Steinheim, Germany), dodecyl
acrylate(>98%,TCIDeutschlandGmbH,Eschborn,Germany),methyliodide(>99%,SigmaAldrich
ChemieGmbH,Steinheim,Germany),tetrahydrofuran(99.8%,stabilizerfree,extradry,ThermoFisher
AcrosOrganics,Geel,Belgium),chloroform(99.9%,extradry,overmolecularsieves,ThermoFisher
AcrosOrganics,Geel,Belgium),N,N-dimethylformamide(99.8%,extradry,overmolecularsieves,
ThermoFisherAcrosOrganics,Geel,Belgium),methanol(≥99.8%,p.a.,Th. GeyerCHEMSOLUTE®,
Renningen, Germany), and dichloromethane (≥99.8%, anhydrous, Sigma Aldrich Chemie GmbH,
Steinheim,Germany)wereusedasreceived.
The3-phenyl-1-propanol(99%,SigmaAldrichChemieGmbH,Steinheim,Germany)wasstirred
withcalciumhydridefor24handthendistilled. Ethoxyethylglycidylether(EEGE)wassynthesized
from 2,3-epoxypropan-1-ol (glycidol, 96%, Sigma Aldrich Chemie GmbH, Steinheim, Germany)
and ethyl vinyl ether (99%, Sigma Aldrich Chemie GmbH, Steinheim, Germany) according to
Fittonetal.[37],purifiedbydistillation,andstoredunderanitrogenatmosphereoveramolecular
sieve(3Å).Polyglycidol(PG)(1)wassynthesizedaccordingtoliterature[38].
Water-sensitivereactionswerecarriedoutinanitrogenatmosphere. Nitrogen(Linde5.0)was
passedoveramolecularsieve(4Å)andfinelydistributedpotassiumonaluminumoxide.
2.2. Bacteria
To determine the antibacterial activity, polymers were tested against the Gram-negative
bacteriumEscherichiacoli(DSM498)andtheGram-positivebacteriumStaphylococcusaureus(ATCC6538).
Overnight cultures of E. coli and S. aureus with defined bacterial count in Mueller–Hinton broth
(SigmaAldrichChemieGmbH,Steinheim,Germany,pH=7.4±0.2)wereusedasinoculateinthe
antibacterialtest.
2.3. AntibacterialTestsofPolymerSolutions
Theantibacterialactivityofthepolymersinsolutionwasdeterminedbymeasuringtheminimal
inhibitory concentration (MIC) using the test bacteria mentioned above. Suspensions of strains
with known colony forming units (CFU; 1 × 106 -2 × 106 CFU·mL−1) were incubated at 37 ◦C in
nutrientsolutions(Mueller–HintonBroth,MHB)withdifferentconcentrationsofthepolymersamples.
Thepolymersamplesweresolubilizedinbidistilledwaterandaddedtothenutrientsolutionata
constantratioof1:10. Thegrowthofthebacteriawasfollowedduringtheincubationover20hby
measuringtheopticaldensityat612nmevery30min(with1400sofshakingat100rpmper30min
cyclebyusingamicroplatereader/incubator(TECANInfinite200Pro,TecanTradingAG,Männedorf,
Switzerland). The testing is performed with defined concentrations specifically for each polymer
until, within the monitoring time of 20 h, no bacterial growth curve is recorded. All experiments
were performed in triplicate duplicates and MIC determination was repeated on three different
days. Thepolymerswerenotsterilized. Sterilecontrols(definedpolymerconcentrationsinnutrient
solutionwithoutbacteria)wereassessedineverygrowthcurvemonitoringtestingseries. MICswere
Polymers2018,10,96 4of19
determinedaccordingtobrothmicrodilutionin96-wellmicrotitreplates[39]. Antimicrobialpolymer
testingreferencepolymers/controlsε-polylysineandpolyhexanide(poly(hexamethylenebiguanide))
wereused.
Theminimalinhibitoryconcentration(MIC)correspondstotheconcentrationofthetestsubstance
atwhichacompleteinhibitionofthegrowthoftheinoculatedbacteriawasobservedbycomparison
withcontrolsampleswithouttestsubstance.
2.4. HemolyticActivity
Hemolyticactivitywasassessedaccordingtoliterature[40]. Humanerythrocytes(fromhealthy
donors, red blood cells (RBC), 0, Rh positive, citrate-stabilized) were obtained by centrifugation
(3500rpm,12min)toremoveplasma,washedthreetimesinPBS(0.01Mphosphatebufferedsaline,
SigmaAldrichChemieGmbH,Steinheim,Germany),anddilutedinPBStoobtainastocksolutionof
2.5×108–3.0×108/mLRBC.Solutionsofdefinedpolymerconcentration(250µL)werepipettedinto
250µLofthestocksolution;thefinalamountofRBCbeing1.2×108–1.5×108RBC/mL.TheRBC
wereexposedfor60minat37◦Cunder3D-shaking;centrifugedthereafter(4000rpm,12min)and
theabsorptionofthesupernatant(diluted10-foldinPBS)wasdeterminedat414nminamicroplate
reader. Asreferencesolutions,(i)PBSfordeterminingspontaneoushemolysisand(ii)1%TritonX-100
for100%hemolysis(positivecontrol)wereused. Hemolysiswasplottedasafunctionofpolymer
concentrationandthehemolyticactivitywasdefinedasthepolymerconcentrationthatcauses50%
hemolysisofhumanRBCrelativetothepositivecontrol(HC ).
50
2.5. Measurements
1H NMR and 13C NMR were recorded on a Bruker DPX-400 FT-NMR spectrometer (Bruker
Corporation,Billerica,MA,USA)at400and101MHz,respectively. Deuteratedchloroform(CDCl ),
3
deuterateddimethylsulfoxide(DMSO-d ),deuteratedacetone(acetone-d ),anddeuteratedmethanol
6 6
(MeOD)wereusedassolvents. Theresidualsolventsignalwasusedasinternalstandard. Coupling
constantsJ aregiveninHz.
