<PAGE>

                                                                    Exhibit 10.4


                           ENZON PHARMACEUTICALS, INC.

                        RESTRICTED STOCK AWARD AGREEMENT

                  THIS AGREEMENT, made as of January 5, 2005, by and between
ENZON PHARMACEUTICALS, INC., a Delaware corporation (the "Company"), and _______
("Executive").

                                   BACKGROUND

                  The Company wishes to grant a restricted stock award to
Executive in connection with the execution by Executive of his Employment
Agreement.

                                      TERMS

                  In consideration of the premises and mutual covenants herein
contained, the parties hereto hereby agree as follows:

                  1. Award

                  The Company, effective as of the date of this Agreement,
hereby grants to Executive a restricted stock award of ____________ shares (the
"Shares") of common stock of the Company (the "Common Stock") pursuant to the
Company's 2001 Incentive Stock Plan subject to the terms and conditions set
forth herein and to the terms of the Employment Agreement between the Company
and Executive, dated as of the date hereof (the "Employment Agreement"), which
are specifically referenced herein. Capitalized terms used but not defined
herein shall have the meanings ascribed to such terms in the Employment
Agreement.

                  2. Vesting

                  Subject to the terms and conditions of this Agreement, the
Executive's Shares shall vest according to the following schedule:

                     Date                Number of Shares that Vest on such Date
                     ----                ---------------------------------------



                  3. Restriction on Transfer

                  Until any group of Shares vests pursuant to Sections 2 or 4
hereof, none of such unvested Shares may be sold, assigned, transferred,
pledged, hypothecated or otherwise disposed of or encumbered, and no attempt to
transfer such unvested Shares, whether voluntary or involuntary, by operation of
law or otherwise, shall vest the transferee with any interest or right in or
with respect to such Shares.
<PAGE>

                  4. Early Vesting; Forfeiture

                  (a) All of the Shares shall be subject to immediate vesting in
accordance with Section 10(a)(viii) of the Employment Agreement.

                  (b) In the event the Company terminates Executive's employment
as the Company's _______________________________________________________________
_____________________ for Cause pursuant to Section 9(a)(iii) of the Employment
Agreement, Executive will forfeit all unvested Shares granted to Executive
pursuant to Section 1 hereof.

                  (c) In the event Executive's employment as the Company's
___________________________________________________________________________ is
terminated as a result of Executive's death, all unvested Shares granted to
Executive pursuant to Section 1 hereof shall vest immediately upon Executive's
death.

                  (d) Upon termination of Executive's employment as the
Company's ______________________________________________________________________
__________ on account of Executive's disability pursuant to Section 9(a)(ii) of
the Employment Agreement, all unvested Shares granted to Executive pursuant to
Section 1 hereof shall vest immediately upon such termination.

                  (e) In the event Executive voluntarily terminates his
employment as the Company's ____________________________________________________
________________________, other than for Good Reason pursuant to Section 9(c) of
the Employment Agreement, Executive will forfeit all unvested Shares granted to
Executive pursuant to Section 1 hereof.

                  (f) Notwithstanding anything to the contrary in this Agreement
or the Employment Agreement, the Compensation Committee of the Board of
Directors of the Company (the "Committee") or the Board of Directors of the
Company (the "Board"), in its sole discretion, may waive any of the forfeiture
requirements in this Section 4 or may accelerate the vesting of all or a portion
of the Shares as the Committee or the Board so determines.

                  (g) In accordance with Section 11 of the Executive's
Employment Agreement, in the event of a Change in Control (within the meaning of
the Employment Agreement), all unvested Shares granted to Executive under
Section 1 hereof shall become fully vested immediately prior to such Change in
Control.

                  5. Issuance and Custody of Certificate

                  (a) The Company shall cause to be issued one or more stock
certificates, registered in the name of Executive, evidencing the Shares. Each
such certificate shall bear the following legends:

                           "The shares of common stock represented by this
certificate are subject to forfeiture, and the transferability of this
certificate and the shares of stock represented hereby are subject to the
restrictions, terms and conditions (including restrictions against transfer)
contained in a Restricted Stock Award Agreement entered into between Enzon
Pharmaceuticals, Inc. (formerly known as Enzon, Inc.) and the registered owner
of such shares dated _______________. A Copy of the Restricted Stock Award
Agreement is on file in the office of Enzon Pharmaceuticals, Inc."

                                       2
<PAGE>

                  (b) Contemporaneous with the execution hereof, Executive shall
cause stock powers relating to the Shares executed by Executive to be delivered
to the Company.

                  (c) Each certificate issued pursuant to Section 5(a) hereof,
together with the stock powers relating to the Shares, shall be deposited by the
Company with the Secretary of the Company or a custodian designated by the
Secretary. The Secretary or such custodian shall issue a receipt to Executive
evidencing the certificate or certificates held which are registered in the name
of Executive.

