Editorial

Renewable Resources for Polymer Chemistry: A Sustainable Alternative?

In ages of depleting fossil reserves and

an increasing emission of greenhouse

gases, it should be obvious that the

utilization of renewable feedstocks is

one necessary step towards a sustain-

able development of our future. In this

context, it is important to mention

that nature produces a vast amount of

biomass (�1011 tonsp.a.), ofwhichonly

some 3.5% are currently used by

mankind.[1] Thus, the development

ofnew industrial uses of this feedstock

can certainly contribute to a sustain-

able development and our research

efforts should be focused on this

sustainable alternative for the chemi-

cal industry. Additional feedstock

alternatives based on fossil resources,

such as coal, the more efficient exploi-

tation of oil fields, the use of oil sands,

and many others that are currently

discussed, will ultimately deplete.

Some sooner, some later. It goes with-

out saying that also these fossil alter-

natives come at a higher feedstock

price and much research efforts are

necessary to make these resources

accessible on industrial scale. So why

not change to the one and only true

sustainable alternative right now and

devote all of our research efforts to the

efficient and sustainable use of renew-

able raw materials? For myself, this

question has only one possible

answer! Nevertheless, in order to

achieve the goal of long term substitu-

tion of fossil resourceswith renewable

ones, we have tomake sure thatwe do

not exploit nature and still produce

enough foodand feed for an increasing

population. The latter might be diffi-

cult and will certainly result in com-

petition for agricultural land, which

might for instance be overcome by

afforestation of degraded areas in

order to increase the production of

lignocellulosic biomass.[2] Addition-

ally, more agricultural land and its

ever more efficient use will be neces-

sary. Thus, this feedstock change is not

only a challenge for chemists, but for

Macromol. Rapid Commun. 2011, 32, 1297–1298

� 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhe

our society as a whole. In my opinion,

we have to start facing this challenge

right now, since there is no true (long-

term) alternative.

As already mentioned above, the

development of new utilization and

application possibilities of renewable

resources can certainly secure the

necessary starting materials for

the chemical industry on a long term

basis and, probably equally important

and in combination with the princi-

ples of greenchemistry, contribute to a

rethinking of the way chemistry is

conceived in industry, academia and

the public. This rethinking process has

certainly begun and can, for instance,

be evidenced by the steadily increas-

ing number of conferences and pub-

lications that are concerned with the

efficient use of renewable starting

materials. Even if itmight take several

decades to more or less completely

shift our feedstock basis towardsmore

sustainable alternatives, already now,

mainly driven by public demand, a

large variety of newproducts based on

renewables emerge on the market.

Additionally, many examples exist in

the chemical industry already for a

long time that do not use fossil feed-

stocks. In Germany, for instance, the

use of renewable raw materials for

industrial applications has a long

tradition and is steadily increasing.

In 2008, Germany used a total of 3576

thousand tons of renewable raw

materials for industrial applications

(�15% of all chemical feedstocks),

whereofplantoils are themajor source

(�40%), followed by carbohydrates,

natural rubber, proteins, and others.[3]

The use of these resources is manifold

and includes polymers, soaps & deter-

gents, coatings & paints, lubricants,

and many more. In order to further

increase the share of renewables in the

industry and to be ready for times

when fossil resources are depleted or

too expensive to be further exploited, a

continuousdevelopmentofnewappli-

im wileyonlinelibrary.com

cation possibilities and more sustain-

able alternatives to the existing pro-

cedures are necessary. Within this

special issue ofMacromolecular Rapid

Communications, leading experts of

the field thus share their current

findings on possible uses of renewable

raw materials for polymer chemistry

applications.

This special issue starts with an

overview by Palkovits et al. on the

possible uses of cellulose, the most

abundantnaturalpolymer.Apart from

well-established and new possibilities

of cellulose dissolution and regenera-

tion, this feature provides an excellent

overview on the manifold building

blocks that can be derived from

cellulose. Many of the other contribu-

tions (a total of eight) deal with the

synthesis of plant oil derived mono-

mers and polymers. Interestingly,

many research teams focus on the

combination of the plant oil derived

fatty acids with carbohydrate based

raw materials in order to tune the

properties of the resulting polymers.