xy
Molecular weights (M ) and molecular weight distributions (Đ) were determined by size
n,SEC
exclusionchromatography(SEC).SECanalyseswerecarriedoutwithDMFaseluent. SECwithDMF
(HPLCgrade,VWR)aseluentwasperformedusinganAgilent1100system(AgilentTechnologies,
Santa Clara, CA, USA) equipped with a dual RI-/Visco detector (ETA-2020, WGE Dr. Bures
GmbH & Co KG, Dallgow-Doeberitz, Germany). The eluent contained 1 g·L−1 LiBr (≥99%,
Sigma Aldrich Chemie GmbH, Steinheim, Germany). The sample solvent contained traces of
distilled water as internal standard. For cationic samples, the eluent contained 2 g·L−1 LiBr and
2g·L−1tris(hydroxymethyl)aminomethane(TRIS,ultrapuregrade,≥99.9%,SigmaAldrichChemie
GmbH, Steinheim, Germany). One pre-column (8 mm × 50 mm) and four GRAM gel columns
(8mm×300mm, Polymer Standards Service, Mainz, Germany) were applied at a flow rate of
1.0mL·min−1at40◦C.Thediameterofthegelparticlesmeasured10µm,thenominalporewidths
were30, 100, 1000, and3000Å.Calibrationwasachievedusingnarrowlydistributedpoly(methyl
methacrylate) standards (Polymer Standards Service, Mainz, Germany). Results were evaluated
usingthePSSWinGPCUniChromsoftware(Version8.1.1, PSSPolymerStandardsServiceGmbH,
Mainz,Germany).
DialysiswasperformedinmethanolusingBiotechCETubing(MWCO:100–500D,3.1mL·cm−1,
SpectrumLaboratories,Inc.,RanchoDominguez,CA,USA)andBiotechRCTubing(MWCO:1kD,
6.4mL·cm−1,SpectrumLaboratories,Inc.,RanchoDominguez,CA,USA),respectively.Themembrane
waswashedfor15mininwaterbeforeusetoremovethesodiumazidesolution.
2.6. SynthesisofPoly(glycidylphenylcarbonate)(P(GPC) )(2)
27
PG (1) (2.018 g, 27.24 mmol OH) was dissolved in pyridine (18.87 mL), and a solution of
27
phenyl chloroformate (4.692 g, 29.97 mmol) in dichloromethane (17.5 mL) was added in 30 min
Polymers2018,10,96 5of19
at 0 ◦C using a syringe pump. The reaction mixture was allowed to warm to room temperature
and stirred for 20 h. The precipitate was removed by filtration. The solution was washed with
water (15 mL), 1 M HCl solution (aq.) (3 × 15 mL), and saturated NaCl solution (aq.) (15 mL).
The organic phase was dried over Na SO , filtrated, and the solvent removed under reduced
2 4
pressure. Polymer2wasobtainedasabrownviscousliquid(3.650g,69%). M =5243g·mol−1,
n,NMR
M = 4800 g·mol−1, Ð = 1.14. 1H NMR (400 MHz, CDCl ) (2): δ = 1.79 (m, ArCH CH ),
n,SEC 3 2 2
2.57 (t, 3J = 7.8 Hz, ArCH CH ), 3.45–3.87 (m, ArCH CH CH , OCH CH(CH OC=OOPh)O),
HH 2 2 2 2 2 2 2
4.08–4.42(m,OCH CH(CH OC=OOPh)O),6.98–7.29(m,ArCH CH ,(OC=OOPh)O)ppm. 13CNMR
2 2 2 2
(101 MHz, CDCl ) (2): δ = 31.2 (ArCH CH ), 32.3 (ArCH CH ), 67.7–69.4 (ArCH CH CH ,
3 2 2 2 2 2 2 2
OCH CH(CH OC=OOPh)O),77.4(OCH CH(CH OC=OOPh)O),121.0(OC=OOPh)O),126.1(ArCH ,
2 2 2 2 2
OC=OOPh)O),128.4(ArCH ),128.5(ArCH ),129.6(OC=OOPh)O),141.8(ArCH ),151.1(OC=OOPh)O),
2 2 2
153.6(OC=OOPh)O)ppm.
2.7. SynthesisofPoly(glycidyl3-dimethylaminopropylcarbamate-co-glycidyldodecylcarbamate)
(P(GDMAPA -co-GDDA ))(3)
15 12
P(GPC) (2) (1.509 g, 7.77 mmol carbonate) was dissolved in tetrahydrofuran (15 mL)
27
and a solution of 3-(dimethylamino)-1-propylamine (0.397 g, 3.89 mmol) and dodecylamine
(0.721 g, 3.89 mmol) in tetrahydrofuran (15 mL) was added in 1 h at 0 ◦C using a
syringe pump. The reaction was allowed to warm to room temperature and stirred for
42 h. The solvent was removed under reduced pressure and the polymer purified by
dialysis in methanol. Polymer 3 was obtained as a yellowish viscous liquid (1.153 g, 62%).
M = 6459 g·mol−1, M = 7600 g·mol−1, Ð = 1.38. 1H NMR (400 MHz, CDCl )
n,NMR n,SEC 3
(3): δ = 0.84 (t, 3J = 7.0 Hz, NHCH CH (CH ) CH ), 1.21 (s, NHCH CH (CH ) CH ),
HH 2 2 2 9 3 2 2 2 9 3
1.34–1.51 (m, NHCH CH (CH ) CH ), 1.54–1.68 (m, NHCH CH CH N(CH ) ), 1.77–1.89 (m,
2 2 2 9 3 2 2 2 3 2
ArCH CH ), 2.16 (s, NHCH CH CH N(CH ) ), 2.27 (t, 3J = 6.7 Hz, NHCH CH CH N(CH ) ),
2 2 2 2 2 3 2 HH 2 2 2 3 2
2.63 (t, 3J = 7.6 Hz, ArCH CH ), 3.01–3.11 (m, NHCH CH (CH ) CH ), 3.12–3.21 (m, 2H,
HH 2 2 2 2 2 9 3
NHCH CH CH N(CH ) ), 3.45–3.79 (m, ArCH CH CH , OCH CH(CH OC=ONHR)O), 3.86–4.36
2 2 2 3 2 2 2 2 2 2
(m,OCH CH(CH OC=ONHR)O),5.88(br. s,NH),6.17(br. s,NH),7.09–7.25(m,ArCH CH )ppm.