                  (d) After any Shares subject to this Agreement vest pursuant
to Sections 2 or 4(b) hereof, the Company shall promptly cause a certificate or
certificates evidencing such vested Shares without the legal legend called for
in Section 5(a) (together with the stock powers relating to the Shares) to be
released and delivered to Executive or Executive's legal representatives,
beneficiaries or heirs.

                  (e) Prior to issuance of the Shares, the Company shall have
caused such issuance to be registered under the Securities Act of 1933, as
amended.

                  6. Distributions and Adjustments

                  (a) In the event of a merger, consolidation, reorganization,
recapitalization, stock dividend or other event, the number and character of the
Shares shall be adjusted at the same time and to the same extent as other shares
of Common Stock are adjusted as a result of any such event. If all or any
portion of the Shares vest in Executive subsequent to any such change in the
number or character of the shares of Common Stock, Executive shall then receive
upon such vesting the number and type of securities or other consideration which
Participant would have received if the Shares had vested prior to the event
changing the number or character of outstanding shares of Common Stock.

                  (b) Any additional shares of Common Stock, any other
securities of the Company and any other property (except for cash dividends)
distributed with respect to the Shares prior to the date the Shares vest shall
be subject to the same restrictions, terms and conditions as the Shares. Any
cash dividends payable with respect to the Shares shall be distributed to
Executive at the same time cash dividends are distributed to stockholders of the
Company generally.

                  (c) Any additional shares of Common Stock, any securities and
any other property (except for cash dividends) distributed with respect to the
Shares prior to the date such Shares vest shall be promptly deposited with the
Secretary or the custodian designated by the Secretary to be held in custody in
accordance with Section 5(c) hereof for Executive's benefit and shall be
distributed to Executive as provided in Section 6(b) when the Shares vest.

                                       3
<PAGE>

                  7. Taxes

                  (a) The issuance of the Shares to Executive pursuant to this
Agreement involves complex and substantial tax considerations, including,
without limitation, consideration of the advisability of Executive making an
election under Section 83(b) of the Internal Revenue Code. The Executive is
urged to consult his own tax advisor with respect to the transactions described
in this Agreement. The Company makes no warranties or representations whatsoever
to the Executive regarding the tax consequences of the grant to the Executive of
the Shares or this Agreement. Executive acknowledges that the making of any
Section 83(b) election shall be his personal responsibility.

                  (b) In order to provide the Company with the opportunity to
claim the benefit of any income tax deduction which may be available to it in
connection with this restricted stock award, and in order to comply with all
applicable federal or state tax laws or regulations, the Company may take such
action as it deems appropriate to insure that, if necessary, all applicable
federal or state income and social security taxes, which are the sole and
absolute responsibility of Executive, are withheld or collected from Executive.

                  (c) Executive may elect to satisfy his federal and state
income tax withholding obligations arising from the receipt of, or the lapse of
restrictions relating to, the Shares by (i) delivering cash, check (bank check,
certified check or personal check) or money order payable to the order of the
Company, (ii) having the Company withhold a portion of the Shares otherwise to
be delivered having a fair market value based on the last reported sale price of
a share of Common Stock on the Nasdaq Stock Market (or if the Shares no longer
trade on the Nasdaq Stock Market, the closing or last reported price on the
principal exchange or system on which they trade) (the "Fair Market Value")
equal to the amount of such taxes, or (iii) delivering to the Company Common
Stock having a Fair Market Value equal to the amount of such taxes. The Company
will not deliver any fractional Share but will pay, in lieu thereof, the Fair
Market Value of such fractional Share. The Participant's election must be made
on or before the date that the amount of tax to be withheld is determined.
Otherwise, the Company shall be entitled to withhold taxes due in such manner as
the Company determines in its discretion.

                  8. Miscellaneous

                  (a) Executive shall be entitled at all times to all of the
rights of a stockholder with respect to the Shares, including without limitation
the right to vote and tender such Shares and to receive dividends and other
distributions as provided in and subject to the provisions of Section 6.

                  (b) Executive hereby acknowledges receipt of a copy of the
Employment Agreement. The Employment Agreement is also available for inspection
during business hours at the principal office of the Company.

                  (c) This Agreement shall not confer on Executive any right
with respect to continuance of employment by the Company.

                                       4
<PAGE>

                  (d) This Agreement shall inure to the benefit of, and be
binding upon, the Company, its successors and assigns, and upon Executive, his
administrator, executor, personal representative, successors and heirs.

                  (e) Except as provided in Section 4(f), no change to or
modification of this Agreement shall be valid unless it is in writing and signed
by the Company and Executive. .

                  IN WITNESS WHEREOF, The parties hereto have caused this
Restricted Stock Award Agreement to be executed on the day and year first above
written.



                                                 ENZON PHARMACEUTICALS, INC.


                                                 By:_______________________




                                                 EXECUTIVE



                                                 ---------------------------


                                       5