Heinze and coworkers thus report on a

new preparation method of starch

esters and show that their starch

palmitates are able to form transpar-

ent filmswith good adhesion. Gandini

and his team on the other hand

describe thepreparationofmonomers,

which are based on vegetable oil

derivatives bearing furan hetero-

cycles, and their polymerization via a

double click strategy consisting of

thiol-ene and Diels-Alder reactions.

Webster and Pan use epoxidized soy-

bean oil fatty acids in combination

with sucrose and other polylols to

obtain biobased epoxy resins exhibit-

inghighmodulus in combinationwith

hard and ductile thermosetting prop-

erties. Larock et al. on the other hand

describe waterborne castor oil based

chemically bonded polyurethane-

silica high performance nanocompo-

site coatings that were prepared via a

sol-gel process. Mathers and his team

DOI: 10.1002/marc.201100488 1297

1298

www.mrc-journal.de

Editorial

take a different and very original

approach to obtain plant oil derived

polymers by performing self-metath-

esis reactions of highly unsaturated

plant oils in order to obtain 1,4-

cyclohexadiene, which was then iso-

merized to 1,3-cyclohexadiene and

subsequently polymerized using a

Ni(II) catalyst.Biodegradable fattyacid

based polyanhydrides are reported by

Galia et al., who also used thiol-ene

click chemistry for their monomer

synthesis. Mecking and his team

extend their research on long-chain

fatty acid derived polyesters by self-

metathesis of undecenoic acid, reduc-

tion and hydrogenation of the

resulting C20-diacid to yield the

corresponding C20-diol and final poly-

condensation of these monomers to

obtain the fully renewable polyester

20,20. A different strategy to possible

polyethylene substitutes based on

plant oils is reported by Turunc and

Meier, who polymerized renewable

dienemonomers by thiol-ene addition

reactions and ADMET polymerization.

In addition to the fatty acid based

polymers, six contributions deal with

carbohydrate derived monomers and

polymers. The contributionsbyHeinze

et al. and Gandini et al. used fatty acid

based copolymers and were already

above. Dove and his team describe

chain-end functionalized poly(lac-

� 2

tide)s, which were prepared via orga-

nocatalytic methods and subse-

quently modified using the click

reaction between tetrazines and nor-

bornenes. The groups of Weder and

Supaphol on the other hand demon-

strated that cellulose nanowhiskers

can be electrospunwith poly(ethylene

oxide) into uniaxially-oriented arrays

ofmicrofibers. The teamofRehahnand

Klein used cellulose derived 5-hydro-

xymethylfurfural as a basis for the

synthesis of water-free polyurethane

foams by using nitrogen (resulting

from the Curtius rearrangement of a

new furan based carboxylic azide) as

the blowing agent. On the other hand,

an isocyanate-free route to biobased

segmented polyureas using organoca-

talysis is reported by the group of

Koning and Noordover. Last but not

least, Miller at al. took the challenge of

developing thermoplastic materials

that are derived from lignin by pre-

paring polyalkylene 4-hydroxybenzo-

ates,polyalkylenevanillates, andpoly-

alkylene syringateswithgood thermal

properties.

These contributions do not only

show the manifold possibilities when

working with renewable feedstocks,

but alsohighlight theneed for efficient

chemical transformations to achieve

the synthetic targets, as for instance

evidenced by the use of various click

Macromol. Rapid Commun. 2011, 32, 1297–1298

011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

type chemistries throughout this spe-

cial issue. Moreover, sustainability

issues, such as the avoidance of toxic

chemicals and the reduction of waste,

are on the agenda and might help to

change the public opinion of the

chemical industry. In summary, this

special issue thus provides a snapshot

of the current state-of-the-art in the

development of renewable and sus-

tainable alternatives for the chemical

industry.

Finally, I would like to take this

opportunity to sincerely thank all

contributors for their outstanding

contributions and encourage the poly-

mer community to join this exiting

field of research.

Michael A. R. Meier

Karlsruhe Institute of Technology

This article has been amended and

replaced on August 29, 2011 to correct

an error detected after publication.

[1] Source: PRO-BIP 2009 study by Shen,Haufe & Patel: http://www.chem.uu.nl/nws/www/publica/Publicaties%202009/PROBIP2009%20Final% 20June%202009.pdf.

[2] J. O. Metzger, A. Hutterman, Naturwis-senschaften 2009, 96, 279.

[3] Source: Fachagentur nachwachsendeRohstoffe e.V. (agency for renewableresources), www.fnr.de.

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