2 2 2 2
13CNMR(101MHz,CDCl )(3): δ=14.2(NHCH CH (CH ) CH ),22.7(NHCH (CH ) CH ),27.0
3 2 2 2 9 3 2 2 10 3
(NHCH CH CH N(CH ) ,27.5–32.0(NHCH (CH ) CH ,ArCH CH ),39.9(NHCH (CH ) CH ),
2 2 2 3 2 2 2 10 3 2 2 2 2 10 3
41.2 (NHCH CH CH N(CH ) ), 45.5 (NHCH CH CH N(CH ) ), 57.6 (NHCH CH CH N(CH ) ),
2 2 2 3 2 2 2 2 3 2 2 2 2 3 2
64.2–70.0(ArCH CH CH ,OCH CH(CH OC=ONHR)O),78.0(OCH CH(CH OC=ONHR)O),125.8
2 2 2 2 2 2 2
(ArCH ),128.4(ArCH ),128.5(ArCH ),141.9(ArCH ),156.7(OCH CH(CH OC=ONHR)O)ppm.
2 2 2 2 2 2
2.8. SynthesisofPoly(glycidyl3-aminopropyldiethanolcarbamate-co-glycidyldodecylcarbamate)
(P(GAPDEA -co-GDDA ))(4)
16 11
P(GPC) (2)(0.707g,3.51mmolcarbonate)wasdissolvedintetrahydrofuran(10mL)andasolution
27
ofN-(3-aminopropyl)diethanolamine(0.284g,1.75mmol),anddodecylamine(0.325g,1.75mmol)in
tetrahydrofuran(5mL)wasaddedin1hat0◦Cusingasyringepump.Thereactionwasallowedto
warmtoroomtemperatureandstirredfor42h. Thesolventwasremovedunderreducedpressure
and the polymer purified by dialysis in methanol. Polymer 4 was obtained as a colorless viscous
liquid(0.655g,66%).M =7337g·mol−1,M =14,100g·mol−1,Ð=3.56. 1HNMR(400MHz,
n,NMR n,SEC
MeOD) (4): δ = 0.92 (t, 3J = 7.0 Hz, NHCH CH (CH ) CH ), 1.31 (s, NHCH CH (CH ) CH ),
HH 2 2 2 9 3 2 2 2 9 3
1.44–1.59(m,NHCH CH (CH ) CH ),1.62–1.76(m,NHCH CH CH N(CH CH OH) ),1.85–1.92(m,
2 2 2 9 3 2 2 2 2 2 2
ArCH CH ), 2.55–2.74 (m, CH N(CH CH OH) ), 3.06–3.14 (m, NHCH CH (CH ) CH ), 3.15–3.23
2 2 2 2 2 2 2 2 2 9 3
(m, NHCH CH CH N(CH CH OH) ), 3.62 (t, 3J = 5.4 Hz, CH N(CH CH OH) ), 3.66–3.81 (m,
2 2 2 2 2 2 HH 2 2 2 2
ArCH CH CH ,OCH CH(CH OC=ONHR)O),4.00–4.34(m,OCH CH(CH OC=ONHR)O),7.17–7.32
2 2 2 2 2 2 2
(m,ArCH CH )ppm. 13CNMR(101MHz,MeOD)(4): δ=14.6(NHCH CH (CH ) CH ),23.8–30.9
2 2 2 2 2 9 3
(NHCH CH (CH ) CH ),28.2(NHCH CH CH N(CH CH OH) ),33.1(NHCH CH (CH ) CH ),40.1
2 2 2 9 3 2 2 2 2 2 2 2 2 2 9 3
(NHCH CH CH N(CH CH OH) ), 42.0 (NHCH CH (CH ) CH ), 53.6 (CH N(CH CH OH) ),
2 2 2 2 2 2 2 2 2 9 3 2 2 2 2
Polymers2018,10,96 6of19
57.6 (CH N(CH CH OH) ), 60.8 (CH N(CH CH OH) ), 65.3–79.3 (ArCH CH CH ,
2 2 2 2 2 2 2 2 2 2 2
OCH CH(CH OC=ONHR)O),129.4(ArCH ),129.6(ArCH ),158.7(OCH CH(CH OC=ONHR)O)ppm.
2 2 2 2 2 2
2.9. SynthesisofPoly(glycidyl3-trimethylaminopropylcarbamate-co-glycidyldodecylcarbamate)
(P(GTMAPA -co-GDDA ))(5)
15 12
P(GDMAPA -co-GDDA ) (3) (0.147 g, 0.34 mmol –NMe ) was dissolved in THF (3.0 mL).
15 12 2
Methyl iodide (0.058 g, 0.41 mmol) was added and the solution was stirred for 20 h at
room temperature. Excess methyl iodide and the solvent were removed under reduced
pressure and the polymer purified by dialysis in methanol. Polymer 5 was obtained as a
yellowish crystalline solid (0.205 g, 89%). M = 10,111 g·mol−1, M = 4400 g·mol−1,
n,NMR n,SEC
Ð = 1.18. 1H NMR (400 MHz, DMSO-d ) (5): δ = 0.74–0.90 (m, NHCH CH (CH ) CH ),
6 2 2 2 9 3
1.20 (s, NHCH CH (CH ) CH ), 1.30–1.44 (m, NHCH CH (CH ) CH ), 1.72–1.91 (m,
2 2 2 9 3 2 2 2 9 3
NHCH CH CH N+(CH ) , ArCH CH ), 2.55–2.62 (m, 3J = 7.6 Hz, ArCH CH ), 2.85–2.99
2 2 2 3 3 2 2 HH 2 2
(m,NHCH CH (CH ) CH ),3.00–3.17(m,NHCH CH CH N+(CH ) ,NHCH CH CH N+(CH ) ),
2 2 2 9 3 2 2 2 3 3 2 2 2 3 3
3.26–3.43(m,NHCH CH CH N+(CH ) ),3.44–3.74(m,ArCH CH CH ,OCH CH(CH OC=ONHR)O),
2 2 2 3 3 2 2 2 2 2
3.82–4.19 (m, OCH CH(CH OC=ONHR)O), 7.10–7.30 (m, ArCH CH ) ppm. 13C NMR (101
2 2 2 2
MHz, DMSO-d ) (5): δ = 13.8 (NHCH CH (CH ) CH ), 22.0–28.9 (NHCH (CH ) CH ), 26.2
6 2 2 2 9 3 2 2 10 3
(NHCH CH CH N+(CH ) ), 31.2 (NHCH (CH ) CH ), 37.3 (NHCH CH CH N+(CH ) ),
2 2 2 3 3 2 2 10 3 2 2 2 3 3
52.2 (NHCH CH CH N+(CH ) ), 63.2 (NHCH CH CH N+(CH ) ), 68.6–77.0 (ArCH CH CH ,
2 2 2 3 3 2 2 2 3 3 2 2 2
OCH CH(CH OC=ONHR)O), OCH CH(CH OC=ONHR)O), 125.5 (ArCH ), 128.9 (ArCH ), 141.5
2 2 2 2 2 2
(ArCH ),156.0(OCH CH(CH OC=ONHR)O)ppm.
2 2 2
2.10. SynthesisofPoly(glycidyl3-aminopropyldiethanolmethylcarbamate-co-glycidyldodecylcarbamate)
(P(GAPDEMA -co-GDDA ))(6)
16 11
P(GAPDEA -co-GDDA ) (4) (0.216 g, 0.47 mmol –NEtOH ) was dissolved in THF (2.5 mL).
16 11 2
Methyl iodide (0.081 g, 0.57 mmol) was added and the solution was stirred for 20 h at
room temperature. Excess methyl iodide and the solvent were removed under reduced
pressure and the polymer purified by dialysis in methanol. Polymer 6 was obtained as a
slightly yellow solid (0.238 g, 84%). M = 9608 g·mol−1, M = not measurable.
n,NMR n,SEC
1H NMR (400 MHz, MeOD) (6): δ = 0.96 (t, 3J = 6.3 Hz, NHCH CH (CH ) CH ),
HH 2 2 2 9 3
1.35 (s, NHCH CH (CH ) CH ), 1.48–1.65 (m, NHCH CH (CH ) CH ), 1.88–1.99 (m,
2 2 2 9 3 2 2 2 9 3
ArCH CH ), 2.05–2.23 (m, NHCH CH CH N+(CH (CH CH OH) )), 2.70–2.78 (m, ArCH CH ),
2 2 2 2 2 3 2 2 2 2 2
3.09–3.20 (m, NHCH CH (CH ) CH ), 3.24–3.42 (m, NHCH CH CH N+(CH (CH CH OH) )),
2 2 2 9 3 2 2 2 3 2 2 2
3.51–3.96 (m, ArCH CH CH , OCH CH(CH OC=ONHR)O, CH N+(CH (CH CH OH) )),
2 2 2 2 2 2 3 2 2 2
4.02–4.42 (m, OCH CH(CH OC=ONHR)O, CH N+(CH (CH CH OH) )), 7.20–7.36 (m,
2 2 2 3 2 2 2
ArCH CH ) ppm. 13C NMR (101 MHz, MeOD) (6): δ = 14.5 (NHCH CH (CH ) CH ),
2 2 2 2 2 9 3
23.7–31.0 (NHCH CH (CH ) CH ), 28.0 (NHCH CH CH N+(CH (CH CH OH) ), 33.0
2 2 2 9 3 2 2 2 3 2 2 2
(NHCH CH (CH ) CH ),38.9(NHCH CH CH N+(CH (CH CH OH) )),42.0(NHCH CH (CH ) CH ),
2 2 2 9 3 2 2 2 3 2 2 2 2 2 2 9 3
50.9(NHCH CH CH N+(CH (CH CH OH) ),56.8(NHCH CH CH N+(CH (CH CH OH) ),62.8–79.1
2 2 2 3 2 2 2 2 2 2 3 2 2 2
(ArCH CH CH ,OCH CH(CH OC=ONHR)O),65.4(CH N+(CH (CH CH OH) ),129.4(ArCH ),129.6
2 2 2 2 2 2 3 2 2 2 2
(ArCH ),158.7(OCH CH(CH OC=ONHR)O)ppm.
2 2 2
2.11. SynthesisofPoly(glycidyl-4-nitrophenylcarbonate)(P(GNPC) )(7)
27
PG (1) (2.012 g, 27.16 mmol OH) was dissolved in pyridine (18.85 mL). The 4-nitrophenyl
27
chloroformate (6.023 g, 29.88 mmol) was dissolved in dichloromethane (20 mL) and added to the
polymer solution via syringe pump in 30 min at 0 ◦C. The solution was stirred for 20 h at room
temperature. The crude product was washed with water (30 mL), 1 M HCl (aq.) (3 × 30 mL),
and saturated NaCl solution (aq.) (30 mL). The organic phase was separated, dried over Na SO
2 4
and precipitated in cold MeOH. The solvent was removed under reduced pressure and polymer
7 was obtained as a colorless solid (5.782 g, 89%). M = 6458 g·mol−1, M = 6600 g·mol−1,
n,NMR n,SEC
Polymers2018,10,96 7of19
Ð=1.41. 1HNMR(400MHz,DMSO-d )(7): δ=1.69–1.83(m,ArCH CH ),2.54–2.61(m,ArCH CH ),
6 2 2 2 2
3.54–3.95(m,ArCH CH CH ,OCH CH(CH OC=OOArNO )O),4.15–4.56(d,CH OC=OOArNO ),
2 2 2 2 2 2 2 2
7.08–7.25(m,ArCH CH ),7.42(s,CH OC=OOArNO ),8.18(s,CH OC=OOArNO )ppm. 13CNMR
2 2 2 2 2 2
(101MHz,DMSO-d )(7): δ=30.8(ArCH CH ),31.6(ArCH ),68.2(OCH CH(CH OC=OOArNO )O),
6 2 2 2 2 2 2
76.4(OCH CH(CH OC=OOArNO )O),76.5(ArCH CH CH ),76.6(OCH CH(CH OC=OOArNO )O),
2 2 2 2 2 2 2 2 2
122.3(CH OC=OOArNO ),125.2(CH OC=OOArNO ),125.7(ArCH ),128.2(ArCH ),128.3(ArCH ),
2 2 2 2 2 2 2
141.6(ArCH ),145.0(CH OC=OOArNO ),152.0(OC=OO),155.1(CH OC=OOArNO )ppm.
2 2 2 2 2
2.12. SynthesisofPoly(glycidylhomocysteinethiolactonylcarbamate)(P(GHCTL) )(8)
27
P(GNPC) (7) (1.020 g, 4.26 mmol carbonate) was dissolved in DMF (10 mL), and
27
4-(dimethylamino)pyridine (0.053 g, 0.43 mmol) and DL-homocysteine thiolactone hydrochloride
(0.655 g, 4.26 mmol) were added. The mixture was cooled to 0 ◦C and triethylamine (0.862 g,
8.52 mmol) was added over 1 h via syringe pump. The solution was stirred for 20 h at room
temperature. DMF was removed under reduced pressure at 50 ◦C and the crude product was
precipitated in MeOH. Drying under reduced pressure at 50 ◦C gave polymer 8 as a slightly
yellow solid (0.694 g, 75%). M = 5865 g·mol−1, M = 6900 g·mol−1, Ð = 1.44. 1H NMR
n,NMR n,SEC
(400 MHz, DMSO-d ) (8): δ = 1.74–1.83 (m, ArCH CH ), 2.00–2.48 (m, C=OSCH CH CHR), 2.60
6 2 2 2 2
(t, 3J = 7.5 Hz, ArCH CH ), 3.17–3.45 (m, C=OSCH CH CHR), 3.47–3.75 (m, ArCH CH CH ,
H,H 2 2 2 2 2 2 2
OCH CH(CH OC=ONHR)O), 3.86–4.23 (m, CH OC=ONHR), 4.26–4.42 (m, C=OSCH CH CHR),
2 2 2 2 2
7.14–7.29(Ar),7.55(brs,NH)ppm. 13CNMR(101MHz,DMSO-d )(8): δ=26.5(C=OSCH CH CHR),
6 2 2
29.8 (C=OSCH CH CHR), 30.9 (ArCH CH ), 31.6 (ArCH ), 59.9 (CH OC=ONHR), 63.7, 68.7, 77.2
2 2 2 2 2 2
(ArCH CH CH , OCH CH(CH OC=ONHR)O), 79.2 (C=OSCH CH CHR), 128.3 (ArCH ), 128.4
2 2 2 2 2 2 2 2
(ArCH ),156.0(OC=ONHR),205.7(C=OSCH CH CHR)ppm.
2 2 2
2.13. SynthesisofP(GDDAc) (9)
27
To a mixture of P(GHCTL) (8) (0.301 g, 1.386 mmol HCTL) and dodecyl acrylate (0.833 g,
27
3.464 mmol) in chloroform (3.0 mL), 3-(dimethylamino)-1-propylamine (0.353 g, 3.464 mmol) was
addedin30minviasyringepumpatroomtemperature. Themixturewasstirredfor20hatroom
temperature. Chloroform was removed under reduced pressure. Dialysis in acetone gave 9 as
a colorless, viscous liquid (0.628 g, 81%). M = 15,115 g·mol−1, M = 15,300 g·mol−1,
n,NMR n,SEC
Ð = 1.36. 1H NMR (400 MHz, CDCl ) (9): δ = 0.82 (t, 3J = 6.8 Hz, CH CH (CH ) CH ),
3 H,H 2 2 2 9 3
1.20 (s, CH CH (CH ) CH ), 1.48–1.69 (m, CH CH N(CH ) , CH CH (CH ) CH , ArCH CH ),
2 2 2 9 3 2 2 3 2 2 2 2 9 3 2 2
1.76–2.08 (m, CHCH CH SCH ), 2.15 (s, CH N(CH ) ), 2.22–2.37 (m, CH N(CH ) ), 2.43–2.61 (m,
2 2 2 2 3 2 2 3 2
CHCH CH SCH CH ),2.64–2.78(m,CHCH CH SCH CH ),3.07–3.37(m,NHCH CH CH N(CH ) ),
2 2 2 2 2 2 2 2 2 2 2 3 2
3.41–3.75 (m, ArCH CH CH , OCH CH(CH OC=ONHR)O), 3.77–4.07 (m, CH OC=ONHCH),
2 2 2 2 2 2
4.10–4.41 (m, O=COCH CH ), 7.09–7.23 (m, Ar), 7.76 (br. s, NH) ppm. 13C NMR (101 MHz,
2 2
CDCl ) (9): δ = 14.1 (CH CH (CH ) CH ), 22.7–31.9 (CH CH (CH ) CH , CHCH CH SCH ,
3 2 2 2 9 3 2 2 2 9 3 2 2 2
ArCH CH ),26.8(CHCH CH SCH CH ),28.2(CH CH N(CH ) ),28.6(CHCH CH SCH CH ),34.7
2 2 2 2 2 2 2 2 3 2 2 2 2 2
(CHCH CH SCH CH ), 38.7 (NHCH CH CH N(CH ) ), 45.5 (CH N(CH ) ), 54.1 (NHCH), 57.9
2 2 2 2 2 2 2 3 2 2 3 2
(CH N(CH ) ),64.9(O=COCH CH ),125.9(ArCH ),128.3(ArCH ),128.5(ArCH ),140.0(ArCH ),
2 3 2 2 2 2 2 2 2
156.4(OC=ONH),171.5(CHC=ONH),172.0(CH C=OO)ppm.
2
2.14. SynthesisofP(GDDAc,q) (10)
27
P(GDDAc) (9)(0.431g,0.770mmol–NMe )wasdissolvedinTHF(9.0mL),andmethyliodide
27 2
(0.131g,0.923mmol)wasadded. Thesolutionwasstirredatroomtemperaturefor20h. Removalof
THFandexcessmethyliodideunderreducedpressureanddialysisinmethanolgavepolymer10as
aslightlyyellowsolid(0.475g,88%). M =18,947g·mol−1,M =11,800g·mol−1,Ð=1.36.
n,NMR n,SEC
1H NMR (400 MHz, CDCl ) (10): δ = 0.81 (t, 3J = 6.5 Hz, CH CH (CH ) CH ), 1.05–1.32 (m,
3 H,H 2 2 2 9 3
CH CH (CH ) CH ),1.46–1.62(m,CH CH (CH ) CH ),1.85–2.25(m,CH CH N+(CH ) ,ArCH CH ,
2 2 2 9 3 2 2 2 9 3 2 2 3 3 2 2
Polymers2018,10,96 8of19
CHCH CH SCH ), 2.39–2.64 (m, CHCH CH SCH CH ), 2.66–2.82 (m, CHCH CH SCH CH ),
2 2 2 2 2 2 2 2 2 2 2
3.05–3.50(m,NHCH CH CH N+(CH ) ),3.51–3.83(m,ArCH CH CH ,OCH CH(CH OC=ONHR)O),
2 2 2 3 3 2 2 2 2 2
3.84–4.50(m,CH OC=ONHCH,O=COCH CH ),7.08–7.24(m,Ar),7.77(br.s,NH)ppm.13CNMR(101
2 2 2
MHz,CDCl )(10): δ=14.1(CH CH (CH ) CH ),22.6–31.9(CH CH (CH ) CH ,CHCH CH SCH ,
3 2 2 2 9 3 2 2 2 9 3 2 2 2
ArCH CH ), 26.7 (CHCH CH SCH CH ), 28.3 (CH CH N+(CH ) ), 28.6 (CHCH CH SCH CH ),
2 2 2 2 2 2 2 2 3 3 2 2 2 2
34.8 (CHCH CH SCH CH ), 40.1 (NHCH CH CH N+(CH ) ), 53.8 (CH N+(CH ) , NHCH), 64.9
2 2 2 2 2 2 2 3 3 2 3 3
(CH N+(CH ) ,O=COCH CH ),156.5(OC=ONH),172.1(CHC=ONH),172.8(CH C=OO)ppm.
2 3 3 2 2 2
2.15. SynthesisofP(GDMAPA -co-GDDADDAc )(11)
14 13
P(GNPC) (7) (0.541 g, 2.26 mmol carbonate) was dissolved in DMF (11 mL) and
27
3-(dimethylamino)-1-propylamine (0.115 g, 1.13 mmol) was added in 30 min via syringe pump.
Themixturewasstirredfor20hatroomtemperature. DL-homocysteinethiolactonehydrochloride
(0.174g,1.13mmol)and4-(dimethylamino)pyridine(0.013g,0.11mmol)wereadded. Themixture
wascooledto0 ◦C,andtriethylamine(0.229g, 2.26mmol)wasaddedover1hviasyringepump.
Thesolutionwasstirredfor20hatroomtemperature. DMFwasremovedunderreducedpressure
atroomtemperature. Thecrudeproductwasdissolvedinchloroform,anddodecylacrylate(0.680g,
2.83mmol)wasadded. Themixturewascooledto0◦C,anddodecylamine(0.525g,2.83mmol)was
addedin30minusingasyringepump. Afterstirringfor20hatroomtemperature,thesolventwas
removedandthecrudeproductwaspurifiedbydialysisinacetone. Polymer11wasreceivedasa
slightlyyellow, viscousliquid(0.469g, 48%). M =11,631g·mol−1, M =10,800g· mol−1,
n,NMR n,SEC
Ð = 1.36. 1H NMR (400 MHz, CDCl /acetone-d (6:4)) (11): δ = 0.81 (t, 3J = 6.6 Hz
3 6 H,H
CH CH (CH ) CH ),1.20(s,CH CH (CH ) CH ),1.38–1.50(m,NHCH CH (CH ) CH ),1.51–1.64
2 2 2 9 3 2 2 2 9 3 2 2 2 9 3
(m, OCH CH (CH ) CH ), 1.70–1.86 (m, CH CH N(CH ) ), 1.88–2.01 (m, CHCH CH SCH ),
2 2 2 9 3 2 2 3 2 2 2 2
2.29–2.77 (m, CH N(CH ) , CHCH CH SCH CH ), 2.97–3.30 (m, NHCH CH CH N(CH ) ,
2 3 2 2 2 2 2 2 2 2 3 2
NHCH CH (CH ) CH ), 3.44–3.79 (m, ArCH CH CH , OCH CH(CH OC=ONHR)O), 3.90–4.34
2 2 2 9 3 2 2 2 2 2
(m, CH OC=ONHR, CH OC=ONHCH, O=COCH CH ), 7.07–7.24 (m, Ar) ppm. 13C
2 2 2 2
NMR (101 MHz, CDCl /acetone-d (6:4)) (11): δ = 13.5 (CH CH (CH ) CH ), 22.1–31.4
3 6 2 2 2 9 3
(CH CH (CH ) CH ,CHCH CH SCH ,ArCH CH ,CH CH N(CH ) ),34.2(CHCH CH SCH CH ),
2 2 2 9 3 2 2 2 2 2 2 2 3 2 2 2 2 2
38.4 (NHCH CH CH N(CH ) ), 39.0 (NHCH CH (CH ) CH ), 43.7 (CH N(CH ) ), 53.3 (NHCH),
2 2 2 3 2 2 2 2 9 3 2 3 2
56.0 (CH N(CH ) ), 64.2 (O=COCH CH ), 127.8 (ArCH ), 127.9 (ArCH ), 155.9 (OC=ONH), 156.2
2 3 2 2 2 2 2
(OC=ONH),171.4(CHC=ONH),172.1(CH C=OO)ppm.
2
2.16. SynthesisofP(GTMAPA -co-GDDADDAc )(12)
14 13
P(GDMAPA -co-GDDADDAc )(11)(0.179g,0.20mmol–NMe )wasdissolvedinTHF(2.0mL),and
14 13 2
methyliodide(0.036g,0.25mmol)wasadded. Thesolutionwasstirredatroomtemperaturefor20
h. RemovalofTHFandexcessmethyliodideunderreducedpressureanddialysisinmethanolgave
polymer12asaslightlyyellowsolid(0.203g,quant.).M =13,476g·mol−1,M =9400g·mol−1,
n,NMR n,SEC
Ð = 1.41. 1H-NMR (400 MHz, CDCl /acetone-d (6:4)) (12): δ = 0.80 (t, 3J = 6.8 Hz
3 6 H,H
CH CH (CH ) CH ),1.18(s,CH CH (CH ) CH ),1.36–1.48(m,NHCH CH (CH ) CH ),1.50–1.66
2 2 2 9 3 2 2 2 9 3 2 2 2 9 3
(m, OCH CH (CH ) CH ), 1.74–2.01 (m, CH CH N+(CH ) , CHCH CH SCH ), 2.42–2.89
2 2 2 9 3 2 2 3 3 2 2 2
(m, CHCH CH SCH CH ), 2.94–3.45 (m, NHCH CH CH N+(CH ) , NHCH CH (CH ) CH ),
2 2 2 2 2 2 2 3 3 2 2 2 9 3
3.49–3.81 (m, ArCH CH CH , OCH CH(CH OC=ONHR)O), 3.87–4.38 (m, CH OC=ONHR,
2 2 2 2 2 2
CH OC=ONHCH,O=COCH CH ),7.03–7.23(m,Ar)ppm. 13CNMR(101MHz,CDCl /acetone-d
2 2 2 3 6
(6:4)) (12): δ = 13.4 (CH CH (CH ) CH ), 22.1–31.3 (CH CH (CH ) CH , CHCH CH SCH ,
2 2 2 9 3 2 2 2 9 3 2 2 2
ArCH CH , CH CH N(CH ) ), 34.2 (CHCH CH SCH CH ), 38.9 (NHCH CH (CH ) CH ), 43.0
2 2 2 2 3 2 2 2 2 2 2 2 2 9 3
(NHCH CH CH N+(CH ) ),53.0(CH N+(CH ) ),53.8(NHCH),64.1(CH N(CH ) ,2O=COCH CH ),
2 2 2 3 2 2 3 3 2 3 2 2 2
127.8(ArCH ),127.9(ArCH ),141.3(ArCH ),155.9(OC=ONH),156.4(OC=ONH),171.3(CHC=ONH),
2 2 2
171.4(CH C=OO)ppm.
2
Polymers2018,10,96 9of19
3. ResultsandDiscussion
In the current work, we present the synthesis and characterization of various novel
cationic–hydrophobicfunctionalizedpolyglycidols. Thefunctionalpolyethersareevaluatedinregard
totheirantibacterialactivityagainstE.coliandS.aureus,inducedbydifferentmicrostructures.
Thereto, a polyglycidol with statistically distributed cationic and hydrophobic groups
(cationic–hydrophobicratioof1:1)wascomparedto(a)apolyglycidolwithahydrophilicmodification
at the cationic moieties; (b) a polyglycidol with cationic and hydrophobic functionalities at every
repeatingunit;and(c)apolyglycidolwithacationic–hydrophobicbalanceof1:2(Figure1).
Linear polyglycidol was synthesized by anionic ring-opening polymerization of ethoxyethyl
glycidyl ether with 3-phenyl-1-propanol as initiator, followed by removal of the acetal protecting
groups under acidic conditions [38]. Polyglycidol with 27 repeating units (PG (1)) and
Polymers 2018, 10, 96 27 9 of 18
M = 2900 g· mol−1 was obtained with a narrow molecular weight distribution (Ð = 1.13).
n,SEC
T29h0e01 gH·m,1o3Cl−1 NwMasR osbptaeicnterad awnidthS aE Cnaarnroawly smisoolefcPuGla2r7 w(1e)icgahnt dbiestfroiubnudtioinn (thÐe =s u1.p1p3)o. rTtihneg 1iHn,f o13rCm NatMioRn
(sFpiegcutrreas aSn1d– SS3E)C. analysis of PG27 (1) can be found in the supporting information (Figures S1–S3).

FFiigguurree 11.. CCoommppaarriissoonn ooff vvaarriioouuss ccaattiioonniicc––hhyyddrroopphhoobbiicc ffuunnccttiioonnaalliizzeedd ppoollyyggllyycciiddoollss iinn rreeggaarrdd ttoo tthheeiirr
aannttiibbaacctteerriiaall aaccttiivviittyy aaggaaiinnsstt EE.. ccoollii aanndd SS.. aauurreeuuss ttoo eexxaammiinnee tthhee ssttrruuccttuurree––pprrooppeerrttyyr reellaattiioonnsshhiipp..
33..11.. SSyynntthheessiiss ooff PP((GGTTMMAAPPAA15-c-oc-oG-GDDDAD12A) (5)) (a5n)da nPd(GPA(PGDEAMPAD1E6-McoA-G-DcDoA-1G1)D (D6)A )(6)
15 12 16 11
The general approach for the functionalization of linear polyglycidol with cationic and
The general approach for the functionalization of linear polyglycidol with cationic and
hydrophobic groups starts with the introduction of active ester functionalities to the polymer
hydrophobicgroupsstartswiththeintroductionofactiveesterfunctionalitiestothepolymerbackbone.
backbone. The active esters allow the reaction with primary amines under the selective formation of
Theactiveestersallowthereactionwithprimaryaminesundertheselectiveformationofcarbamate
carbamate moieties. Quaternization of introduced tertiary amines gave the cationic component.
moieties. Quaternizationofintroducedtertiaryaminesgavethecationiccomponent.
PG27 (1) was reacted with phenyl chloroformate in pyridine/dichloromethane at room temperature
(Scheme 1a). For purification, poly(glycidyl phenyl carbonate)27 (2) was washed with water, 1 M HCl
solution (aq.), and saturated NaCl solution (aq.) to remove pyridine hydrochloride and excess pyridine.
The successful functionalization was confirmed by 1H NMR, 13C NMR spectroscopy, and SEC analysis
(Figures S4–S6). The introduced phenyl carbonate groups are excellent electrophiles for the substitution
reaction with non-functionalized, primary amines. P(GPC)27 (2) was subsequently reacted with
dodecylamine (DDA) and 3-(dimethylamino)-1-propylamine (DMAPA) or N-(3-
aminopropyl)diethanolamine (APDEA) in THF at room temperature in a 1:1 ratio (Scheme 1b). The
prepared poly(glycidyl 3-dimethylaminopropylcarbamate-co-glycidyl dodecylcarbamate) (P(GDMAPA15-co-
GDDA12)) (3) and poly(glycidyl 3-aminopropyldiethanolcarbamate-co-glycidyl dodecylcarbamate)
(P(GAPDEA16-co-GDDA11)) (4) were purified by dialysis in methanol and characterized by 1H NMR, 13C NMR
spectroscopy, and SEC analysis (Figures S7–S12). In both cases, the different functional groups are
statistically distributed along the polyglycidol backbone. However, the higher reactivity of DMAPA and
APDEA in comparison to DDA leads to a slightly uneven ratio of functionalities. P(GDMAPA15-co-GDDA12) (3)
Polymers2018,10,96 10of19
PG (1) was reacted with phenyl chloroformate in pyridine/dichloromethane at room
27
temperature(Scheme1a). Forpurification,poly(glycidylphenylcarbonate) (2)waswashedwith
27
water,1MHClsolution(aq.),andsaturatedNaClsolution(aq.) toremovepyridinehydrochloride
and excess pyridine. The successful functionalization was confirmed by 1H NMR, 13C NMR
spectroscopy,andSECanalysis(FiguresS4–S6). Theintroducedphenylcarbonategroupsareexcellent
electrophilesforthesubstitutionreactionwithnon-functionalized,primaryamines. P(GPC) (2)was
27
subsequentlyreactedwithdodecylamine(DDA)and3-(dimethylamino)-1-propylamine(DMAPA)or
N-(3-aminopropyl)diethanolamine(APDEA)inTHFatroomtemperatureina1:1ratio(Scheme1b).
The prepared poly(glycidyl 3-dimethylaminopropylcarbamate-co-glycidyl dodecylcarbamate)
(P(GDMAPA -co-GDDA )) (3) and poly(glycidyl 3-aminopropyldiethanolcarbamate-co-glycidyl
15 12
dodecylcarbamate) (P(GAPDEA -co-GDDA )) (4) were purified by dialysis in methanol and
16 11
characterized by 1H NMR, 13C NMR spectroscopy, and SEC analysis (Figures S7–S12). In both
cases, the different functional groups are statistically distributed along the polyglycidol
backbone. However, the higher reactivity of DMAPA and APDEA in comparison to
DDA leads to a slightly uneven ratio of functionalities. P(GDMAPA -co-GDDA ) (3)
Polymers 2018, 10, 96 15 1210 of 18
and P(GAPDEA -co-GDDA ) (4) were further reacted with an excess of methyl iodide
16 11
iannd TPH(GFAPDaEtA16-rcooo-GmDDAt1e1)m (p4e) rwateurree futrotheqr uraetaecrtnediz ewitthh ean teerxtcieasrsy ofa mmientheyl mioodieidtiee sin (TSHchFe mate ro1ocm).
Ttehmepseyranttuhrees itzoe dqupatoelryn(igzley cthidey tler3t-iatrriym aemthiynlea mmionieotpierso p(Syclhcaemrbea m1ca)t. eT-choe- gslyynctihdeyslizdeodd peocylyl(cgalrybcaidmyal t3e-)
(tPri(mGeTtMhyAlPaAm15i-ncoop-GroDpDyAlc1a2r))ba(5m)aatned-cop-ogllyy(cgidlyycl idydlo3d-aemcyilncoarpbraompyaltde)i eth(aPn(oGlTmMAePtAh1y5-lccoa-rGbDaDmA1a2)t)e -co(-5g)l yciadnydl
dpooldye(cgylylccaidrbyal m3-aatme)in(Po(pGrAopPDyEldMiAet1h6a-cnoo-lGmDeDthAy11lc)a)r(b6a)mwaetree-cpou-grilfiyceiddybly ddoiadleycsyislcianrbmamethataen) o(lPa(nGdAPaDnEMaAly16z-ceod-
bGyDD1AH11)N) (M6) Rw,e1r3eC pNurMifiRe,da bnyd dSiEalCysaisn ainly msiest.hanol and analyzed by 1H NMR, 13C NMR, and SEC analysis.

SScchheemmee 11.. SSyynntthheettiicc ppaatthhwwaayy ttoo PP(G(GTTMMAAPPAA15-c-coo-G-GDDDAD1A2) ()5)( 5)anadn dPP(G(GAPADPEDMEAM16-Aco--GcoD-DGA1D1)D A(6).) ((6a)).
15 12 16 11
(Fau)nFcutinocntiaolinzaaltiizoanti oonf oPfGP27G (1)( 1w)iwthi tphhpehneynl yclhclholroorfoofromrmataet,e p,pyryirdidinien/eD/CDMCM, r,t,r t2,02 0hh; ;((bb)) RReeaaccttiioonn ooff
27
PP((GGPPCC))27 (2(2) )wwitihth DDDDAA aanndd DDMMAAPPAA//AAPPDDEEAA, ,TTHHFF, ,rrtt, ,4422 hh;; ((cc)) QQuuaatteerrnniizzaattiioonn ooff tteerrttiiaarryy aammiinneess wwiitthh
27
methyl iodide, THF, rt, 20 h.
methyliodide,THF,rt,20h.
11HH aanndd 1133CC NNMMRR ssppeeccttrraa ooff PP((GGTTMMAAPPAA15-co-c-oG-GDDDAD12A) (5)) (i5n) DinMDSMOS-dO6 -sdhoswho cwhacrhaacrtaecritsetriics tsiicgsniaglnsa olsf
the dodecyl and trimethylpropylammonium15 groups ad12jacent to the carb6amate moieties, proving the
ofthedodecylandtrimethylpropylammoniumgroupsadjacenttothecarbamatemoieties,provingthe
ssuucccceessssffuull ffuunnccttiioonnaalliizzaattiioonno offP PGG27 ((11)).. IInn tthhee 11HH NNMMRR ssppeeccttrruumm ((FFiigguurree 22aa)),, tthhee cchhaarraacctteerriissttiicc ssiiggnnaallss
of the dodecyl functionality appea2r7 as three multiplets at δ = 0.74–0.90 (Signal 20), δ = 1.30–1.44 (Signal
of the dodecyl functionality appear as three multiplets at δ = 0.74–0.90 (Signal 20), δ = 1.30–1.44
18), and δ = 2.85–2.99 ppm (Signal 17), and a singlet at δ = 1.20 ppm (Signal 19). The
(Signal 18), and δ = 2.85–2.99 ppm (Signal 17), and a singlet at δ = 1.20 ppm (Signal 19).
trimethylpropylammonium groups are shown as three multiplets δ = 1.72–1.91 (Signal 11), δ = 3.00–
The trimethylpropylammonium groups are shown as three multiplets δ = 1.72–1.91 (Signal 11),
3.17 (Signal 10/13), and δ = 3.26–3.43 ppm (Signal 12). A multiplet at δ = 3.82–4.19 ppm (Signal 9/16)
δ = 3.00–3.17 (Signal 10/13), and δ = 3.26–3.43 ppm (Signal 12). A multiplet at δ = 3.82–4.19 ppm
shows the methylene group of the glycidol repeating unit. In the 13C NMR spectrum (Figure S13), the
(Signal9/16)showsthemethylenegroupoftheglycidolrepeatingunit. Inthe13CNMRspectrum
distinctive signals of the dodecyl groups are found at δ = 13.8 (Signal 23), δ = 22.0–28.9 (Signal 22),
(FigureS13),thedistinctivesignalsofthedodecylgroupsarefoundatδ=13.8(Signal23),δ=22.0–28.9
and δ = 31.2 ppm (Signal 21). The representative signals of the trimethylpropylammonium
(Signal22),andδ=31.2ppm(Signal21). Therepresentativesignalsofthetrimethylpropylammonium
functionality are shown at δ = 26.2 (Signal 13), δ = 37.3 (Signal 12), δ = 52.2 (Signal 15), and δ =
functionalityareshownatδ=26.2(Signal13),δ=37.3(Signal12),δ=52.2(Signal15),andδ=63.2ppm
63.2 ppm (Signal 14). Further, the signal of the carbamate groups can be found at δ = 156.0 ppm
(Signal14). Further,thesignalofthecarbamategroupscanbefoundatδ=156.0ppm(Signal11/19).
(Signal 11/19).

Figure 2. 1H NMR spectra of P(GTMAPA15-co-GDDA12) (5) measured in DMSO-d6 (a) and P(GAPDEMA16-co-
GDDA11) (6) measured in MeOD (b).